HomeMy WebLinkAboutWRAB 2015-11-16 Complete PacketWATER RESOURCES ADVISORY BOARD MEETING
MEETING DATE: Monday, 16 November 2015
MEETING TIME: 7:00 p.m.
MEETING LOCATION: Municipal Services Center, 5050 E. Pearl St., Boulder, CO 80301
Agenda Highlights:
1. Call to Order (7:00 p.m.)
2. Approval of Sep. 21 Meeting Minutes (7:01 p.m.)
3. *Public Comment (7:05 p.m.)
4. Update on Bear Canyon Creek Mitigation Study (7:15 p.m.)
5. *Public Hearing and Consideration of a Recommendation to City Council Regarding the Boulder
Creek Restoration Master Plan (7:45 p.m.)
6. Sustainability Programs Update (8:15 p.m.)
7. Matters from Board (8:35 p.m.)
• Discussion of City Council 2016 Retreat Questions
8. Matters from Staff (8:50 p.m.)
• Update on Water Fluoridation
9. Discussion of Future Schedule (9:05 p.m.)
10. Adjournment (9:15)
* Public Comment Item
Agenda item times are approximate.
Information:
• Please contact the WRAB Secretary email group at:
WRABSecretary@bouldercolorado.gov
• Packets are available on-line at: http://www.bouldercolorado.gov – A to Z, Water
Resources Advisory Board (WRAB), Next Water Resources Advisory Board Meeting
WRAB Minutes
21 September 2015
Page No. 1
CITY OF BOULDER, COLORADO
BOARDS AND COMMISSIONS MEETING MINUTES
Name of Board / Commission: Water Resources Advisory Board
Date of Meeting: 21 September 2015
Contact Information of Person Preparing Minutes: Rene Lopez 303-413-7149
Board Members Present: Vicki Scharnhorst, Dan Johnson, Mark Squillace, Lesley Smith; Mike Barnes
Board Members Absent: None
Staff Present: Jeff Arthur, Director of Public Works for Utilities
Bret Linenfelser, Water Quality Environmental Services Manager
Russ Sands, Watershed Sustainability & Outreach Supervisor
Eric Ameigh, Public Works Projects Coordinator
Joe Taddeucci, Water Resources Manager
Kim Hutton, Water Resource Specialist
Ken Baird, Utilities Financial Manager
Rene Lopez, Board Secretary
Consultants Present:
Lee Rozaklis, Rozaklis & Associates
Meeting Type: Regular
Agenda Item 1 – Call to Order [7:03 p.m.]
Agenda Item 2 – Approval of the 17 August 2015 Meeting Minutes [7:04 p.m.]
Motion to approve minutes from 17 August 2015 as presented.
Moved by: Squillace Seconded by: Smith
Vote: 4:0; Barnes ineligible for vote
Agenda Item 3 –Swearing in of the new WRAB Member / Election of Officers [7:07 p.m.]
Oath of office administered to new board member Mike Barnes
Election of Board Officers:
Chair: Scharnhorst nominated by Johnson, Seconded by: Squillace
Vote: 5:0
Vice Chair: Johnson nominated by: Squillace Seconded by: Scharnhorst
Vote: 5:0
Secretary: Squillace nominated by Johnson, Seconded by: Smith
Vote: 5:0
Agenda Item 4 – Public Participation and Comment [7:10 p.m.]
Public Comment: None
Agenda Item 6 – Matters from Board: [7:10 p.m.]
• Johnson
Flood control project plans updates over the next year
Agenda Item 7 - Matters from Staff: [7:18 p.m.]
Russ Sands
- Water Conservation Update (7:21 p.m.)
Outdoor vs indoor water usage discussions
Discussions concerning the 5 budget options and staff time
Discussions regarding water usage during non-drought years
Comments regarding usage by CI customers
Eric Ameigh
- Rate Study Update (8:18 p.m.)
WRAB update tentatively scheduled for November
Kim Hutton, Joe Taddeucci and Lee Rozaklis
- Water Supply Model Update (8:26 p.m.)
Comments on allocating water based on senior water rights on the Boulder Creek
basin and farther downstream for crop irrigation uses.
Clarification on the ability to model for increasing storage capacity, projected uses,
WRAB Minutes
21 September 2015
Page No. 2
supply and demand and climate change variability.
Questions regarding reevaluation of the drought ordinance in the city.
Clarifications regarding the reliability criteria and the year severity measures in
recent drought years
Joe Taddeucci
- Water Resources Update (9:02 p.m.)
Colorado Water Plan (CWP)
Carter Lake Pipeline
• Questions regarding Right-of-way acquisition budget for pipeline
• Boulder feeder canal future discussions
• Comments regarding changes to water rates with the new pipeline
Water Supply Update
Jeff Arthur
- Other Matters from Staff (9:38 p.m.)
Civic Area and flood information
Agenda Item 8 – Future Schedule [9:43 p.m.]
Upcoming meetings will consist of information items such as the following:
- November schedule is full, October is empty, and so changes may be coming to the
schedule.
- Retreat for possibly October or November.
Adjournment [9:46 p.m.]
There being no further business to come before the Board at this time, by motion regularly adopted, the
meeting was adjourned at 9:46 p.m.
Motion to adjourn by: Smith Seconded by: Squillace
Motion Passes 5:0
Date, Time, and Location of Next Meeting:
The next WRAB meeting will be Monday, 19 October 2015 at 7:00 p.m., at the City's Municipal
Services Center, 5050 East Pearl St., Boulder, CO 80301
APPROVED BY: ATTESTED BY:
_______________________________ __________________________________
Board Chair Board Secretary
_____________________________ ___________________________________
Date Date
An audio recording of the full meeting for which these minutes are a summary, is available on the Water
Resources Advisory Board web page.
https://bouldercolorado.gov/boards-commissions/water-resources-advisory-board-next-meeting-agenda-and-packet
AGENDA ITEM #________PAGE________
C I T Y O F B O U L D E R
WATER RESOURCES ADVISORY BOARD
AGENDA ITEM
MEETING DATE: November 16, 2015
AGENDA TITLE: Information Item - Update on the Bear Canyon Creek Flood
Mitigation Plan
PRESENTERS:
Jeff Arthur, Director of Public Works for Utilities
Annie Noble, Acting Principal Engineer for Flood and Greenways
Ward Bauscher, Engineering Project Manager
Christin Shepherd, Flood and Greenways Engineer
EXECUTIVE SUMMARY:
The purpose of this memorandum is to provide an update to the WRAB on the progress
and current status of the Bear Canyon Creek Flood Mitigation Plan. An information item
memo was submitted to the WRAB in April 2015 for this mitigation plan and is attached
for reference as Attachment A. The projected timeline for the mitigation plan, as
outlined in the previous memo, has been extended due to modeling challenges, including
the comparison to and the incorporation of a two-dimensional model, and an increase in
study area due to spill flow paths identified in the modeling.
There is currently no adopted flood mitigation master plan for Bear Canyon Creek.
Although improvements have been made along the creek over time, the 2013 flood
showed that areas along the creek lack conveyance capacity during large storm events.
As a result, the city retained AMEC Foster Wheeler (AMEC) in December 2014 to help
identify mitigation needs and evaluate potential alternatives to alleviate future flooding
along Bear Canyon Creek in the selected stream reaches. The study reaches are
identified in Figure 1 below.
AMEC’s original scope of work included the analysis of three segments of the creek
using the original one-dimensional HEC-RAS models. Development in the floodplain
often triggers updates to the floodplain mapping through a letter of Map Revision
(LOMR) processed through FEMA. AMEC modified the HEC-RAS model to
incorporate revisions that occurred since the last mapping study into what is considered a
“Best Information” model. The revisions made the model unstable and highlighted other
modeling gaps. The older HEC-RAS technology is ineffective in modeling spill flows
that leave the main channel. It was determined that the use of an updated two-
dimensional mapping technology (Flow-2D) might help staff and AMEC better
understand the spill flow paths throughout the drainage way. The HEC-RAS and Flow-
AGENDA ITEM #________PAGE________
2D models would be compared and a determination of the degree and location of further
model refinement would be examined.
As a result, the city expanded AMEC’s scope of work to develop a more comprehensive
model using Flow-2D to better define major flow paths and spill flows. As warranted,
the Flow-2D model would be overlaid and converted to a 1-dimensional HEC-RAS
model that is more appropriate for analysis of system hydraulics and corresponding flood
mitigation measures.
To date, AMEC has established a survey of the baseline conditions along the drainage
way, refined the working HEC-RAS model including incorporating Letter of Map
Revisions (LOMRs) from several improvement projects, and identified potential
mitigation alternatives. AMEC is currently modeling Bear Canyon Creek using Flow-2D
and will compare it to the working model to determine where further model refinement is
necessary. Once the model is sufficiently refined, alternatives will continue to be
analyzed for incorporation in the Bear Canyon Creek Flood Mitigation Plan. The
mitigation plan will be presented to WRAB for recommendation when complete.
AGENDA ITEM #________PAGE________
Figure 1:
BOARD AND COMMISSION FEEDBACK
An information item providing a status update of the Bear Canyon Creek Mitigation Plan
was submitted to WRAB in April, 2015. Staff has not yet received any board or
commission feedback.
AGENDA ITEM #________PAGE________
PUBLIC FEEDBACK
An Open House was held on July 1, 2014 to listen to concerns and introduce the
upcoming mitigation plan, with approximately 45 people attending. After bringing
AMEC on board, another open house was held on April 27, 2015 to present possible
mitigation alternatives. Approximately 30 people attended this meeting. A third open
house was held on August 20, 2015 to present preliminary mitigation alternates and
receive feedback from property owners in the vicinity. Approximately 75 people
attended this meeting. Notifications for these meetings were made by the following
methods:
Postcards were mailed to all property owners in the study area;
Posters were placed at various visible locations along the creek;
Emails were sent to all interested parties whom have signed up for email
notifications and to all parents of children attending Bear Creek Elementary
School; and
A project web site has been developed to provide information
(https://bouldercolorado.gov/flood/bear-canyon-creek-flood-mitigation-project).
Forty-seven comments have been received via the website comment tool to date.
Generally, the public has not only supported possible mitigation alternatives, but has
actively sought implementation of alternatives throughout the three reaches.
BACKGROUND
Bear Canyon Creek originates in City of Boulder Open Space and has a drainage area of
5.3 square miles and is 6.3 miles long. Much of the Bear Canyon Creek basin within city
limits was developed for residential use during the late 1950’s and early 1960’s. Flood
events have occurred along the creek in May 1969, May 1995, August 2007 and in
September 2013.
Since initial development, this major drainage way has undergone numerous
improvements and benefits from good maintenance within the improved reaches.
However, the flooding of September 2013 brought to light some key issues which
contributed to property damage and safety concerns. In general, problems stemmed from
poor conveyance capabilities, debris blockage at major crossings and lack of effective
flow return zones.
In 2014, the city hired AMEC Foster Wheeler (AMEC) to assist in developing a flood
mitigation plan for Bear Canyon Creek. The study focuses on three distinct areas for
mitigation alternatives as outlined in the attached memo dated April 2015. The areas
were chosen based on problem areas identified during the 2013 flooding event. The
study area consists of two stream segments which are broken into three reaches:
1. City Limits to Lehigh St.
2. Lehigh St. to Broadway
3. Moorhead Ave. to Baseline Rd.
AGENDA ITEM #________PAGE________
ANALYSIS
Flood mitigation master plans rely on sound hydraulic modeling to identify and evaluate
flood mitigation measures. Over the years several Letter of Map Revisions (LOMRs)
using separate hydraulic models have been developed along the creek to reflect
development changes. These revisions needed to be incorporated into a working model.
AMEC’s original scope of work included the analysis of three segments of the creek
using only the original models. While refining the model and comparing it to actual
inundation areas from 2013, AMEC and city staff noted gaps in information as well as
the need for further refinement in areas where spill flows occur. It was determined that
further model refinement was necessary and that the new modeling effort should use the
city’s current approach that uses a two-dimensional model (Flow-2D) to define major
flow paths and spill flows. Flow-2D utilizes the latest technology to measure and
incorporates real-world topography that makes it ideal for identifying flow paths that split
away from the main channel. Once the flow paths and flood depths are identified, the
two-dimensional model would be converted back to a HEC-RAS one dimensional model
more commonly used for infrastructure analysis. This one-dimensional HEC-RAS model
would then be used for analysis of system hydraulics and corresponding flood mitigation
measures.
AMEC is currently developing the two-dimensional model.
NEXT STEPS:
Staff and the consultant team will continue to prepare a draft mitigation plan using the
new hydraulic information to better analyze the alternatives. Next steps include:
Development and examination of feasible mitigation alternatives. This process will
use updated information from the refined two-dimensional and one-dimensional
hydraulic models.
Identification of recommended alternative scenarios. The most effective alternatives
will be grouped into several plan alternatives and then evaluated in the updated
model.
Creation of planning level benefit-cost ratios. In this step, the most effective
alternatives will be evaluated using a benefit cost analysis (BCA) to help identify
feasibility and ranking of alternatives.
Refinement of the mitigation plan including a staff recommendation.
The mitigation plan will then be presented to the WRAB for consideration. We
anticipate this presentation to occur in the second quarter of 2016. If approved by
WRAB, the plan will then be presented to City Council for consideration.
Once adopted by the WRAB and Council, recommended alternatives in the Bear
Canyon Creek Mitigation Plan will be programmed as capital improvements for
construction as funding is available.
ATTACHMENTS
Attachment A: Bear Canyon Creek Mitigation Information Item Memo – April 15th,
2015
Bear Canyon Creek Informational Memo 1
INFORMATION PACKET
MEMORANDUM
To: Water Resources Advisory Board
From: Jeff Arthur, Director of Public Works for Utilities
Annie Noble, Acting Principal for Flood and Greenways
Ward Bauscher, Engineering Project Manager
Kristin Dean, Utilities Planner
Christin Shepherd, Flood and Greenways Engineer
Date: April 27, 2015
Subject: Information Item: Bear Canyon Creek Flood Mitigation Plan
EXECUTIVE SUMMARY:
Bear Canyon Creek currently has no adopted master flood mitigation plan. Although
much of the drainage has been significantly improved to convey 100-year flood flows,
the 2013 flood event raised performance concerns about areas in the drainage way. The
Flood Management and Greenways group, as part of a comprehensive mitigation study,
initiated the Bear Canyon Creek Mitigation Plan in 2014. The purpose of this
memorandum is to update WRAB on the mitigation plan progress and describe the
overall study approach. This study focuses on three distinct areas based on performance
concerns during the 2013 flooding event:
Reach 1: City Limits to Lehigh Street
Reach 2: Lehigh Street to Broadway
Reach 3: Moorhead Avenue to Baseline Road
Bear Canyon Creek Informational Memo 2
The city retained AMEC Foster Wheeler (AMEC) in December 2014 to help identify
mitigation needs and evaluate potential alternatives to alleviate future flooding along
Bear Canyon Creek in the selected stream reaches.
Bear Canyon Creek Informational Memo 3
The study will be comprised of 3 phases with distinct goals.
Phase 1: consists of creating baseline hydraulic and loss models to help identify
problem areas and inform mitigation alternative choices for consideration.
Mitigation alternatives will be broadly identified. Phase 1 summary memos from
the consultant are attached and summarized within.
Phase 2: utilizes the baseline models created in Phase1. Alternatives will be
analyzed and incorporated into the models to determine their benefit. A Cost-
Benefit analysis will be performed to help rank the feasibility of alternatives.
(Information item and presentation to WRAB scheduled for August 2015)
Phase 3: refines the alternative measures. The recommended alternatives will be
compiled as a recommended Flood Mitigation Plan. This plan will be presented
to WRAB with a request for a recommendation to City Council. (Action item
November 2015)
The Phase 1 (Draft) Flood Mitigation Master Plan for Bear Canyon Creek Conceptual
Alternative Development memo (“Analysis”) is included as Attachment A. This is
AMEC’s analysis describing existing conditions and considerations for the preliminary
alternative recommendations. Additionally, AMEC has provided a memo describing
their baseline model for the study area. This memo entitled Phase 1: Flood Loss
Estimation Technical Memorandum is attached as Attachment B.
BOARD AND COMMISSION FEEDBACK
The Bear Canyon Creek Mitigation Plan is in the preliminary phase and has had no board
or commission feedback.
PUBLIC FEEDBACK
An Open House was held on July 1, 2014 to introduce this mitigation plan.
Approximately 45 people attended this meeting, where the initial study parameters and
extents were discussed. Additionally, another open house is scheduled for April 27th,
2015 directly prior to the WRAB meeting. Poster boards will be presented for
discussion, outlining the study reaches and potential mitigation options.
Public notification post cards about this WRAB meeting and the preceding Open House
were sent to all property owners in the study area and a project web site has been
developed to provide information and receive comments, with 24 comments received via
the website comment tool to date ( https://bouldercolorado.gov/flood/bear-canyon-creek-
flood-mitigation-project). Additionally, posters notifying the neighborhood of the meeting
and open house were posted at various visible locations along the creek. Emails have
been sent to all interested parties who have signed up for email notifications and to all
parents of children attending Bear Creek Elementary School.
BACKGROUND
Bear Canyon Creek Informational Memo 4
Bear Canyon Creek originates in City of Boulder Open Space and has a drainage area of
5.3 square miles. The creek is 6.3 miles long. Much of the Bear Canyon Creek basin
within the Boulder City limits was developed for residential use during the late 1950’s
and early 1960s. Channel infrastructure along Bear Canyon Creek has been
overwhelmed during flood events on May 7th 1969, May 1995, August 15th 2007 and
September 2013, among others.
Since the initial development, this major drainage way has undergone numerous
improvements and benefits from a formal maintenance plan, however the flooding of
September 2013 brought to light some key issues which contributed to property damage
and safety concerns. In general, problems stemmed from poor conveyance capabilities,
debris blockage at major crossings and lack of effective flow return zones.
Much of the Bear Canyon Creek ecosystem consists of non-native species that do not do
well during extreme flood events in the foothills. These species create large amounts of
debris as compared to more native species and this debris can be transported downstream
creating blockages to flow.
Although the channel is relatively stable during normal flows, unstable channel
conditions contribute to the generation and transport of sediment during extreme events.
In the upper reaches of Bear Canyon Creek, a steeper channel gradient encourages
sediment transport. The sediment typically deposits at culverts or shallower sections,
reducing their capacity. During the 2013 flood, sediment deposition blocked many of
the culverts completely and caused flows through surrounding neighborhoods and streets.
This study focuses on 3 distinct areas better described below.
Reach 1
The reach is defined from the City Limits to Lehigh Street and consists of City Open
Space, medium density suburban, and high density townhome use. Major constrictions
occur at Wildwood Road, a pedestrian bridge connecting Bear Creek Elementary school
to Bear Mountain Drive, and an old boiler tank (as a culvert) crossing the stream at
Wildwood and Ithaca. Although the regulatory floodplain is narrow in this area, Reach 1
had significant flooding and property damage during the September 2013 flood. Much of
the damage was caused by flows created as the channel dammed with debris. Locations
with potential for debris mitigation, floodplain storage and stream stabilization
requirements will be identified.
Reach 2
Reach 2 is divided into two sections, Reach 2A and Reach 2B. Reach 2A extends from
the crossing at Lehigh to the crossing at Broadway, while reach 2B extends from
Broadway to Moorhead Avenue. Although the mitigation study will only examine
alternatives in Reach 2A, Reach 2B is included because it will benefit from the upstream
mitigation measures and should be included in the benefit cost analysis.
Reach 2A is an urban transportation zone, with the floodplain mainly confined to Table
Mesa Drive and the creek situated within the parkway. The stream channel is designed to
Bear Canyon Creek Informational Memo 5
contain the 25-year event with drop structures and crossings sized for stability and
conveyance, while the Parkway itself forms the floodplain. Residential structures would
be minimally impacted by flooding, however, commercial properties at the downstream
limits of the reach are susceptible to damage in larger events. The Harvard lane culvert
in particular has insufficient capacity to pass flood flows, especially with debris blockage,
which causes spill flows downstream in Reach 2B, where substantial damage results.
Reach 2B passes through Martin Park and a small residential area until it reaches
Moorhead. This area has 100-year flood mitigation improvements that were constructed
in the 1980s and 1990s, but saw damages during the 2013 flood event from spill flows at
the Harvard Lane culvert. It became clear that this area (Martin Acres), which was
previously excluded from the scope, needed to be included as improvements in reach 2A
could benefit this area.
Reach 3
Reach 3 is also separated into a study reach, Reach 3A and an impacted reach, Reach 3B.
Reach 3B sees diverted flows originating from Reach 3A. Reach 3A begins at US
Highway 36 and extends through the University of Colorado Williams Village Campus to
Baseline Road. This reach is currently undeveloped except for the lower limits, and
consists of disturbed land and low flow crossings. The channel has insufficient capacity
for any flows above the 2 year event, and is overgrown with invasive species. Poor outlet
conditions at the US Highway 36 culvert exacerbate flooding upstream and create a spill
situation across highway 36 in extreme events. The private drive of St. Andrews
Presbyterian Church at the downstream limits of the reach just upstream of Baseline Rd.,
contributes to spills across Baseline Rd, severely limiting the effectiveness of the Bear
Canyon Creek culvert under Baseline Rd. This church location demarks the northern end
of the study area for this mitigation plan.
Reach 3B begins at Baseline Road and continues to Mohawk Drive. It was included for
cost benefit analysis only.
The remainder of the drainage has had significant improvements up to the confluence of
Bear Canyon Creek and Boulder Creek which occurs just to the north of Arapahoe Rd.
and east of Foothills Parkway.
Bear Canyon Creek Informational Memo 6
ANALYSIS
Typically, flood mitigation plans are developed with the intent to adequately convey a
100-year storm event. Designing major drainage way systems to transport the 100-year
event is a policy standard included in the Boulder Valley Comprehensive Plan, the
Comprehensive Flood and Stormwater Utility Master Plan and the UDFCD Drainage
Criteria Manual and is applicable to new development in the city.
Due to the existing residential development and previous channel mitigation in several
reaches of the creek, this mitigation planning effort covers only 3 specific sections of the
drainage, Reaches 1, 2, and 3 which were described in detail in the Background section of
this memo. To understand the full implications of mitigation alternatives, three steps
were taken to provide the analysis for Bear Canyon Creek Mitigation Plan - Phase 1:
1. A baseline conditions model was created,
2. The potential property damage during a 100-year storm event in the baseline
conditions model were analyzed, and
3. Mitigation improvements were identified based on this baseline model and
observations from the 2013 flood event. These mitigation alternatives will be
modeled and analyzed in Phase 2 of the study.
Bear Canyon Creek Informational Memo 7
Development of the Baseline Conditions Model – Best Available Information Model
In order to accurately analyze flows and potential improvements in the area of Bear
Canyon Creek, a complete hydraulic model needed to be created. In April of 1985, a
Flood Insurance Study (FIS) was conducted that produced detailed hydrologic and
hydraulic information for the City of Boulder and its vicinity. In May of 1987,
Greenhorne & O’Mara, Inc developed a final Hydrologic Analysis Report that developed
and delineated flood hazard areas for Bear Canyon Creek. These reports did not result in
a complete hydraulic model for the entire stretch of Bear Creek (from City Limits to its
confluence with Boulder Creek).
Segments of Bear Canyon Creek had been analyzed and smaller hydraulic models
developed for each area but they did not seamlessly connect as one cohesive model. In
order to fully analyze the potential mitigation efforts along this major drainage way, a
complete HEC-RAS model of the entire stream was needed. The City and the Urban
Drainage and Flood Control District (UDFCD) transferred all available modeling data to
AMEC who developed a Best Available Information model to produce the 10-year flood
(10% annual chance), 50-year flood (2% annual chance), 100-year flood (1% annual
chance), and 500-year flood (0.2% annual chance) events under existing conditions as a
baseline model. UDFCD has informed the city that, when no complete model exists, a
Best Available Information model is acceptable to use for planning and mitigation
purposes.
Potential Damages Incurred During 100-year Flood Event in Baseline Model
Hazus-MH, FEMA’s GIS-based natural hazard property damage estimation tool, was
initially used to perform a flood loss estimation within the three study reaches. Site-
specific building information for each of the study areas was provided by the FEMA
Region VIII via the City. This data required some coordination to accurately represent
on the ground scenarios. The second input into the model was a depth grid, which is a
grid-based GIS file that indicates the depth of flooding at a particular grid cell. Flood
depth grid data provided by FEMA was limited to the effective 100 year (1% annual
chance) return period. The building data was formatted and imported into the Hazus
regions for loss analysis using the 100-year FEMA depth grid.
The building point layer was overlaid onto each depth grid in GIS and a spatial join was
performed to determine the depth of flooding at each structure for each return period.
The tabular database was incorporated into the modified Benefit Cost Analysis (BCA)
spreadsheet to perform the property damage loss calculations. Per FEMA guidance, loss
curves from the Army Corps of Engineers were used during this analysis.
Each reach has been modeled for the 2-, 10-, 50-, 100- and 500-year event. Reaches 2
and 3 have risk to losses during the 100 and all reaches have losses during a 500-year
event but only reach 3 has risk during the 50 year event.
Reach 1 has the lowest risk to flooding of the 3 reaches and does not result in flood loss
from the 100-year event. The 500-year event affects 35 residential structures, with a total
damage of $1.1M. While there is no modeled risk during the more frequent interval
Bear Canyon Creek Informational Memo 8
floods, it should be noted that debris and culvert blockage during the 2013 flood
(estimated to be a 25 year event) caused flooding in the 500-year floodplain in this reach.
Reaches 2A and 2B have the most buildings of the three reaches, including the most
commercial structures. The commercial structures are associated with the Table Mesa
Shopping Center at the intersection of Table Mesa and Broadway. Reaches 2A and 2B
have the greatest risk from the 100 and 500-year floods. The majority of this damage is
associated with reach 2B east of Broadway. The 100-year flood analysis results in less
than $400k in damages between Lehigh and Broadway in reach 2A, and $1.1M
associated with the 500 year event. When losses in the 2B reach are included, estimated
losses are closer to $5.5M and $8.5M for the 100 and 500-year events respectively.
Reaches 3A and 3B have 213 residential structures, and several religious institutions at
risk to flooding. This reach is the only reach to have some risk to the more frequent 50-
year flood event (8 structures total). Reach 3A has substantial risk to the 500-year flood
event.
Total estimated damages across all study reaches for the theoretical 50 year flood event is
estimated at $335,000; the 100- year and 500-year total estimated damages are $6.9M
and $18.7M respectively.
Proposed Improvements and Their Affect on Potential Losses
The purpose of this analysis was to explore mitigation strategies aimed at reducing
damage from flood events and to create a ‘planning level’ benefit cost analysis to assist
with mitigation alternatives analysis in Phase 2 of the study
These alternatives fall into three categories: non-structural measures, structural
improvements, and debris management.
Non-structural alternatives: These will target vegetation management and
maintenance. The riparian zone will be evaluated for vegetative debris
production, transport and control.
Structural alternatives: These will consist of stream restoration strategies,
floodplain creation or modification and capacity improvements to stream
crossings. The feasibility of debris control structure solutions will be evaluated as
well as improvements to pedestrian crossings.
Debris management: Sediment and debris catchment areas will be evaluated for
storage potential, location relative to downstream crossings and maintenance
access.
Reach 1
Vegetation management and debris control are crucial to improving the capacity of the
channel. Invasive species should be controlled and the channel stabilized to reduce
channel degradation. Several opportunities exist for debris mitigation, including areas
immediately upstream of Wildwood and Lehigh. Another opportunity exists for a larger
area immediately adjacent to the Bear Creek Elementary School within the Bear Creek
Bear Canyon Creek Informational Memo 9
Park. These areas could be graded to receive debris deflected into them with strategically
placed rock structures in the stream, and maintenance access provided to remove the
accumulated debris periodically.
The area immediately adjacent to Wildwood above Ithaca is currently degraded and full
of invasive species, both willow and elm trees. This area could be re-graded to connect
the floodplain and be stabilized with non-structural treatments such as root wads and
faschines (bundles of straw staked with native willow and seeded with a riparian seed
mix). The area could then be replanted and managed as a riparian corridor per the
Greenways Master Plan.
The Wildwood culvert should be assessed for improvements to hydraulics and debris
control. These improvements may consist of maintenance near the up and downstream
face of the structure for sediment and vegetation, modifications to the structure including
beveling of the top section, placing fins or a debris deflector in front of the entrance or
increasing the cell size or number. The pedestrian bridge (shown in the attached map as
CR-R1-2) was replaced after the 2013 flood, however, the channel approaches up and
downstream are severely incised and should be stabilized. The old boiler section culvert
will be recommended for removal, and the sharp bend below assessed for stability. A
map outlining planning level potential mitigation alternatives is included below.
Bear Canyon Creek Informational Memo 10
Reach 2
While much of this channel functioned well during the 2013 flood event, there are
mitigation alternatives that could improve key functions of the reach. Minimizing street
flooding in this reach could benefit the access and egress in the nearby neighborhoods.
An alternative exploring an enlarged channel capable of conveying up to the 100-year
event without impacting the travel lanes of Table Mesa Drive could be beneficial. This
enlarged channel section could include a multi-use path within the channel. Culverts
downstream of Broadway have already been improved in this manner, and the crossing at
Lehigh would benefit greatly from enlarging the structure to accommodate both foot
traffic and flood flows. As part of a federal grant application for the Transportation
Improvement Program (TIP), a preliminary feasibility analysis and conceptual level
design for an underpass across Table Mesa at the Harvard Lane intersection was
explored.
Reach 2B extends from Broadway to Moorhead Avenue. This reach performed well
during the 2013 flood, with the exception of damage caused by spill flows from
upstream.
Bear Canyon Creek Informational Memo 11
Reach 3
Since reach 2B is included for property loss purposes only, a small section has been
included in the mitigation study for Reach 3A. The area immediately downstream of
Moorhead Avenue is inundated by flows during a 100-year storm, some contributed by
Skunk Creek from the north upstream of US Highway 36, as well as the culvert from the
highway itself. Much of the storm water accumulation in this area may be solved by
altering the outlet conditions for the Highway 36 culvert. This culvert could be improved
by re-grading the area immediately downstream and reconfiguring the pedestrian path as
it connects to the pedestrian bridge to the north of Highway 36. Currently, the separation
wall for the path effectively limits flows in the culvert to only one of the two cells. It
may also be necessary to install a third cell at this crossing to insure passage of higher
flows given debris blockage and pedestrian path considerations.
Downstream of the pedestrian bridge, the floodplain opens up to the Williams Village
Campus of the University of Colorado (CU). CU has a master plan for this area that
includes residential/institutional use (family student housing) and incorporates a stream
crossing for access. Vegetation management and grading to create floodplains are two
possible strategies that could be beneficial in this reach.
Finally, the private drive for the church located immediately upstream of Baseline Road
severely limits the capacity of the Baseline culvert. This undersized culvert at the church
diverts flows on to Baseline Road instead of allowing them to flow through the Baseline
culvert. During the 2013 event, this split flow caused damage at and around the church
as well as into reach 3B.
Reach 3B begins at Baseline and extends downstream to Mohawk Drive. The
channel in Reach 3B functions relatively well with some exceptions. Damages in
this area are mainly influenced by spills upstream of the reach, and thus no
mitigation measures are planned for this reach as a part of this study.
Bear Canyon Creek Informational Memo 12
COST BENEFIT ANALYSIS
During Phase 2 of the study, a cost benefit analysis will be conducted after a full list of
alternatives is developed.
NEXT STEPS:
Following public input from the April Open House and WRAB meeting, staff and the
consultants will continue to prepare a draft Mitigation Plan. Phase 2 of the plan will
consist of a feasibility analysis of mitigation alternatives. AMEC and city personnel will
develop these alternatives into a complete plan for comparison and public comment.
Potential environmental impacts, as well as legal and Right of Way issues will be
identified for further analysis by city staff. Phase 2 of the mitigation study is scheduled
to be presented to WRAB at the August 2015 meeting. Phase 3 of the study will include
a set of alternatives which will be presented to WRAB in November 2015 with a request
for a recommendation to approve the mitigation plan. If approved, the plan will be
presented to City Council for consideration.
ATTACHMENTS
Attachment A: Conceptual Alternative Development memo
Attachment B: Phase 1: Flood Loss Estimation Technical Memorandum
Attachment C: Open House Figures (5)
Attachment D: Master Plan Guidance and Policies
Phase 1: Flood Mitigation Master Plan for Bear Canyon Creek
Conceptual Alternative Development
Background
The current conditions along Bear Canyon Creek do not represent a natural ecosystem.
Currently, many non-native species are present that negatively contribute to the functioning of
the system. Species diversity is low, consisting of primarily non-native crack willow (Salix
fragilis), Russian olive (Elaeagnus angustifolia), and Siberian elm (Ulmus pumila). Crack willow
specifically is highly susceptible to breaking branches during extreme weather events, and likely
contributed to the clogging of culverts and subsequent overland flooding. In urbanized
neighborhoods, constrained channels undermine the root systems of species such as Siberian
Elm, resulting in large woody debris transported downstream during an extreme event.
In addition, unstable channel conditions contribute to the generation and transport of sediment.
In the upper reaches of Bear Canyon Creek, channel slope in excess of 5 to 7 percent create
excessive potential energy which results in high velocities and channel shear stress. The
stream transitions from its headwaters as a cascading gully in the sandstone of the Fountain
Formation which make up the Flatirons to an alluvial floodplain across the Pierre shale to the
east, passing through the uplifted sandstone layers of the Dakota sandstone making up the first
hogback west of boulder. The changes in gradient result in an imbalance of energy which
seeks equilibrium through picking up and transporting sediment. This high energy gradient
passes through the softer alluvium formed by natural erosive forces forming meanders until the
stream meets a constriction, either from the hard underlying sandstone or by an
anthropomorphic feature such as a bridge or culvert. As flows pass through a constriction, the
head loss is translated upstream as a slowing in velocity and the sediment load is deposited,
while the cleaner water then accelerates through the constriction.
In an extreme event, such as the 2013 flood, deposition at these constrictions actually block the
channel and flows overtop whatever feature has formed the constraint. In the case of a culvert
or bridge, these overtopping flows then find their way back to the natural stream valley via
roadways and neighborhoods, picking up more debris from damaged structures and creating
more deposition zones where smaller constrictions develop. Typically, the culverts and bridges
are designed for a 10-25 year event considering debris blockage. In the 2013 event,
characterized as a 25-50 year peak flow over the Bear Canyon Creek watershed, the actual
precipitation distribution was on the order of a one thousand year event. This resulted in
saturated soils and friable (easily transported) debris in the floodplain which created a slurry
flow as the peak runoff occurred. Culverts and bridges were completely blocked by debris, and
the resultant overtopping condition resembled a 100 year flooding event. This resemblance
however, is only in the pathways seen by the floodwaters. An actual 100 year event would
produce greater depth along these pathways, creating far more damage to structures and
utilities.
Bear Canyon Creek Informational Item 1
Attachment A: Conceptual Alternative Development Memo
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Conceptual Alternative Development
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 2
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
The purpose of this study is to explore mitigation strategies aimed at reducing damage from
flood events. The creek in general has been described as being relatively stable during
baseflow conditions and smaller events, requiring only routine maintenance. Conceptual level
alternatives have been developed here which address the problems associated with larger
events, but must also take into account the underlying morphology and ecology of the stream.
These alternatives fall into three categories: non-structural measures, structural improvements,
and debris management. Non-structural alternatives will target vegetation management and
maintenance. The riparian zone will be evaluated for vegetative debris production, transport
and control, while the maintenance program will be assessed and suggestions made for
improvements. Structural alternatives consist of stream restoration, floodplain connection and
capacity improvements to stream crossings. The feasibility of debris control structure solutions
will be evaluated as well as improvements to pedestrian crossings. Finally, debris catchment
areas will be evaluated for storage potential, location relative to downstream crossings and
maintenance access. They will also be evaluated as either public or ecosystem amenities
depending on ownership and designated use.
Reach 1
Reach 1 extends from the upstream limit of the study area at the corporate limits to just
upstream of Lehigh Street. The reach consists of City open space, medium density suburban,
and high density townhome use. Major constrictions occur at Wildwood Road, a pedestrian
bridge connecting Bear Creek Elementary school to Bear Mountain Drive, and an old boiler tank
crossing the stream at Wildwood and Ithaca. The stream itself transitions from a high
gradient,cascading gully section upstream of Wildwood to a V-shape section below Wildwood
which becomes deeply incised downstream of Ithaca.
Vegetation management and debris control are crucial to improving the capacity of the channel.
Invasive species should be controlled and the channel stabilized to reduce channel degradation.
Several opportunities exist for debris mitigation, including areas immediately upstream of
Wildwood and Lehigh. Another opportunity exists for a larger area immediately adjacent to the
Bear Creek Elementary school within the Bear Creek park. These areas could be graded to
receive debris deflected into them with strategically placed rock structures in the stream, and
maintenance access provided to remove the accumulated debris periodically.
The area immediately adjacent to Wildwood above Ithaca is currently degraded and full of
invasive species, both willow and elm trees. This area could be regraded to connect the
floodplain and stabilized with non-structural treatments such as root wads and faschines
(bundles of straw staked with native willow and seeded with a riparian see mix). The area could
then be replanted and managed as a riparian corridor per the greenways master plan.
The Wildwood culvert should be assessed for improvements to hydraulics and debris control.
These improvements may consist of maintenance near the up and downstream face of the
structure for sediment and vegetation, modifications to the structure including beveling of the top
section, placing fins or a debris deflector in front of the entrance or increasing the cell size or
number. The pedestrian bridge (CR-R1-2) was replaced after the 2013 flood, however the
channel approaches up and downstream are severely incised and should be stabilized. The old
boiler section will probably need to be removed, and the sharp bend below assessed for
stability.
Reach 2
Bear Canyon Creek Informational Item 2
Attachment A: Conceptual Alternative Development Memo
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Conceptual Alternative Development
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 3
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
Reach 2 is divided into two sections. Reach 2A extends from the crossing at Lehigh to
Broadway, while reach 2B extends from Broadway to Moorhead. The upstream limits of these
reaches are technically at the upstream face of these crossings so that the downstream
mitigation impacts can be assessed.
Reach 2A is an urban transportation zone, with the floodplain mainly confined to Table Mesa
Drive and the creek situated within the parkway. The stream channel is designed to contain the
25 year event with drop structures and crossings sized for stability and conveyance, while the
Parkway itself forms the floodplain. Residential structures are minimally impacted by the
flooding source, however commercial properties at the downstream limits of the reach are
susceptible to damage in larger events. The Harvard lane culvert in particular has insufficient
capacity to pass flood flows, especially with debris blockage, and overland flows are translated
to Reach 2B, where substantial damage results.
Debris management is limited in this area to the catchment immediately upstream of Lehigh
described earlier, and a small catchment upstream of Yale Road. The catchment at Yale
receives flows from a significant tributary area, and could be important in mitigating debris
downstream.
A great opportunity exists to combine an enlarged channel through this reach capable of
conveying up to the 100 year event with a pedestrian path system. Culverts downstream of this
area have already been improved to this degree, and the crossing at Lehigh would benefit
greatly from enlarging the structure to accommodate both foot traffic and flood flows. This could
be combined with a structural channel section downstream to Harvard with at grade crossings in
between to minimize cost. The crossing at Harvard Lane and Broadway has already undergone
a preliminary feasibility analysis and conceptual level design, but must include a more
comprehensive consideration of the hydraulics involved.
Reach 2B extends from Broadway to Moorhead Street. This reach performed well during the
2013 flood, with the exception of damage caused by spill flows from upstream. The area
immediately downstream of Moorhead is inundated by flows contributed by Skunk Creek from
the north upstream of US Highway 36, as well as the culvert from the highway itself. For this
reason, the areas of flooding immediately upstream and extending downstream are included in
Reach 3. No opportunities for flood mitigation as part of this plan are identified in Reach 3B.
Reach 3
Reach 3 is also divided into two sections for the same reasons identified in Reach 2. Reach 3A
begins at US Highway 36 and extends through the University of Colorado South Campus to
Baseline Road. This reach is currently undeveloped except for the lower limits, and consists of
disturbed land and low flow crossings. The channel has insufficient capacity for any flows
above the 2 year event, and is overgrown with invasive species. Poor outlet conditions at the
US Highway 36 culvert exacerbate flooding upstream and create a spill situation across
highway 36 in extreme events. A private drive at the downstream limits of the reach just
upstream of Baseline contribute to spills across Baseline, severely limiting the effectiveness of
the Bear Canyon Creek culvert under Baseline Road.
The outlet conditions for the Highway 36 culvert could be greatly enhanced by regarding the
area immediately downstream and reworking the pedestrian path. Currently, the separation wall
for the path effectively limits flows in the culvert to only one of the two cells. By extending the
path approach farther to the east, perhaps incorporating this into improvements with the
Bear Canyon Creek Informational Item 3
Attachment A: Conceptual Alternative Development Memo
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Conceptual Alternative Development
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 4
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
pedestrian bridge immediately downstream, the hydraulic efficiency of the Highway 36 crossing
may be enough to pass extreme events. It may also be necessary to install a third cell at this
crossing to insure passage of higher flows given debris blockage and pedestrian path
considerations.
Downstream of the pedestrian bridge, the floodplain opens up to the South Boulder Campus of
the University of Colorado. A master plan has been developed for this area that includes
residential/institutional use (student housing) and incorporates a stream crossing for access.
Vegetation management could enhance the conveyance capabilities in this area and reduce
floodplain width. It is anticipated however, that this measure will not provide sufficient gains to
eliminate flooding which impacts downstream areas adjacent to Baseline Road. A strategy
which incorporates a complete restructuring of the riparian corridor through this reach including
grading to reconnect the floodplain (FC-R3-1), stabilization of the stream, and a careful design
of any crossings could provide benefits to both the property owner (CU) and residential and
commercial interests downstream.
Finally, the private drive located immediately upstream of Baseline Road severely limits the
capacity of the Baseline culvert. This drive consists of two 36” squashed culverts which barely
have sufficient capacity to convey the channel discharges during spring runoff events. This
drive may benefit from a much larger culvert, a combination culvert low water crossing, or by
abandoning the crossing altogether. This crossing would require investigation in conjunction
with both improvements upstream aimed at confining the floodplain, and consideration of
containing resultant flows to downstream reaches.
Reach 3B begins at Baseline and extends downstream to Mohawk Drive. This area is greatly
influenced by the dynamics of flooding upstream. Spills which occur above baseline are
transmitted overland through residential neighborhoods to the confluence area immediately
upstream of Foothills Highway. This is a complicated confluence zone influenced by both South
Boulder Creek to the south and east, and Skunk Creek to the west. The channel itself in Reach
3B functions relatively well except for a sharp bend to the right immediately upstream of
Mohawk. Damages in this area are mainly influenced by spills upstream of the reach, and thus
no mitigation measures are planned for this reach as a part of this study. The capacity and
stability of the channel will, however be assessed as part of containing flows from upstream.
Bear Canyon Creek Informational Item 4
Attachment A: Conceptual Alternative Development Memo
Memo
March 30, 2015
To: Ward Bauscher, Engineering Project Manager, City of Boulder Public Works - Utilities
From: Jeff Brislawn, Hazard Mitigation Lead/Associate
CC: Joel McGuire, Project Manager
Ref: Flood Mitigation Master Plan Bear Canyon Creek
Re: Phase 1: Flood Loss Estimation Technical Memorandum
This report summarizes a study that estimated the building damage impacts from flooding on existing
development in three stream reaches along Bear Creek in the City of Boulder, Colorado. The results and
additional details on the methods follow in this technical memorandum.
Modeled Flood Losses
Background
Hazus-MH, FEMA’s GIS-based natural hazard loss estimation tool, was initially used to perform a flood
loss estimation within the reaches. Site-specific building information for each of the study areas was
provided by the FEMA Region VIII via the City. Inspection of the databased revealed that the building
dataset was missing point locations for several buildings within the 100 or 500 year floodplain. At least
452 points were missing, including one of the Bear Canyon townhomes that was flooded in 2013. Amec
Foster Wheeler staff identified the missing parcels and City staff was able to assist with developing point
data for these parcels and populate 8 columns of attributes to match up to the FEMA point data. We
also developed additional points so that individual condos/townhomes and business were represented
in the model. Many of these were represented by one point for large commercial parcels such as the
Table Mesa Shopping Center. Additionally, the provided attribute data needed additional processing
steps to prepare it for import into Hazus, including adding content value, estimated first floor height
based on building type, and latitude longitude.
The second input into the model was a depth grid, which is a grid-based GIS file that indicates the depth
of flooding at a particular grid cell. Flood depth grid data provided by FEMA was limited to the effective
100 year (1% annual chance) return period. The building data was formatted and imported into the
Hazus regions for loss analysis using the 100 year FEMA depth grid. Default reports to display Hazus
results do not work well with user-defined data, so the loss data needed to be aggregated outside of
Hazus in a spreadsheet. QC of the results revealed that the depth damage curves were not being
applied appropriately by Hazus and thus the loss estimation was underestimated. This is a known bug in
Hazus. In order to fix this we had to use a spreadsheet developed for a previous project as a work
around to ensure that the appropriate depth damage curve was being applied.
Attachment B
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Flood Loss Estimation Technical Memorandum
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 2
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
On February 25 the City provided an email that suggested the FEMA Benefit Cost Analysis (BCA)
methodology should be used instead of Hazus for a more comprehensive and accurate loss analysis.
The BCA module also uses Army Corp of Engineers (Corp) - developed depth damage curves as opposed
to the National Flood Insurance Program – Flood Insurance Administration curves in Hazus. The Corp
curves are considered more appropriate and are also used by UDFCD in master planning studies.
Subsequent conversations with the City suggested we should use the Corp curves and consider doing a
‘planning level’ benefit cost analysis to assist with alternative selection.
Further analysis of the 2013 flood event damage data and flood extent (including GIS and YouTube video
information) revealed that losses outside of the 100 year flood plain occurred in the Martin Acres reach
between Broadway and US 36. These losses were due to split flows near the Table Mesa – Broadway
intersection that diverted flows down streets and into the neighborhood and flooded homes in the 500
year floodplain. From this analysis it became clear that the area between Broadway and US 36 (Martin
Acres) that was previously excluded from the scope needed to be included, as improvements in reach 2
could benefit this area. A similar conclusion was reached for the area downstream of reach 3 north of
Baseline Rd. Additional building data was collected in these areas for analysis.
The following figure displays the study area and the limits of the 3 reaches and sub-reaches analyzed.
Loss Estimation Methodology
The methodology utilized shifted from Hazus-based to an initial planning-level BC analysis. A
spreadsheet provided by FEMA was used to aggregate building loss information. This was developed by
FEMA for input of detailed structure information into the FEMA BCA tool for drainage projects. Amec
Attachment B
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Flood Loss Estimation Technical Memorandum
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 3
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
Foster Wheeler used this spreadsheet tool moving forward. The spreadsheet was modified to include
depth damage curves for commercial properties as these properties are present in the study area.
This method utilizes estimated first floor heights based on the following building relationships from the
Hazus technical manual.
Source: Hazus Riverine Flood Technical Manual
The majority of the structures in the watershed are Pre-FIRM (constructed prior to the adoption of the
first Flood Insurance Rate Map on July 17, 1978) residential structures with a mix of slab and basements.
A grant-level BC analysis would require additional analysis, possibly including surveyed first floor
elevations or analysis of LiDAR data to refine the estimate of these. A grant-level BCA may also require
gathering additional benefit information to produce a benefit cost ratio of 1 or greater.
A best available information model was developed to produce the 10-year flood (10% annual chance),
50-year flood (2% annual chance), 100-year flood (1% annual chance), and 500-year flood (0.2% annual
chance) events. Due to the complex nature of the flooding source, certain assumptions had to be made
in the modeling process. Overtopping occurs at several major crossings, most notably Broadway Street
and Baseline Road. Spills from these areas become hydraulically disconnected from the main channel,
flow overland through streets and neighborhoods and then rejoin the floodplain downstream.
Boundaries for these flows were manually delineated in the original FHAD study, and digitized as part of
the current DFIRM. For the purposes of this analysis, areas outside of the main AE zone, yet within the
500-year floodplain were assumed to have a flooding depth of 2 feet for the 500-Yr analysis, 1 foot for
the 100-Yr analysis, and zero for the 50-Yr analysis. These areas were joined to the calculated depth grid
for areas within the main AE Zone for each corresponding recurrence interval.
The building point layer was overlaid onto each depth grid in GIS and a spatial join was performed to
determine the depth of flooding at each structure for each return period. The tabular database was
incorporated into the modified BCA spreadsheet to perform the loss calculations. Depth damage
functions in the BCA spreadsheet were applied to create a detailed loss estimate for buildings in the
reaches for the various flood events. The following figure is a snapshot from reach 3B that illustrates
Attachment B
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Flood Loss Estimation Technical Memorandum
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 4
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
the depth grid and flooded structures and how depth values were used in the spreadsheet to calculate
building damage, based on depth-damage curves within the spreadsheet tabs.
Results
Results of the analyses are presented in the following table, which is followed by a discussion of the
results by reach.
Attachment B
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Flood Loss Estimation Technical Memorandum
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 5
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
Table 1 Estimated Flood Loss by Stream Reach
The table displays losses by stream reach and sub-reach for the 50, 100, and 500 year flood events.
There was no risk of structure flooding to the 10 year event risk within any reach, thus no losses are
shown. All reaches have risk to the 100 and 500 year events. Only reach 3 has risk to the 50 year event.
Total damages across all reaches for the 50 year event is estimated at $335,000; the 100 year and 500
year total estimated damages are $6.9M and $18.7M respectively.
Reach 1 has the lowest risk to flooding of the 3 reaches and does not result in flood loss from the 100
year event. The 500-year event affects 35 residential structures, with a total damage of $1.1M. While
there is no modeled risk to the more frequent interval floods, it should be noted that debris and culvert
blockage during the 2013 flood (estimated to be a 25 year event) caused flooding in the 500 year
floodplain in this reach.
Reach 2A and 2B has the most buildings of the three reaches, including the most commercial structures.
The commercial structures are associated with the Table Mesa Shopping Center at the intersection of
Table Mesa and Broadway. This area has the greatest risk from the 100 and 500 year floods. The
Return Period Structures
Damaged
Building
Damage
Contents
Damage Total Damages Displacement
Days
500-year Flood 35 816,208$ 330,054$ 1,146,262$ 0 Days
100-Year Flood -$ -$ -$ 0 Days
50-Year Flood -$ -$ -$ 0 Days
500-year Flood 20 722,622$ 386,778$ 1,109,400$ 315 Days
100-Year Flood 11 252,533$ 67,119$ 319,652$ 0 Days
50-Year Flood -$ -$ -$ 0 Days
500-year Flood 143 5,738,407$ 1,717,123$ 7,455,529$ 7560 Days
100-Year Flood 117 4,006,369$ 1,139,296$ 5,145,664$ 4455 Days
50-Year Flood -$ -$ -$ 0 Days
500-year Flood 144 4,918,883$ 1,781,786$ 6,700,668$ 2070 Days
100-Year Flood 43 991,125$ 302,847$ 1,293,972$ 90 Days
50-Year Flood 7 249,852$ 79,161$ 329,013$ 180 Days
500-year Flood 70 1,700,570$ 624,577$ 2,325,147$ 540 Days
100-Year Flood 5 93,737$ 32,540$ 126,276$ 0 Days
50-Year Flood 1 3,913$ 1,878$ 5,791$ 0 Days
500-year Flood 412 13,896,690$ 4,840,317$ 18,737,006$ 10485 Days
100-Year Flood 176 5,343,763$ 1,541,801$ 6,885,564$ 4545 Days
50-Year Flood 8 253,765$ 81,039$ 334,804$ 180 Days
Total Damages for Study Area by Return Period
Reach 1; US Study Limit to Lehigh
Reach 2A; Lehigh to Broadway
Reach 2B; Broadway to Moorhead
Reach 3A; Moorhead to Baseline
Reach 3B; Baseline to DS Study Limit
Attachment B
Flood Mitigation Master Plan for Bear Canyon Creek
Phase 1: Flood Loss Estimation Technical Memorandum
Amec Foster Wheeler Environment & Infrastructure, Inc. P a g e | 6
1002 Walnut Street
Boulder, CO 80302
Tel (303) 443-7839
www.amecfw.com
majority of this damage is associated with reach 2B east of Broadway. The 100 year flood analysis
results in less than $400k in damages between Lehigh and Broadway in reach 2A, and $1.1M associated
with the 500 year event.
Reach 3A and 3B has 213 residential structures and a church at risk to flooding. This reach is the only
reach to have some risk to the more frequent 50 year flood event (8 structures total). Reach 3A has
substantial risk to the 500 year flood event.
Income Related Losses and Debris Generation Estimates
Hazus has utility in estimating Income related losses and debris (building related as opposed to soil and
woody debris), and these losses were calculated based on the Census block based inventory associated
with a Level 1 Hazus flood run, but utilizing the user-defined depth grids. These losses were modeled to
capture additional losses due to business interruption and debris estimates. Income related losses
include a one-time flood disruption cost, rental income losses, and capital income losses. A single Hazus
study area was created to encompass all three reaches. Total income losses were estimated at
$130,000 for the 100 year and $146,000 for the 500 year event. Debris generation was estimated at
1,150 tons for the 100 year and 1,303 tons for the 500 year event. These values, in addition to the
structure loss estimates previously discussed, can be used as a baseline for comparison as flood
mitigation alternatives are modeled in future phases of the project.
Attachment B
WildwoodRoadnearIthacaFloodplainConnectionFCͲR1Ͳ1Maintenance/Improvements:ͲremoveinvasivespeciesͲselectivelyregradeareatoprovidestorageͲreconnectfloodplaintoimprovechannelstabilityͲrevegetatewithdiverse,nativespeciesͲrestoreriparianecosystemWildwoodRoadnearIthacaChannelStabilizationCSͲR1Ͳ1Improvements:ͲrestorestablechannelgradientͲprovidecapacityforfloodeventsͲrestoreaquaticecosystemBear Canyon Creek Mitigation Study - Reach 1 Rendering CompilationOpen House Figure AAttachment C
BearCreekParkDebrisManagementDMͲR1Ͳ1,ChannelStabilizationCSͲR1Ͳ1ͲrestorestablechannelgradientͲprovidecapacityforfloodeventsͲselectivelyregradeareatoprovidestorageͲreconnectfloodplaintoimprovechannelstabilityͲrevegetatewithdiverse,nativespeciesͲrestoreriparianecosystemUpstreamofLehighDebrisManagementDMͲR1Ͳ3Improvements:ͲgradeareatoreceivedebrisͲprovideaccessformaintenanceͲstabilizechannelBear Canyon Creek Mitigation Study - Reach 1 Rendering CompilationOpen House Figure BAttachment C
WildwoodRoadCulvertCSͲR1Ͳ1Maintenance:ͲclearblockedcellͲrestorechannelUSandDSImprovements:ͲinstallfinsupstreamͲinstalldebrisdeflectorͲincreasecellsizeWildwood/BearCanyonDebrisManagementAreaDMͲR1Ͳ1,SpillControlSCͲR1Ͳ1:MaintenanceͲclearsedimentdebrisfromchannelͲmaintainvegetationupstreamImprovements:ͲgradeareatoreceivedebrisͲplacebermtoprovidespillcontrolͲprovideaccessformaintenanceͲstabilizechannelSCͲR1Ͳ2InstallbermtoprotectBearCanyonTownhomesBear Canyon Creek Mitigation Study - Reach 1 Rendering CompilationOpen House Figure CAttachment C
TableMesaDrive:CSͲR2Ͳ1Ͳ6,CRͲR2Ͳ2Ͳ6Improvements:ͲbreakͲawayrailingͲincreasecellsizeͲimproveinlethydraulicsͲwiden/stabilizechannelͲconstructpedestrianpathBear Canyon Creek Mitigation Study - Reach 2 Rendering CompilationOpen House Figure DAttachment C
CUSouthCampus:FloodplainConnectionFCͲR3Ͳ1MaintenanceͲclearsedimentdebrisfromchannelͲremoveinvasivevegetationImprovements:Ͳgradetoprovidefloodplainconnection/storageͲstabilizechannelͲprovideaccessformaintenanceͲplacebermtoprovidespillcontrolͲremove/upgradecrossingsBear Canyon Creek Mitigation Study - Reach 3 Rendering CompilationOpen House Figure EAttachment C
Master Plan Guidance and Policies Page 1
Master Plan Guidance and Policies
The Boulder Valley Comprehensive Plan (BVCP), the Comprehensive Flood and Stormwater
Utility Master Plan (“CFS”), the Greenways Master Plan and the Urban Drainage and Flood
Control District (UDFCD) Drainage Criteria Manual all contain policies related to floodplain
preservation, development, and mitigation. These documents guide the flood mitigation master
planning.
The following applicable policies are included in the BVCP:
3.19 Preservation of Floodplains
Undeveloped floodplains will be preserved or restored where possible through public land
acquisition of high hazard properties, private land dedication and multiple program coordination.
Comprehensive planning and management of floodplain lands will promote the preservation of
natural and beneficial functions of floodplains whenever possible.
3.20 Flood Management
The city and county will protect the public and property from the impacts of flooding in a timely
and cost-effective manner while balancing community interests with public safety needs. The
city and county will manage the potential for floods by implementing the following guiding
principles: a) Preserve floodplains b) Be prepared for floods c) Help people protect themselves
from flood hazards d) Prevent unwise uses and adverse impacts in the floodplain e) Seek to
accommodate floods, not control them. The city seeks to manage flood recovery by protecting
critical facilities in the 500-year floodplain and implementing multi hazard mitigation and flood
response and recovery plans.
3.21 Non-Structural Approach
The city and county will seek to preserve the natural and beneficial functions of floodplains by
emphasizing and balancing the use of non-structural measures with structural mitigation. Where
drainageway improvements are proposed, a non-structural approach should be applied wherever
possible to preserve the natural values of local waterways while balancing private property
interests and associated cost to the city.
3.22 Protection of High Hazard Areas
The city will prevent redevelopment of significantly flood-damaged properties in high hazard
areas. The city will prepare a plan for property acquisition and other forms of mitigation for
flood-damaged and undeveloped land in high hazard flood areas. Undeveloped high hazard flood
areas will be retained in their natural state whenever possible. Compatible uses of riparian
corridors, such as natural ecosystems, wildlife habitat and wetlands will be encouraged wherever
appropriate. Trails or other open recreational facilities may be feasible in certain areas.
3.23 Larger Flooding Events
The city recognizes that floods larger than the 100-year event will occur resulting in greater risks
and flood damage that will affect even improvements constructed with standard flood protection
measures. The city will seek to better understand the impact of larger flood events and consider
Attachment D
Master Plan Guidance and Policies Page 2
necessary floodplain management strategies including the protection of critical facilities.
The CFS contains the following guiding principles for flood management:
1. Preserve Floodplains (Preservation);
2. Be Prepared for Floods (Preparedness);
3. Help People Protect Themselves from Flood Hazards (Education);
4. Prevent Adverse Impacts and Unwise Uses in the Floodplain (Regulation);
5. Seek to Accommodate Floods, Not Control Them (Mitigation).
More detail about each of these guiding principles can be found in Chapter 3 of the CFS. The
fifth principal, as listed above, is directly related to mitigation and, in the CFS, more completely
states:
Seek to accommodate floods, not control them through planned and monitored system
maintenance, nonstructural flood proofing, opening non-containment corridors, overbank
land shaping to train flood waters, and limited structural measures at constrained
locations. Possible tools for implementation include:
o Update mitigation master plans to emphasize nonstructural measures.
o Re-evaluate mitigation priorities to eliminate bottlenecks, acquire land to avoid
channel improvements, provide non-structural overbank grading, target limited
flood protection improvements for high hazards, and research alternative
mitigation approaches.
o Assess any need for structural improvements with evaluation of multiple
alternatives.
o Focus on mitigating high hazard locations citywide and give priority to areas of
the greatest risk.
The UDFCD Drainage Criteria Manual contains the following basic policies:
The major drainageway system shall be capable of conveying water without flooding
buildings and shall remain relatively stable during a 100-year flood.
Public safety is fundamental to the major drainageway system.
Public acceptance of the major drainageway system depends on a multitude of factors
such as public perception of flood protection, channel aesthetics, right-of-way, open
space preservation, and channel maintenance.
Identify areas with potential for recreational use.
Consider environmental impacts and benefits and examine the advantages and
disadvantages.
Open channels are more desirable than underground conduits in urban areas because they
are closer in character to natural drainageways and offer multiple use benefits.
Consider two-stage channels. In some cases, it may be desirable to balance the 100-year
flow between a formal channel and the adjacent floodplain.
The purpose of the Greenways Program is to extend the stewardship of the city to important
riparian areas along the tributaries of Boulder Creek. The Greenways Master Plan includes the
following objectives:
Attachment D
Master Plan Guidance and Policies Page 3
To protect and restore riparian, floodplain, and wetland habitat;
To enhance water quality;
To facilitate storm drainage and mitigate floods;
To provide alternative transportation routes or trails for pedestrians and bicyclists;
To provide recreation alternatives;
To protect cultural resources.
The intent of the flood mitigation plan is to mitigate flood damage and facilitate storm drainage.
Improvements along this creek corridor could also include enhancements to water quality and
riparian areas.
These various master plan guiding principles and policies, specifically those related to
mitigation, have provided the foundation for developing the Bear Canyon Creek Mitigation Plan.
The initial alternatives under consideration include structural improvements, debris management
alternatives by improving the quality of the stream ecosystem and sediment control through
various measures including improving and connecting floodplain configurations.
Attachment D
AGENDA ITEM #________PAGE________
C I T Y OF B O U L D E R
WATER RESOURCES ADVISORY BOARD
AGENDA ITEM
MEETING DATE: NOVEMBER 16, 2015
AGENDA TITLE: Public Hearing and consideration of a recommendation to City
Council regarding the Boulder Creek Restoration Master Plan
PRESENTER/S:
Jeff Arthur, Director of Public Works for Utilities
Annie Noble, Acting Principal Engineer for Flood and Greenways
Katie Knapp, Engineering Project Manager
EXECUTIVE SUMMARY
The purpose of this memorandum is to present the Draft Boulder Creek Restoration
Master Plan for the WRAB’s consideration, input and recommendation to Council. The
Executive Summary of the plan is included as Attachment A and the full plan is
available at http://www.iconeng.com/project/boulder-creek/.
The City of Boulder joined regional partners, including the Urban Drainage & Flood
Control District (UDFCD), Boulder County, and the City of Longmont on the
development of the Boulder Creek Restoration Master Plan. This study was also partially
funded through the Colorado Water Conservation Board (CWCB) grant program. The
purpose of the master plan is to develop guidance in planning ongoing and long-term
watershed recovery efforts.
This project encompasses nearly 24-miles along Boulder Creek, extending from the
confluence with Fourmile Creek, located within Boulder Canyon upstream of the City of
Boulder, downstream to the confluence with the St. Vrain River, in the City of
Longmont, as shown in the Project Overview Map (Attachment B). The master plan
area crosses through the City of Boulder and also includes city-owned open space lands
outside of the city limits.
The focus of this master plan is to provide a planning tool for stream and ecological
restoration along Boulder Creek. As such, this master plan does not comprehensively
evaluate Boulder Creek through the City limits given that Boulder Creek through this
reach resembles more of an urban stream corridor. Instead, the plan addresses specific
areas of concern identified by the city staff and other interested parties who participated
in the planning processes. Similarly, the plan does not reevaluate the current 100-year
floodplain limits regulated by FEMA, although it is likely that the implementation of
some proposed projects would improve flood conveyance and the regulatory floodplain
limits.
Icon Engineering was retained by the project team to develop and evaluate alternatives
for Boulder Creek and prepare the draft master plan, which identifies and prioritizes
AGENDA ITEM #________PAGE________
feasible drainage, flood management, and restoration opportunities. Icon Engineering is
requesting input on the draft master plan prior to finalization. City staff is recommending
that the Civic Area Flood Information (Attachment C) be incorporated into the master
plan.
The draft master plan is now being presented to the WRAB for consideration, input and a
recommendation to City Council. After consideration and input from the WRAB and the
Open Space Board of Trustees (OSBT), the master plan will be finalized and presented to
City Council for acceptance.
STAFF RECOMMENDATION:
The development of the Civic Area Plan has included establishing guiding principles
around the life and safety concerns due to the flood risks. This information was compiled
into the Civic Area Flood Information (Attachment C) and includes flood regulatory
considerations, flood policy considerations and site opportunities and flood constraints.
It is recommended that these items be included in the final Boulder Creek Restoration
Master Plan.
Staff requests Water Resources Advisory Board consideration of this matter and action in
the form of the following motion:
Motion to recommend Council acceptance of the Boulder Creek Restoration Master
Plan with the inclusion of the Civic Area Flood Information.
BOARD AND COMMISSION FEEDBACK
Information on the Boulder Creek Restoration Master Plan was provided to the WRAB
on May 18, 2015 and the OSBT on October 15, 2015. The WRAB and OSBT did not
express any concerns about the master plan.
PUBLIC FEEDBACK
There have been many opportunities for public involvement and feedback throughout this
master planning process. Public meetings were held on March 10, 2015, March 18, 2015
and Sept. 29, 2015. Most attendees were property owners from Boulder County east of
the city limits with specific questions about their properties.
Public notification post cards about the public meetings were sent to property owners in
the study area, emails were sent to all interested parties whom have signed up for email
notifications and a project website was developed to provide information:
(http://www.iconeng.com/project/boulder-creek/). The project website also provided
opportunities for comments to be submitted electronically. All public comments received
were compiled and are included in Appendix B of the draft Boulder Creek Restoration
Master Plan.
BACKGROUND
The Boulder Creek watershed is approximately 440 square miles. It extends west of the
City of Boulder to the Continental Divide with elevations exceeding 13,000 feet.
AGENDA ITEM #________PAGE________
Boulder Creek generally flows east, and then northeast across the city. Boulder Creek is
tributary to 14 other major drainageways.
Boulder Creek has experienced several major flooding events, with the earliest reports
dating back to the 1840’s. The flood of record is reported to have occurred in 1894,
where nearly 3 days of rainfall washed out bridges and resulted in major damages to
homes and businesses. In 2013, between Sept. 9th and Sept. 15th, a large rainfall event
resulted in widespread flooding along the Colorado Front Range. Boulder Creek
experienced peak flows ranging from approximately 5,000 cubic feet per second (cfs) in
downtown Boulder, to over 9,000 cfs downstream of US Highway 287, equating to a 25-
to 50-year flood event. Although emergency flood repairs were completed, portions of
Boulder Creek were left in a state of disrepair, highlighting the need for a restoration
master plan.
Planning for floods within the City of Boulder and Boulder County dates back to the
early 1900’s. In 1910, Fredrick Law Olmsted, Jr. recommended against allowing
development to encroach upon the creek channel. Since then, Boulder Creek has been
the focus of numerous flood studies and master plans.
The City of Boulder completed a floodplain mapping study update for Boulder Creek
from the area west of 61st Street, upstream to the mouth of Boulder Canyon, west of
Boulder city limits. The study area encompassed a reach length of five and a half miles.
The new floodplain mapping was adopted by City Council on Sept. 18, 2012 and is
currently regulatory. FEMA began reviewing the mapping on Oct. 30, 2012. In
November 2013, FEMA indicated acceptance of the study results and initiated the
adoption of the new mapping through the Physical Map Revision process, a multi-year
process expected to be completed in December of 2016. Floodplain mapping provides
the basis for flood management by identifying the areas subject to the greatest risk of
flooding. Flood mitigation master planning is typically scheduled to follow floodplain
mapping updates.
There are many master planning documents with policies and guidance related to
floodplain management, preservation, development and mitigation, including:
• Boulder Valley Comprehensive Plan (BVCP)
• Comprehensive Flood and Stormwater Utility Master Plan
• Greenways Master Plan
• UDFCD Drainage Criteria Manual
These various master plan guiding principles and policies helped form the foundation for
the draft Boulder Creek Restoration Master Plan.
ANALYSIS
Icon Engineering was retained by the project team to develop and evaluate alternatives
for Boulder Creek and prepare the draft master plan, which identifies and prioritizes
feasible drainage, flood management, and restoration opportunities. The Executive
Summary of the plan is included as Attachment A and the full plan is available at
http://www.iconeng.com/project/boulder-creek/.
AGENDA ITEM #________PAGE________
The plan provides general guidance for stream and ecological restoration among other
multiple objectives including:
• Identification of immediate project needs;
• Provide general guidance for stream restoration;
• Identify ecological needs and benefits;
• Identify floodplain management strategies;
• Identify transportation improvements at Boulder Creek stream crossings;
• Identify concurrent recreation and open space access planning;
• Identify an improvement prioritization plan;
• Develop cost estimates for financial planning.
The draft Boulder Creek Restoration Master Plan divides the Boulder Creek corridor into
10 different reaches, with reaches 8 and 9 running through the City of Boulder. The draft
master plan recommendations for these two reaches are included below:
Reach 8 – From Valmont Rd. to 30th St.
This reach is approximately 2.3 miles in length and primarily located within the
City of Boulder. The channel characteristics generally include a combination of
riparian habitat, roadway, and trail crossings. Wonderland, Goose, and South
Boulder Creeks enter Boulder Creek within Reach 8, and several small ponds are
located adjacent to the stream. For Boulder Creek, Reach 8 reflects the transition
to an urban flood channel and for the most part, Boulder Creek has been locked in
place through urbanization. The Burlington Northern and Santa Fe (BNSF)
railroad embankment presents a significant obstacle for Boulder Creek and its
connectivity with upstream and downstream floodplain areas. The BNSF crossing
also has significantly less conveyance capacity than the larger span bridges within
Boulder.
Master plan improvements within Reach 8 are comprised of stream restoration,
improving the railroad crossing conveyance capacity, access to the Boulder
Community Health (the hospital), and management of accumulated sediment.
Stream restoration is proposed from the downstream limit of Reach 8 at Valmont
Road through Foothills Parkway. No improvements are proposed for the 55th
Street crossing as the existing bridge structure conveys the 100-year discharge. As
described above, the BNSF railroad is a significant obstacle for Boulder Creek.
The crossing is proposed to be increased to a 180 ft. span bridge to better convey
flood flows and accommodate geomorphic channel conditions.
To ensure safe access to the hospital during major floods, up to the 500-year
event, an alternate access point from 48th Street has been recommended. This
access point would only serve emergency vehicles and would not provide routine
access.
Frequent sediment deposition has been observed throughout Reach 8 along
Boulder Creek and pedestrian trail crossings. Maintenance level sediment removal
projects (up to 200 cubic yards per year) has been incorporated into the master
plan at various crossing locations.
AGENDA ITEM #________PAGE________
Reach 9 – From 30th St. to City of Boulder Limits
Reach 9 extends through the City of Boulder from 30th St. to upstream of
Arapahoe Avenue. This reach also includes the University of Colorado (CU)
Campus, between 17th Street and Folsom. Many roadway crossings exist through
this reach as well as Boulder Creek trail bridges. The Boulder Creek trail also
follows the creek for the entire reach. Many buildings are located within the
Boulder Creek floodplain. Both FEMA and the City of Boulder have designated
additional regulatory zones to manage existing development and redevelopment.
Strategic plans, including CU’s North of Boulder Creek study have also been
developed to identify management strategies to reduce overall flood risk.
Similarly, the City of Boulder is currently in the process of planning for
redevelopment surrounding the Civic Center area, and is evaluating this plan with
respect to flood management.
Master plan improvements within Reach 9 include mitigating flood hazards,
improving access near Boulder Creek, modifying diversions, and sediment
maintenance. Downstream of 28th Street, along Cordry Court, realignment of the
Boulder Creek Trail is proposed to increase conveyance and mitigate the high
hazard conditions near residences. In accordance with City greenway’s
objectives, property acquisition in this area should be considered as a means to
eliminate high hazard designation and improve overall public safety. Near the CU
campus, two new pedestrian bridges are proposed to improve access to the North
of Boulder Creek campus. These bridges, or walkways, will provide emergency
access to areas otherwise susceptible to isolation during flood events.
To mitigate flood hazards along the Boulder Slough, an overflow diversion
structure is proposed at 14th Street. This diversion system will divert flows in
excess of the conveyance capacity of the ditch back into Boulder Creek, reducing
flood risk to adjacent properties. A 48” RCP pipe underneath 14th Street is
proposed to convey the flows from the diversion structure south to Boulder Creek.
Changes to the diversion structure at Broadway are also proposed to
accommodate aquatic and habitat passage.
Similar to other locations, six areas have been identified for annual sediment
removal (up to 200 cubic yards per year) in Reach 9.
No new alternatives have been developed for the Civic Center area in this master
plan study; however changes to Boulder Creek at this location should consider
implementing recommendations discussed in 9.3 Improvement Alternative
Categories, including:
• Removing the Park Central and New Britain building from the 100-year
floodplain, conveyance zone, and high hazard zone;
• Adding conveyance capacity at the Broadway Bridge;
• Overbank grading of Boulder Creek between the Library and Broadway to
reduce high hazard and conveyance zones on the north side of Arapahoe.
It should be noted that with these changes, higher flows along the creek would
persist downstream to west of 30th Street and cause higher 100-year flood levels
AGENDA ITEM #________PAGE________
that would need to be mitigated. Given that these increases in flood levels would
be relatively small, they could likely be mitigated through: select grading of
overbank areas, reducing the potential for debris obstruction at bridges, and/or
increasing conveyance under road crossings.
Although the Civic Area Plan is still being developed, guiding principles and
development constraints related to flood safety were developed to help guide the
development of the Civic Area Plan. This information was compiled into the Civic Area
Flood Information (Attachment C) and includes flood regulatory considerations, flood
policy considerations and site opportunities and flood constraints. It is recommended that
these items be included in the final Boulder Creek Restoration Master Plan.
NEXT STEPS
The draft Boulder Creek Master Plan will be revised to incorporate feedback received.
Following input and a recommendation from WRAB, the Boulder Creek Restoration
Master Plan will be presented to City Council for acceptance. After acceptance, the
master plan will help guide restoration and redevelopment projects within the master plan
area. It will be a planning tool to help identify projects for future funding through the
CIP, grants, UDFCD funding requests and other funding opportunities.
ATTACHMENTS
Attachment A: Executive Summary of the Draft Boulder Creek Restoration Master Plan
Attachment B: Project Overview Map
Attachment C: Civic Area Floodplain Information
Boulder Creek Restoration Master Plan
DRAFT Conceptual Design Report - October 2015
Urban Drainage and Flood Control District
Boulder County, City of Boulder, City of Longmont
7000 S Yosemite St, Suite 120
Centennial, CO 80112
303-221-0802
www.iconeng.com
ICON
engineering, inc.
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
ii
ICONENGINEERING, INC.
7000 S. Yosemite Street, Suite 120, Centennial, CO 80112
303.221.0802 | www.iconeng.com
October 20, 2015
Ms. Shea Thomas, P.E.
Urban Drainage and Flood Control District
Senior Project Engineer, Master Planning Program
2480 W. 26th Avenue, Suite 156B
Denver, Colorado 80211-5304
RE: Boulder Creek Restoration Master Plan – Master Plan Report
Dear Ms. Thomas:
ICON Engineering, Inc. is pleased to submit this Master Plan Report for Boulder Creek. Overall this plan can be used
as a guide for future restoration activities and drainage improvements along Boulder Creek. This submittal
incorporates items from the previous Alternatives Analysis and Recommended Plan, in addition to those discussed
as part of the Selected Plan, provided by the UDFCD on September 14th.
Following issuance of the selected plan, modifications were made to reflect input provided by project sponsors at
the confluence with the Saint Vrain Creek, 95th Street, and near Cordry Court in the City of Boulder. Additional input
was provided at pubic open houses and workshops. These modifications and input are now reflected by the
conceptual design and within the master planning document.
We would like to acknowledge the projects team's assistance in the preparation of this study. This report could not
have been prepared without input from yourself, Boulder County, the Cities Boulder and Longmont, and other
stakeholders to this project.
We believe that this report will provide a solid frame work for the conceptual design phase of this project.
Sincerely,
ICON ENGINEERING, Inc.
Craig D. Jacobson, P.E., CFM
Principal, Project Manager
Brian J. LeDoux, P.E., CFM Jeremy K. Deischer, EI
Project Engineer Project Engineer
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
iii
ES EXECUTIVE SUMMARY
ES.1 Purpose and Objective ...................................................................................................................................... 1
ES.2 Planning Process .............................................................................................................................................. 1
ES.3 Project Area Description .................................................................................................................................. 1
ES.4 Alternative Analysis .......................................................................................................................................... 4
ES.5 Master Plan ...................................................................................................................................................... 4
INTRODUCTION 1.0
Funding and Authorization .............................................................................................................................12 1.1
Background .....................................................................................................................................................12 1.2
Purpose, Scope, Limitations ............................................................................................................................12 1.3
Planning Process .............................................................................................................................................12 1.4
Mapping & Survey ...........................................................................................................................................13 1.5
Data Collection ................................................................................................................................................13 1.6
Acknowledgements .........................................................................................................................................13 1.7
PROJECT BACKGROUND 2.0
Project Area ....................................................................................................................................................14 2.1
Flood History ...................................................................................................................................................14 2.2
September 2013 Flood Event ..........................................................................................................................16 2.3
Previous Studies ..............................................................................................................................................17 2.4
HYDROLOGY AND HYDRAULICS 3.0
Hydrology ........................................................................................................................................................19 3.1
Hydraulics ........................................................................................................................................................19 3.2
Climate Change and Uncertainty ....................................................................................................................20 3.3
STREAM MORPHOLOGY AND EXISTING SITE CONDITIONS 4.0
Stream Classification .......................................................................................................................................22 4.1
Reach Descriptions ..........................................................................................................................................23 4.2
Recreation and Public Access ..........................................................................................................................30 4.3
HISTORIC STREAM EVALUATION 5.0
Background .....................................................................................................................................................33 5.1
Channel Straightening .....................................................................................................................................33 5.2
Sinuosity Changes ...........................................................................................................................................34 5.3
Prior Stream Realignment ...............................................................................................................................34 5.4
Conclusions .....................................................................................................................................................35 5.5
NATURAL RESTORATION OBJECTIVES 6.0
Background .....................................................................................................................................................36 6.1
Characteristics of a Natural Channel...............................................................................................................36 6.2
Typical Channel Geometries ...........................................................................................................................36 6.3
BOULDER CREEK RIPARIAN ZONE 7.0
Background .....................................................................................................................................................38 7.1
Importance of the Riparian Zone ....................................................................................................................38 7.2
Land use and Vegetation Cover Types ............................................................................................................38 7.3
Riparian Zone Vegetation Community and Reference Standard ....................................................................39 7.4
Riparian Zone Post Flood ................................................................................................................................ 39 7.5
Wetlands ......................................................................................................................................................... 41 7.6
Riparian Zone Restoration Guidelines ............................................................................................................ 41 7.7
THREATENED AND ENDANGERED SPECIES, AND AQUATIC HABITAT ASSESSMENT 8.0
Background ..................................................................................................................................................... 43 8.1
Species Protected Under the Endangered Species Act of 1973 ..................................................................... 43 8.2
Migratory Bird Treaty Act ............................................................................................................................... 43 8.3
Aquatic Life ..................................................................................................................................................... 44 8.4
City of Boulder’s Open Space & Mountain Parks (OSMP) Closures ................................................................ 44 8.5
PROJECT FOCAL AREAS / RESTORATION PROJECTS 9.0
Project Focus ................................................................................................................................................... 45 9.1
Criteria and Constraints .................................................................................................................................. 45 9.2
Improvement Alternative Categories ............................................................................................................. 46 9.3
Summary of Project Alternatives .................................................................................................................... 51 9.4
Alternative Cost Estimates .............................................................................................................................. 51 9.5
Qualitative Evaluation Process ....................................................................................................................... 54 9.6
Water Quality Impacts .................................................................................................................................... 54 9.7
RECOMMENDED PLAN 10.0
CONCEPTUAL DESIGN 11.0
Plan Development Overview .......................................................................................................................... 67 11.1
General Recommendation .............................................................................................................................. 67 11.2
Conceptual Design Cost Estimates .................................................................................................................. 68 11.3
Master Plan Description ................................................................................................................................. 68 11.4
Stream Restoration Recommendations .......................................................................................................... 72 11.5
Ecological Recommendations ......................................................................................................................... 72 11.6
Recommended Bridge Improvements ............................................................................................................ 73 11.7
Recreation ....................................................................................................................................................... 73 11.8
PRIORITIZATION 12.0
Stream and Ecological Restoration ................................................................................................................. 93 12.1
Bridge Replacement & Emergency Access ..................................................................................................... 93 12.2
Public Safety .................................................................................................................................................... 93 12.3
Maintenance ................................................................................................................................................... 93 12.4
Prioritization by Jurisdiction ........................................................................................................................... 94 12.5
REFERENCES 13.0
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
iv
List of Tables
Table ES- 1: Project Participants ....................................................................................................................................... 1
Table ES- 2: Peak Flow Summary ...................................................................................................................................... 2
Table ES- 3: Prioritization Summary .................................................................................................................................. 8
Table ES- 4: Cost Estimate Summary (Reach 1-6) ............................................................................................................. 9
Table ES- 5: Cost Estimate Summary (Reach 7-10) .........................................................................................................10
Table 1-1: Project Participants ........................................................................................................................................13
Table 2-1: 2013 Flood Discharge Observations ..............................................................................................................16
Table 3-1: Summary of Boulder Creek Flood Discharges ................................................................................................19
Table 4-1: Existing Reach Properties ...............................................................................................................................30
Table 6-1: Bankfull Flows and Stream Classifications at Locations with Estimated Flows .............................................36
Table 6-2: Target Width/Depth Ratios, and Entrenchment Ratios for Each Stream Classification ................................36
Table 6-3: Geometries for Primary Stream Types at Each Flow Location .......................................................................37
Table 7-1: Post-flood Riparian Zone conditions ..............................................................................................................40
Table 7-2: Representative Native Riparian Zone Tree Species .......................................................................................42
Table 7-3: Representative Native Riparian Zone Shrub Species .....................................................................................42
Table 7-4: Representative Native Riparian Zone Herbaceous Species ...........................................................................42
Table 8-1: Federal Threatened or Endangered Species ..................................................................................................43
Table 9-1: Alternative Ditch Diversion Structures ..........................................................................................................46
Table 9-2: Bridge Information and Replacement Locations ...........................................................................................50
Table 9-3: Summary of Project Alternatives ...................................................................................................................51
Table 9-4: Minimum Improvement Alternative Costs (Reach 1 – 6) ..............................................................................52
Table 9-5: Minimum Improvements Alternative Costs (Reach 7 - 10) ...........................................................................53
Table 9-6: 100-yr Crossing Improvements ......................................................................................................................53
Table 10-1 : Summary of Recommended Plan Project Alternatives (Reach 1-6) ...........................................................60
Table 10-2: Summary of Recommended Plan Project Alternatives (Reach 7 - 10).........................................................61
Table 11-1: 95th Street Interim Conditions Improvements ............................................................................................70
Table 11-2: Recommended Geometries for Primary Stream Types ...............................................................................72
Table 11-3: Recommended Bridge Replacement ...........................................................................................................73
Table 11-4: Conceptual Design Cost Summary by Jurisdiction .......................................................................................73
Table 11-5: Conceptual Design Cost Estimate by Reach (1-6) ........................................................................................74
Table 11-6: Conceptual Design Cost Estimate by Reach (7-10) ......................................................................................75
Table 12-1: Stream Restoration Prioritization Summary ................................................................................................93
Table 12-2: Bridge Replacement & Emergency Access Prioritization Summary ............................................................94
Table 12-3: Public Safety Prioritization Summary ...........................................................................................................94
Table 12-4: Maintenance Prioritization Summary ..........................................................................................................94
Table 12-5: Prioritization Summary by Jurisdiction ........................................................................................................94
List of Figures
Figure ES- 1: Watershed Map ........................................................................................................................................... 3
Figure ES- 2: Master Plan Interactive Map ..................................................................................................................... 11
Figure 2-1: Boulder Creek Watershed Map .................................................................................................................... 15
Figure 3-1: 1%-Annual Chance Projections for the United States, 2060 (AECOM, 2013) .............................................. 21
Figure 3-2: 1%-Annual-Chance Projections for the United States, 2100 (AECOM, 2013) .............................................. 21
Figure 3-3: Colorado Statewide Annual Average Temperature, 1900-2012 (CWCB 2014) ............................................ 21
Figure 3-4: Projected Monthly Precipitation Change for Denver Metro Sub-region .................................................... 21
Figure 4-1: Rosgen Classification System System Schematic (from Rosgen 1996) ......................................................... 22
Figure 4-2: Boulder Creek Reach Map ............................................................................................................................ 24
Figure 4-3: UP Rail Trail ................................................................................................................................................... 32
Figure 5-1: Loss of Stream Length over Time as a Percentage ....................................................................................... 33
Figure 5-2: Loss of Stream Length .................................................................................................................................. 33
Figure 5-3: Depiction of Modification to Channel Meanders ......................................................................................... 34
Figure 5-4: Stream Sinuosity ........................................................................................................................................... 34
Figure 5-5: Change in Stream Sinuosity .......................................................................................................................... 34
Figure 5-6: Straightening Trends in Reach 5 ................................................................................................................... 34
Figure 6-1: Typical Geomorphic Cross-section ............................................................................................................... 37
Figure 6-2: Typical Riffle/Pool Schematic ....................................................................................................................... 37
Figure 7-1: Components of a properly functioning riparian zone .................................................................................. 38
Figure 7-2: Components of a Riparian Community ........................................................................................................ 39
Figure 7-3: Boulder Creek: Example Riparian Reference Standard ................................................................................ 39
Figure 7-4: Example of varying riparian zone widths through the project area ............................................................. 40
Figure 9-1: City of Boulder Civic Area Plan [Reference 65]............................................................................................. 49
Figure 9-2-9-6: Alternative Maps .................................................................................................................................... 55
Figure 10-1-10-5: Recommended Plan Maps ................................................................................................................. 62
Figure 11-1: Conceptual Design Interactive Map ........................................................................................................... 76
Figure 11-2: Conceptual Design Map (Reach 1-3) .......................................................................................................... 77
Figure 11-3: Conceptual Design Map (Reach 4).............................................................................................................. 78
Figure 11-4: Conceptual Design Map (Reach 5-6) .......................................................................................................... 79
Figure 11-5: Conceptual Design Map (Reach 7-8) .......................................................................................................... 80
Figure 11-6: Conceptual Design Map (Reach 9-10) ........................................................................................................ 81
Figure 11-7: Typical Channel Cross Sections ................................................................................................................... 82
Figure 11-8: Typical Bridge ImprovementCross Section ................................................................................................. 83
Figure 11-9: Conceptual Design Rendering – Reach 1 .................................................................................................... 84
Figure 11-10: Conceptual Design Rendering – Reach 2/3 .............................................................................................. 85
Figure 11-11: Conceptual Design Rendering – Reach 4 (Sheet 1) .................................................................................. 86
Figure 11-12: Conceptual Design Rendering – Reach 4 (Sheet 2) .................................................................................. 87
Figure 11-13: Conceptual Design Rendering – Reach 5 (Interim Conditions) ................................................................ 88
Figure 11-14: Conceptual Design Rendering – Boulder Valley Hospital & Boulder Slough Diversion ............................ 89
Figure 11-15: Conceptual Design Rendering – Reach 10 ................................................................................................ 90
Figure 11-16: Typical Details (Sheet 1) ........................................................................................................................... 91
Figure 11-17: Typical Details (Sheet 2) ........................................................................................................................... 92
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
v
Appendices
APPENDIX A - Legal Opinion
APPENDIX B - Meeting Minutes
APPENDIX C - CDOT Hydrology Profile
APPENDIX D - Historic Investigation & Alternate Restoration Alignments
APPENDIX E - Alternative Cost Summaries
APPENDIX F - Riparian Zone and T&E Species Summary
APPENDIX G- Conceptual Design Information
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
1
ES EXECUTIVE SUMMARY
ES.1 Purpose and Objective
The purpose of this master plan is to provide planning guidance to improve resiliency along Boulder Creek from the
confluence with Fourmile Creek, in Boulder Canyon, to the confluence with the Saint Vrain Creek in the City of
Longmont. This plan provides general guidance for stream and ecological restoration among other multiple
objectives including:
• Identification of immediate project needs;
• Provide general guidance for stream restoration;
• Identify ecological needs and benefits;
• Identify floodplain management strategies;
• Identify transportation improvements at Boulder Creek stream crossings;
• Identify concurrent recreation and open space access planning;
• Identify an improvement prioritization plan;
• Develop cost estimates for financial planning.
It is important to note that this master plan provides general guidance for restoration efforts, but it does not re-
evaluate the current 100-year floodplain limits regulated by FEMA. Although the implementation of some proposed
projects presented in this master plan will also improve the regulatory floodplain, the focus of this master plan is to
provide a planning tool for stream and ecological restoration.
Within the City of Boulder, Boulder Creek resembles an urban stream corridor. This master plan does not
comprehensively evaluate Boulder Creek through the City limits. Instead, the plan addresses specific areas of
concern identified by the city staff and other interested parties. General guidance for Boulder Creek is also
presented by the City’s Greenway’s Master Plan [Reference 4, City of Boulder].
ES.2 Planning Process
Planning for this report began in December 2014. The consultant team collected information related to stream
characteristics and existing infrastructure, as well as observations related to 2013 flood event. Data was collected
from multiple sources, including the Federal Emergency Management Agency (FEMA), the Colorado Water
Conservation Board (CWCB), the Urban Drainage and Flood Control District (UDFCD), and the Colorado Department
of Transportation (CDOT), and local counties and municipalities.
Once background information was obtained, the consultant team identified focal areas, and prepared geomorphic
and riparian field assessments. This information was presented to the project team and interested stakeholders at
monthly progress meetings.
Public awareness of the master planning effort was developed through a combination of direct mailings to adjacent
property owners and the development of a project website. The project website included interactive features
allowing individuals to subscribe to a mailing list or to leave site specific comments through an interactive comment
map.
The project team was able to gather input from the public at four separate public meetings and workshops over the
course of the project:
• March 10, 2015: Boulder Creek MDP Public Meeting held in the City of Boulder
• March 18, 2015: Boulder Creek MDP Public Meeting held in Weld County
• September 16, 2015: FEMA Boulder Creek PMR Public Workshop
• September 29, 2015: Boulder Creek MDP Public Meeting held in the City of Boulder
The minutes for all project meetings along with all public comments received can be found in APPENDIX B
.
Table ES- 1: Project Participants
Name Representing
Craig D. Jacobson ICON Engineering, Inc., Project Manager
Brian LeDoux ICON Engineering, Inc., Project Engineer
Jeremy Deischer ICON Engineering, Inc., Project Engineer
Eben Dennis ICON Engineering, Inc., GIS Specialist
Troy Thompson Ecological Resource Consultants, Inc.
David Blauch Ecological Resource Consultants, Inc.
Diane Krzysztof Ecological Resource Consultants, Inc.
Mark Wilcox DHM Design
Shea Thomas Urban Drainage and Flood Control District
Julie McKay Boulder County Creek Recovery & Restoration Program
Manager
Diane Malone Boulder County IT Project Manager
Kristine Obendorf Boulder County Transporation Engineer
Varda Blum Boulder County Floodplain Manager
Yige Gao Boulder County Floodplain Permitting Specialist
Jesse Rounds Boulder County Parks and Open Space Planner
Claire DeLeo Boulder County Parks and Open Space Senior Resource
Specialist
Katie Knapp City of Boulder
Annie Noble City of Boulder
Marianne Giolitto City of Boulder Open Space and Mountain Parks
Dan Wolford City of Longmont
Jonathan Akins University of Colorado
Naren Tayal FEMA
Dan Marcucci Colorado Department of Transportation
Scott Holwick Lyons Gaddis - Attorneys & Counselors
Diana Aungst Weld County
Steve Stanish Town of Frederick
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
2
ES.3 Project Area Description
The Boulder Creek watershed has a drainage area of approximately 440 square miles, and is located within Boulder
and Weld Counties. The majority of the watershed is located within Boulder County. The watershed is bounded to
the west by the continental divide, to the north by the Saint Vrain Creek watershed, and to the south by the Clear
Creek watershed. This study focuses on the main stem of Boulder Creek from the confluence with Fourmile Creek,
approximately 2 miles west of the City of Boulder, to the confluence with Saint Vrain Creek, located within the City
of Longmont. The study encumbers over 24 miles of channel length along Boulder Creek.
Boulder Creek is a perennial stream which generally flows from west to northeast. The study area generally lies
within the South Central Semi-Arid Prairie ecoregion of the Great Plains; while a small portion of the upstream
project reach occurs within the Northwestern Forested Mountain ecoregion of the Southern Rockies. The
topographic elevation ranges from approximately 5,700 feet above mean sea level (AMSL) at the confluence with
Fourmile Creek to approximately 4,800 feet AMSL at the downstream end of the project area.
West of the City of Boulder, Boulder Creek is confined within the steep canyon terrain of Boulder Canyon. Boulder
Canyon generally shares the stream corridor with State Highway 119. East of Boulder Canyon, Boulder Creek enters
the City of Boulder, where the stream reflects more of an urban waterway and greenway than a natural stream
system. Although, through this reach, Boulder Creek does incorporate some degree of natural landscapes, the
encroachment from urban development has occurred over many years. The channel is more confined and
numerous bridges, diversions, and stabilization structures exist along its path. East of the city, within Boulder and
Weld Counties and the City of Longmont, Boulder Creek resembles a plains stream with a broad floodplain.
Although this stretch has fewer bridges than within the urban areas of the City of Boulder, over time, the stream
also has experienced significant channel modifications as a result of farming, diversions, sand and gravel ponds, and
aggregate mining. As a result, in many areas sinuosity has decreased and the stream lacks natural meanders and
bends.
The predominant land cover type within the study area is cultivated cropland, which includes grazing, alfalfa and
other crop production. As noted above, aggregate mining of sand and gravel since the mid 1950’s has visibly shaped
the project area landscape as open water ponds are scattered within the floodplain. Natural vegetation cover exists
within the riparian zone and a variety of wetland habitats also exist. However, riparian and wetland habitat only
occupies a small percentage of the project area. Other land uses include high and low density development within
the City of Boulder, roadways and transportation infrastructure.
The Boulder Creek corridor contains a variety of wildlife, threatened or endangered species, and aquatic habitat.
Both the City of Boulder Open Space and Mountain Parks and Boulder County Parks and Open Space maintain land
restrictions or seasonal closures throughout the project area.
Finally, the floodplain areas along Boulder Creek are regulated by local floodplain administrators and the Federal
Emergency Management Agency (FEMA) over the entirety of the study reach. Regulatory floodplain areas include a
variety of flood zones for riverine and shallow flooding locations. Base Flood Elevations (BFEs), and shaded Zone X
designating the 0.2%-annual-chance, or 500-year floodplain area has been identified within Boulder County. A
regulatory floodway has also been designated along a portion of Boulder Creek from Valmont Road through 61st
Street. Within Weld County the regulatory floodplain consists of an approximate study designation. It should be
noted that the City of Boulder is undergoing a floodplain remapping effort for the reach of Boulder Creek and
Boulder Slough through the city limits. Although the City is still awaiting the formal adoption of the study on the
FEMA FIRM maps, concurrence from FEMA has been given to the technical data, and these changes have therefore
been considered with this master plan where applicable.
A map of the study area can be found in Figure ES- 1: Watershed Map.
ES.3.2 Project Area Hydrology
Hydrologic information for the Boulder Creek Watershed has been documented from a variety of sources, initiating
with the initial U.S. Army Corps of Engineers (COE) Floodplain Information Report in 1969 [Reference 17, U.S. Army
Corps of Engineers], updates by the COE in 1977, more recent Flood Hazard Area Delineation (FHAD) reports
[References 18 & 19, Muller Engineering Company] for the City of Boulder and Boulder County, and current FEMA
Flood Insurance Studies (FIS) [Reference 20, FEMA]. In general, the current regulatory discharges are based on the
1977 COE findings.
In 2009, the City of Boulder initiated an update to the FEMA flood maps. As part of this study, an evaluation was
completed to review and confirm previous hydrologic values [Reference 21, Anderson Consulting Engineers, Inc.].
This evaluation concluded that the regulatory discharges are reasonable.
For the purposes of this master plan, the current FEMA regulatory discharges were maintained for evaluating flood
control aspects of each project alternative. These discharges are presented in Table 3-1, below. It should be noted
that the regulatory discharges presented were confirmed within the referenced regulatory flood studies at each
location.
Table ES- 2: Peak Flow Summary
Location
Fourmile Creek Mouth2 129 2,050 --1 7,960 11,660 21,180
Boulder Creek Canyon Mouth2 130 2,050 --1 7,960 11,660 21,180
6th Street3 130 5 2,200 5,830 8,100 12,150 22,100
55th Street 3 155 5 3,600 7,070 9,300 13,050 22,056
75th Street 4 305 3,350 --1 9,600 13,800 28,800
U.S. Highway 2874 331 2,800 --1 8,600 12,700 27,600
County Line Road4 431 2,850 --1 9,150 13,750 31,700
County Road 16.56 443 --1 --1 --1 13,750 --1
County Road 20.57 446 --1 --1 --1 12,250 --1
1 Data Not Avaliable
2 Floodplain Information Report, Upper Boulder Creek & Fourmile Creek, Gingery Associates, 1981
3 Boulder Creek Floodplain Mapping Study, Anderson Consulting Engineers, Inc., 2013
4 Flood Hazard Area Delineation, Lower Boulder Creek, Muller Engineering Company, Inc. 1983
5 Flood Hazard Area Delineation, Boulder Creek, Muller Engineering Company, Inc. 1983
6 Letter of Map Revision 12-08-0198P at 16.5 Road, Weld County
6 Letter of Map Revision 12-08-1047P at 20.5 Road, Weld County
500-Year
(cfs)
Drainage Area
(sq. mi.)
10-Year
(cfs)
25-Year
(cfs)
50-Year
(cfs)
100-Year
(cfs)
Attachment A: Draft Conceptual Design Report
ICON engineering, inc.
Boulder Creek Master Plan
Project Overview
October 2015
Figure ES-1
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
4
ES.3.3 Project Area Hydraulics
The focus of this study is stream restoration and ecological enhancement along Boulder Creek. The study does not
re-evaluate the current 100-year floodplain limits as regulated by FEMA. For those reasons, a comprehensive
floodplain model has not been generated for this study. However, hydraulic information was collected from a variety
of sources.
ES.4 Alternative Analysis
The majority of the developed alternatives were a part of four main alternative categories:
• Sediment Maintenance: Although restoration activities recommended with this master plan will alleviate
several of these routine problem areas over time, ongoing maintenance, particularly with existing trail
underpasses is still needed. Maintenance activities generally include removal of sediment on an annual
basis.
• Natural Stream / Channel Restoration: In order to allow Boulder Creek to return to a more natural state,
channel restoration projects have been proposed along Boulder Creek. These projects consist of providing
an appropriate channel width, bank full depth, stream sinuosity, overbank floodplain connection, and
ecological / habitat enhancements. Alternatives presented apply the stream restoration principles at
locations with immediate restoration needs and a higher likelihood of implementation in the future. These
projects are generally focused in areas where property has already been acquired, such as public lands, or
locations where changes to private infrastructure could be more easily implemented. However, the
geomorphic and ecological principles presented can be applied uniformly for Boulder Creek, as property and
funding become available.
• Roadway Crossing Improvements: It is typical for roadway crossings of Boulder Creek, particularly east of the
City of Boulder, to experience overtopping while the bridge structure, itself, remains perched over the main
channel. In accordance to Boulder and Weld County criteria, new bridges are required to be elevated above
the 100-year flood level. Overtopping is allowed elsewhere, often hundreds of feet from the bridge
location. Per discussions with Boulder County transportation staff, it was determined that all bridges over
Boulder Creek would need to meet this criteria, at a minimum. Boulder County also requested that
additional alternatives be evaluated for 61st Street, 75th Street, 95th Street, and East County Line Road, which
would convey the 100-year event without overtopping in order to provide emergency services during
flooding. A summary of major roadway crossings along Boulder Creek is presented in Table 9-2: Bridge
Information and Replacement Locations. This table compares the existing bridge elevations and estimated
bridge deck thicknesses with FEMA’s regulatory 100-year water surface elevations along Boulder Creek to
determine if a bridge currently meets criteria. Bridges outside of criteria were selected to be replaced by
this master plan. Bridge replacement recommendations can be found in Table 11-3: Recommended Bridge
Replacement.
• Stream Stabilization and Ditch Diversions: Numerous water diversion points exist in Boulder Creek.
Currently very few of the existing diversions structures also accommodate fish passage or macro-
invertebrates common to the region. Improvements are recommended to retro-fit or rebuild diversions to
satisfy this multi-objective need. Specifically these systems are proposed to be replaced with sloped drop
faces and fish passage measures. Each diversion point would still be required to also maintain adequate
depth to satisfy the decreed discharge for water diversion. These conversions will allow the adjacent
channel to exist in a more natural state while also providing the long term ability to divert water at the
diversion point. Plans to modify any diversion structure should be coordinated with the representative of
the ditch company. The diversion structures proposed to be modified to allow for aquatic and habitat
passage while maintaining the efficiency to divert water to the water rights holder can be found in Table 9-1:
Alternative Ditch Diversion Structures. Drop structures, and other existing stabilization measures, which
present obstruction to fish passage or macro-invertebrate habitat, have also been proposed to be replaced
in a similar manner.
ES.5 Master Plan
The Conceptual Design for this master plan generally follows the alternatives proposed in the recommended plan
with exception of three areas noted by sponsors in the Selected Plan Letter.
At the confluence with the St. Vrain Creek, Boulder Creek has breached along the north bank at a different location
since the Alternative Analysis was submittal. The project plan would reflect maintaining the current stream
alignment with the Boulder Creek / St. Vrain Creek confluence remaining at its existing location. Given the stream
segment and breach occurs on City of Longmont Open Space, improvements in this area will be more related to
maintenance of the existing stream configuration and ecological enhancements.
Flooding events have become more common at 95th Street. At the request of Boulder County, an interim
improvement was developed to help prevent overtopping of the roadway during these more frequent storms, while
still maintain the current bridge configurations and relation to downstream private property. This interim plan
proposes changes to the roadway and integrates with stream restoration needs upstream of 95th Street on City of
Boulder Open Space property. Although the interim condition is presented with the conceptual design, the master
plan improvements and cost estimate reflect a more long term solution.
At Cordry Court, improvements to the Boulder Creek Trail and grading between the trail and the Cordry Court
residences have been added as a recommended improvement to eliminate the high hazard on the residences. In
accordance with City greenway’s objectives, property acquisition in this area could be considered as a means to
eliminate high flood hazard and improve overall public safety.
ES.5.1 Reach 1 – Confluence with St. Vrain Creek to approximately 3,300 ft. upstream of the City of
Longmont
Beginning at the confluence with the Saint Vrain Creek, Reach 1 extends upstream along Boulder Creek for just over
a mile of channel length. All of Reach 1 is contained within Weld County and within City of Longmont Open Space
towards the downstream end. There are no channel crossings within this reach with the exception to a gravel pit
conveyor crossing and several non-formalized low-water crossings for vehicles. This reach includes gravel pit ponds
on either side of Boulder Creek that currently hold water. The riparian area within Reach 1 is approximately 700
feet wide near the confluence with Saint Vrain Creek and narrows to approximately 250 feet at the upstream end.
Beyond the riparian area the floodplain overbanks generally consist of active and fallow farm lands. Sporadic
residential and farm structures are also present within the overbanks along with several petroleum well pads.
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
5
During the 2013 flood, the Saint Vrain Creek breached its banks, avulsing through nearby gravel pit ponds. A further
breach of the pond bank between the Saint Vrain Creek and Boulder Creek redefined the confluence location of the
two streams, moving it approximately 1,300 feet upstream of the original location. In 2015, following spring runoff,
Boulder Creek also breached the same pond bank further west. This again modified the confluence. The streams
continue to change over time. Given the changes are occurring on City of Longmont Open Space property, there is
less risk to private property or infrastructure; therefore, the master plan recommendations reflect maintaining the
creek in-place and providing additional ecological enhancements along the original stream alignment. Gravel pond
spillways have also been recommended for ponds adjacent to Boulder Creek.
ES.5.2 Reach 2 – From approximately 3,300 ft. upstream of the City of Longmont to CR 16 ½
Reach 2 is approximately three miles long and includes bridge crossings at Weld County Roads 20½ and 16½.
Although Reach 2 is located in Weld County, upstream locations are also co-managed through Boulder County
Conservation Easements. Two major diversion structures to the Rural and Idaho Creek ditches are located within
this reach. Disturbances from historic land use practices and channel alterations are widespread. Similarly,
floodplain overbanks throughout Reach 2 generally consist of sand and gravel ponds, and aggregate mining
operations. The channel within Reach 2 is relatively straight as a result of encroachment on both banks.
Master plan improvements through this reach include: replacement of the bridge crossing at Weld County Roads
20½ and 16½ with 180 foot span bridges compatible with baseline geomorphic conditions; retro-fit of the two ditch
diversion structures to accommodate aquatic and habitat passage; modification of a grade control structure for
aquatic and habitat passage; and the installation of gravel pond spillways to reduce the chance of failure during
flood events. Downstream of CO Rd. 16 ½, general stream restoration is also recommended to repair bank erosion
and revitalize Boulder Creek and the surrounding environment. Through this reach Boulder Creek is more confined
by adjacent land uses; therefore a more confined approach to stream restoration would be anticipated.
ES.5.3 Reach 3 – From CR 16 ½ to approximately 5,800 ft. upstream
Reach 3 is located completely within Weld County with the majority of the property managed through Boulder
County Open Space Conservation Easements. This is a short reach with a stream length of only 5,800 ft., spanning a
distance of approximately 3,900 ft. The most significant, and ongoing, problem within Reach 3 occurs upstream of
Weld County Road 16.5, where a breach in the adjacent Williams Reservoir No. 1 diverts flow from Boulder Creek
further to the east. This has led to overtopping of 16.5 Road well east of the bridge.
Master plan improvements in this reach focus on stream restoration and protection of the gravel pit pond from
further failure. Stream restoration improvements propose to relocate Boulder Creek further west, reestablishing
more historic stream alignment and providing additional buffer between the creek and reservoir. Installation of
gravel pond spillways will reduce the opportunity for failure of the reservoir embankment.
ES.5.4 Reach 4 – From approximately 5,800 ft. upstream of CR 16 ½ to U.S. 287
Reach 4 is the longest reach with a stream length of 4.5 miles. Reach 4 is located in both Weld County and Boulder
County with portions of the land owned or managed by Boulder County Parks and Open Space. The downstream
most section is flanked by past aggregate mining activities; the Town of Erie’s sanitary and Re-use facility; and areas
under active gravel operations. The remaining overbanks include active and fallow farm lands and minimal
residential development. There are six stream crossings that span Boulder Creek through Reach 4, some of which
have capacity exceeding the 100-year event. Others are more limited in size, dilapidated, or un-usable. Several
irrigation diversions also exist within Reach 4. Finally, downstream of 109th Street, Boulder County is pursuing a
stream restoration project with the U.S. Army Corps of Engineers. This project extends from 109th Street to Kenosha
Road.
Several different improvements are recommended through Reach 4 including: modifications to ditch diversions;
improvements at roadway crossings; and stream restoration. At the downstream limits, an existing project is
underway to stabilize channel banks adjacent to the Town of Erie’s Re-use facility. Downstream of County Line Road
the conceptual design proposes to modify the Godding A. and D. Plumb Ditch to accommodate aquatic and habitat
passage, in addition to installing gravel pond spillways at adjacent reservoirs. The County Line Road Bridge is
proposed to be improved to a 220 ft. span bridge, improving the crossing to a 100-year conveyance level consistent
with the upstream Mineral Road Bridge. Bridge improvements at County Line Road should also address stream
restoration needs immediately downstream where concrete rubble has been used to stabilize stream banks. No
improvements are proposed for the Mineral Road crossing as the existing crossing already meets the 100-year
conveyance criteria.
Upstream of Mineral Road, stream restoration is proposed throughout the Wheeler Ranch property. Although a
more unimpacted approach restoration can be performed in this area, the final restoration plan should consider
constraints defined by the land owner and needs for the confluence with Coal Creek. Upstream of the Wheeler
Ranch property, channel bank have eroded and exposed the pipe outlet from the Bailey-Kenosha Pond. Stabilization
is proposed along the east bank of Boulder Creek in this area. Upstream of the Bailey-Kenosha Pond, additional
stream restoration is recommended upstream to the proposed U.S. Army Corps of Engineers project limits located
upstream of Kenosha Road. The existing Howell Ditch Diversion, as well as local grade control, are also proposed to
be modified for aquatic and habitat passage. Several gravel pond spillways have been proposed to reduce the
chance of failure during flood events. At Kenosha Road and 109th Street, 180 ft. span bridges are proposed to
increase the conveyance capacity and accommodate geomorphic channel conditions. Alternate stream alignments
for restoration between U.S. 287 and 109th Street should be considered during final design to best balance the
historic stream alignment, with current land uses and transition to the downstream U.S. Army Corps of Engineers
project.
ES.5.5 Reach 5 – From U.S. 287 to approximately 4,200 ft. upstream of 95th St.
This reach is located completely within Boulder County and has a stream length of approximately 3 miles. Within
Reach 5, Boulder Creek crosses 95th Street, which washed out during the September 2013 flood event and nearly
again in 2015. Diversion structures feed the Boulder and Weld County Ditch and the Lower Boulder Ditch. The
overbanks generally consist of inactive gravel pit ponds and both active and fallow farm fields. A vast majority of
this reach follows Boulder County Parks and Open Space, including the Alexander Dawson Open Space, or
conservation easements. Past stabilization efforts have been implemented in this reach, although damage was
extensive following recent floods.
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
6
Master plan improvements for Reach 5 consist of stream restoration, modifications to ditch diversions, and
improving the roadway crossing at 95th Street. No improvements are proposed to the roadway crossing at U.S. 287
as the bridge crossing already exceeds the 100-year conveyance capacity.
Upstream of U.S. 287, stream restoration is proposed through Alexander Dawson Open Space, with aquatic and
habitat passage improvements at the Boulder and Weld County Ditch diversion and upstream grade control. A more
unimpacted approach to restoration is recommended through this area given the open space designation.
Upstream and downstream of 95th Street, stream restoration has been proposed to reestablish geomorphic channel
geometry and improve riparian habitat. Similar to between U.S. 287 and 109th Street, several options for restoration
may exist, including changes to both public and private property. Costs for the master plan improvements at this
location generally reflect the restoration of Boulder Creek to the north of the current alignment, including:
reestablishment of Boulder Creek through the 95th Street Pond (City of Boulder Open Space), new 100-year crossing
of 95th Street at the roadway low point; construction of a new channel and easements across the Boulder Valley
Farms property; and diversion to the current Lower Boulder Ditch at its current location. The master plan
improvements represent a long term solution for the area.
Given the many entities involved and challenges of implementation for the long term solution, Boulder County
requested that an interim solution be developed to address more frequent flooding problems at 95th Street. The
interim solution will maintain the existing bridge, raise the roadway elevation to prevent frequent overtopping, and
provide conveyance from the pond to the bridge through a vegetated spillway. This interim solution is depicted in
Figure 11-8: Interim Improvement at 95th Street Rendering.
ES.5.6 Reach 6 – From approximately 4,200 ft. upstream of 95th St. to 75th St.
Reach 6 is approximately 4.5 miles long and is completely contained within Boulder County. The stream corridor
itself is located on land managed by the City of Boulder’s Open Space and Mountain Parks Division. This reach
appears to remain in a natural state with little encroachments on either overbank. Gravel mining operations on the
south side of the creek have left several small gravel ponds in the floodplain. Hydraulic drop structures exist both
upstream and downstream of 75th Street and the diversion structure for the Leggett Ditch is centrally located.
Master plan improvements for this reach include modifying Leggett Ditch for aquatic and habitat passage and
improving the 75th Street crossing to a 220 ft. span bridge.
ES.5.7 Reach 7 – From 75th St. to Valmont Rd.
This reach is approximately 3.5 miles in length and covers areas of both City of Boulder Open Space and Mountain
Parks and Boulder County Parks and Open Space properties. Through this reach, the channel is nearly completely
flanked by sand and gravel ponds, and mining operations. Most of these operations are no longer active and the
excavated ponds remain full of water. The City of Boulder wastewater treatment plant is located just south of the
creek, upstream of 75th Avenue. The wastewater treatment plant is protected from flooding by a ring levee. Private
stream crossings, minor arterial (61st Street), bike path, and a major arterial (Valmont Road) crossings, are all located
within Reach 7.
Projects within Reach 7 include the installation of gravel pond spillways, protection of the City of Boulder’s sanitary
sewer trunk line, improved roadway crossings, stream restoration, and modification of existing diversion structures.
Seven gravel pit spillways are proposed to protect Walden Ponds near the downstream limit of Reach 7. Several
gravel pond spillways are proposed within the Walden Ponds Wildlife Habitat are and along private ponds within
Reach 7. Stream stabilization and bank protection is proposed to provide additional protection from erosion and
degradation in the vicinity of the City of Boulder’s central sanitary interceptor. These locations will be protected
using grade control structures and bank stabilization.
The master plan improvements do not include stream restoration downstream of 61st Street, as this reach is
currently being addressed by ongoing City of Boulder Open Space and Mountain Parks improvements; however
general restoration guidance for this area is provided. Master plan improvement through this reach do, however,
include modifying the two irrigation ditch diversion structures to accommodate aquatic and habitat passage.
The existing 61st Street bridge is proposed to be replaced with a 220 ft. span bridge to accommodate the 100-year
event. Upstream of 61st Street to Valmont Road, stream restoration has been proposed to reestablish baseline
geomorphic conditions, increase channel sinuosity, and improve overall riparian vegetation and habitat. This reach
is also currently being evaluated by City of Boulder Open Space and Mountain Parks.
The existing trail crossing of Boulder Creek at Old Valmont Road is currently undersized. During the 2013 flood, the
crossing was an obstruction to flow and a significant amount of blockage developed from debris and other items.
This bridge is proposed to be replaced with a 180 ft. span pedestrian bridge to better convey flood flow, debris, and
accommodate geomorphic channel conditions and habitat.
Finally, improvements through Reach 7 include improving the Butte Mill Ditch Crossing across South Boulder Creek.
For this ditch, which originates from Boulder Creek, modifications include siphoning the canal flows underneath
South Boulder Creek in a 54” RCP.
ES.5.8 Reach 8 – From Valmont Rd. to 30th St.
This reach is approximately 2.3 miles in length and primarily located within the City of Boulder. The channel
characteristics generally include a combination of riparian habitat, roadway, and trail crossings. Wonderland,
Goose, and South Boulder Creeks enter Boulder Creek within Reach 8, and several small ponds are located adjacent
to the stream. For Boulder Creek, Reach 8 reflects the transition to an urban flood channel and for the most part,
Boulder Creek has been locked in place through urbanization. The Burlington Northern and Santa Fe (BNSF) railroad
embankment presents a significant obstacle for Boulder Creek and its connectivity with upstream and downstream
floodplain areas. The BNSF crossing also has significantly less conveyance capacity than the larger span bridges
within Boulder.
Master plan improvements within Reach 8 are comprised of stream restoration, improving the railroad crossing
conveyance capacity, access to the Boulder Valley Hospital, and management of accumulated sediment. Stream
restoration is proposed from the downstream limit of Reach 8 at Valmont Road through Foothills Parkway. As
described above, the BNSF railroad is a significant obstacle for Boulder Creek. The crossing is proposed to be
increased to a 180 ft. span bridge to better convey flood flows and accommodate geomorphic channel conditions.
To ensure safe access to the hospital during major floods, up to the 500-year event, an alternate access point from
48th Street has been recommended. This access point would only serve emergency vehicles and would not provide
routine access.
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
7
Frequent sediment deposition has been observed throughout Reach 8 along Boulder Creek and pedestrian trail
crossings. Maintenance level sediment removal projects (up to 200 cubic yards per year) has been incorporated into
the master plan at various crossing locations.
ES.5.9 Reach 9 – From 30th St. to City of Boulder Limits
Reach 9 extends through the City of Boulder from 30th St. to upstream of Arapahoe Avenue. This reach also includes
the University of Colorado (CU) Campus, between 17th Street and Folsom. Many roadway crossings exist through
this reach as well as Boulder Creek trail bridges. The Boulder Creek trail also follows the creek for the entire reach.
Many buildings are located within the Boulder Creek floodplain. Both FEMA and the City of Boulder have designated
additional regulatory zones to manage existing development and redevelopment. Strategic plans, including CU’s
North of Boulder Creek study have also been developed to identify management strategies to reduce overall flood
risk. Similarly, the City of Boulder is currently in process of planning for redevelopment surrounding the Civic Center
area, and is evaluating this plan with respect to flood management.
Master plan improvements within Reach 9 include mitigating flood hazards, improving access near Boulder Creek,
modifying diversions, and sediment maintenance. Downstream of 28th Street, along Cordry Court, realignment of
the Boulder Creek Trail is proposed to increase conveyance and mitigate the high hazard conditions near residences.
In accordance with City greenway’s objectives, property acquisition in this area should be considered as a means to
eliminate high hazard designation and improve overall public safety. Near the CU campus, two new pedestrian
bridges are proposed to improve access to the North of Boulder Creek campus. These bridges, or walkways, will
provide emergency access to areas otherwise susceptible to isolation during flood events.
To mitigate flood hazards along the Boulder Slough, an overflow diversion structure is proposed at 14th Street. This
diversion system will divert flows in excess of the conveyance capacity of the ditch back into Boulder Creek, reducing
flood risk to adjacent properties.
Changes to the diversion structure at Broadway Street are also proposed to accommodate aquatic and habitat
passage.
Similar to other location, six locations have been identified for annual sediment removal (up to 200 cubic yards per
year) in Reach 9.
No new alternatives have been developed for the Civic Center area in this master plan study; however changes to
Boulder Creek at this location should consider implementing recommendations discussed in 9.3 Improvement
Alternative Categories.
ES.5.10 Reach 10 – From City of Boulder Limits to Fourmile Creek
Reach 10 reflects the reach of Boulder Canyon between the City of Boulder and the confluence with Fourmile Creek.
This reach has much steeper overbank slopes and narrower cross section than the reaches to the east. The reach
length is approximately 2 miles and the riparian zone is narrow at less than 100 feet wide. Through the canyon, State
Highway 119 parallels the creek, crossing it twice. The Boulder Creek trail also parallels Boulder Creek along the
opposite bank of the highway. In general, the stream banks are steep and stable, and have been armored with
cobble, rock, and riprap. Boulder County is currently in process of repairing sections of the Boulder Creek trail and
extending the path up to Fourmile Creek.
Reach 10 improvements consist of modifying the Farmers’ Ditch diversion for aquatic and habitat passage.
Restoration of Boulder Creek has also been proposed in areas of disrepair following the 2013 flood event.
Restoration locations have been depicted by the project conceptual design renderings.
ES.5.11 Master Plan Prioritization
In general, projects presented by this master plan are isolated in nature and can be implemented in any order
without affecting adjacent projects upstream and downstream. Stream restoration and ecological enhancement will
be most affected when Boulder Creek has been restored in a consistent manner across the entirety of the study
length.
Since many of the alternatives in this study are not directly comparable, each recommended alternative has been
grouped into a distinguishing category for prioritization. The four categories reflect: stream and Ecological
Restoration, Bridge Replacement & Emergency Access; Public Safety; and Stream Maintenance. Within each
category, projects were ranked in terms of a high, medium, or low priority. Top priority was given to project which
serviced an immediate need; high level of stakeholder interest or collaboration; and presented higher levels of
feasibility for implementation. Lower priority was assigned to locations posing less immediate threat to public
safety, or integrated more long term planning goals.
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
8
Table ES- 3: Prioritization Summary
Reach ID Prioritization by Project Project Type Jurisdiction Priority
HIGH PRIORITY PROJECTS
2 E CO Rd. 16.5 - Replace Bridge with 180 ft. Span Bridge Bridge Replacement Weld County High
2 G Stream Restoration Downstream of CO Rd. 16.5 Stream Restoration Weld County High
3 A Stream Restoration Upstream of CO Rd. 16.5 Stream Restoration Weld County High
3 B Protect Gravel Pond Inlet & Outlet During Storm Flows, Typical Public Safety Weld County High
4 B County Line Road - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge Bridge Replacement Boulder County High
4 G
Stabilize Howell Ditch Diversion System,
Modify Diversion for Aquatic and Habitat Passage Stream Restoration Boulder County High
4 H Kenosha Rd. - Replace Bridge with 180 ft. Span Bridge Bridge Replacement Boulder County High
4 J
109th St. - Replace Bridge with 180 ft. Span Bridge;
Restore Adjacent Channel Bridge Replacement Boulder County High
4 K Stream Restoration Through Wheeler Ranch Stream Restoration Boulder County High
5 H Stream Restoration from Upstream of 95th St. to White Rocks Trail Stream Restoration City of Boulder High
7 E
61st Street - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge Bridge Replacement Boulder County High
7 F Replace Old Valmont Pedestrain Crossing with 180 ft. Span Bridge Bridge Replacement Boulder County High
7 H Protect Sanitary Interceptor Sewer Public Safety Boulder County High
8 C BNSF Railroad - Replace Bridge with 180 ft. Span Bridge Bridge Replacement City of Boulder High
8 F Sediment Maintenance along Boulder Creek Path Maintenance City of Boulder High
9 C North of Boulder Creek Access Improvements Bridge Replacement City of Boulder High
9 D Boulder Slough Mitigation Public Safety City of Boulder High
9 F Sediment Maintenance along Boulder Creek Path Maintenance City of Boulder High
MEDIUM PRIORITY PROJECTS
1 B Protect Gravel Pond Inlet & Outlet During Storm Flows, Typical Public Safety City of Longmont / Weld
County Medium
2 A CO Rd. 20.5 - Replace Bridge with 180 ft. Span Bridge Bridge Replacement Weld County Medium
2 F Protect Gravel Pond Inlet & Outlet During Storm Flows, Typical Public Safety Town of Frederick / Weld
County Medium
4 C
Protect Gravel Ponds / Town of Erie Reuse Pond / Wittemeyer Ponds Inlet & Outlet During Strom
Flows, Typical.Public Safety Town of Erie / Weld County /
Boulder County Medium
4 D Stabilize Bank at Bailey-Kenosha Pond Outlet Stream Restoration Boulder County Medium
4 F
Stream Restoration Through Doniphan, Wittemeyer Ponds, Bailey-Kenosha Ponds, and Open
Space Stream Restoration Boulder County Medium
5 C Protect Boulder Valley Ponds Inlet & Outlet During Storm Flows, Typical.Public Safety Boulder County Medium
5 F Stream Restoration Downstream of 95th Street Stream Restoration Boulder County Medium
5 G
95th St. - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge Bridge Replacement Boulder County Medium
6 B
75th Street - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge Bridge Replacement Boulder County Medium
7 A Protect Walden Ponds Inlet & Outlet During Storm Flows, Typical Public Safety Boulder County Medium
7 B Protect Ponds Inlet & Outlet During Storm Flows, Typical Public Safety Boulder County Medium
7 G Modify Butte Mill Ditch Crossing on South Boulder Creek Maintenance Boulder County Medium
7 I Stream Restoration from Valmont Rd to 61st Street Stream Restoration City of Boulder Medium
8 D Stream Restoration from Foothills Pkwy to BNSF RR Stream Restoration City of Boulder Medium
Reach ID Prioritization by Project Project Type Jurisdiction Priority
LOW PRIORITY PROJECTS
1 A
Stream Maintenance and Ecological Enhancements
City of Longmont Open Space Stream Restoration City of Longmont / Weld
County Low
2 B Replace Existing Grade Control for Aquatic and Habitat Passage Stream Restoration Weld County Low
2 C Modify Rural Ditch for Aquatic and Habitat Passage Stream Restoration Town of Frederick / Weld
County Low
2 D Modify Idaho Creek Ditch for Aquatic and Habitat Passage Stream Restoration Weld County Low
4 A Modify Godding A. and D. Plumb Ditch for Aquatic and Habitat Passage Stream Restoration Weld County Low
4 E DS of Kenosha Rd. - Remove Washed Out Bridge Maintenance Boulder County Low
4 I Replace Grade Control for Aquatic and Habitat Passage Stream Restoration Boulder County Low
5 A Stream Restoration at Alexander Dawson Open Space Stream Restoration Boulder County Low
5 B Modify Boulder and Weld County Ditch for Aquatic and Habitat Passage Stream Restoration Boulder County Low
5 D Modify Grade Control Structures for Aquatic and Habitat Passage Stream Restoration Boulder County Low
5 E Modify Lower Boulder Ditch for Aquatic and Habitat Passage Stream Restoration Boulder County Low
6 A Modify Leggett Ditch for Aquatic and Habitat Passage Stream Restoration Boulder County Low
7 C Modify Diversion for Aquatic and Habitat Passage Stream Restoration Boulder County Low
7 D Modify Green Ditch Diversion for Aquatic and Habitat Passage Stream Restoration Boulder County Low
8 A Stream Restoration from 55th St. to Valmont Drive Stream Restoration City of Boulder Low
8 B Stream Restoration from BNSF RR to 55th St.Stream Restoration City of Boulder Low
8 E Hospital Access Improvements for 500-yr Event Public Safety City of Boulder Low
9 A Cordry Ct, High Hazard & Flood Mitigation Public Safety City of Boulder Low
9 E Modify Boulder Ditches Diversion for Aquatic and Habitat Passage Stream Restoration City of Boulder Low
10 A Modify Farmers' Ditch for Aquatic and Habitat Passage Stream Restoration Boulder County Low
10 B Boulder Canyon Stream Restoration Stream Restoration Boulder County Low
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
9
Table ES- 4: Cost Estimate Summary (Reach 1-6)
Reach ID Description Jurisdiction Reach Length (mi)Capital Eng / Admin / Legal Contingency Total Capital Cost 50-yr O&M Cost
A
Stream Maintenance and Ecological Enhancements
City of Longmont Open Space City of Longmont / Weld County 0.13 39,146$ 11,744$ 9,787$ 60,677$ 9,800$
B Protect Gravel Pond Inlet & Outlet During Storm Flows, Typical City of Longmont / Weld County --261,000$ 78,300$ 65,250$ 404,550$ 1,085$
0.83 300,146$ 90,044$ 75,037$ 465,227$ 10,885$
A CO Rd. 20.5 - Replace Bridge with 180 ft. Span Bridge Weld County --1,792,200$ 537,660$ 448,050$ 2,777,910$ 35,420$
B Replace Existing Grade Control for Aquatic and Habitat Passage Weld County --237,800$ 71,340$ 59,450$ 368,590$ 4,270$
C Modify Rural Ditch for Aquatic and Habitat Passage Town of Frederick / Weld County --290,000$ 87,000$ 72,500$ 449,500$ 4,270$
D Modify Idaho Creek Ditch for Aquatic and Habitat Passage Weld County --290,000$ 87,000$ 72,500$ 449,500$ 4,270$
E CO Rd. 16.5 - Replace Bridge with 180 ft. Span Bridge Weld County --1,792,200$ 537,660$ 448,050$ 2,777,910$ 35,420$
F Protect Gravel Pond Inlet & Outlet During Storm Flows, Typical Town of Frederick / Weld County --5,481,000$ 1,644,300$ 1,370,250$ 8,495,550$ 22,435$
G Stream Restoration Downstream of CO Rd. 16.5 Weld County 0.38 1,054,200$ 316,260$ 263,550$ 1,634,010$ 28,000$
3.14 $ 10,937,400 $ 3,281,220 $ 2,734,350 $ 16,952,970 $ 134,085
A Stream Restoration Upstream of CO Rd. 16.5 Weld County 0.38 1,058,840$ 317,652$ 264,710$ 1,641,202$ 28,000$
B Protect Gravel Pond Inlet & Outlet During Storm Flows, Typical Weld County --261,000$ 78,300$ 65,250$ 404,550$ 1,085$
1.03 1,319,840$ 395,952$ 329,960$ 2,045,752$ 29,085$
A Modify Godding A. and D. Plumb Ditch for Aquatic and Habitat Passage Weld County --290,000$ 87,000$ 72,500$ 449,500$ 4,270$
B County Line Road - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge Boulder County --3,655,197$ 1,096,560$ 913,799$ 5,665,556$ 28,560$
C
Protect Gravel Ponds / Town of Erie Reuse Pond / Wittemeyer Ponds Inlet & Outlet
During Strom Flows, Typical.
Town of Erie / Weld County / Boulder
County --3,915,000$ 1,174,500$ 978,750$ 6,068,250$ 16,030$
D Stabilize Bank at Bailey-Kenosha Pond Outlet 17,089$ 5,126$ 4,272$ 26,487$ 3,220$
E DS of Kenosha Rd. - Remove Washed Out Bridge --69,600$ 20,880$ 17,400$ 107,880$ -$
F
Stream Restoration Through Doniphan, Wittemeyer Ponds, Bailey-Kenosha Ponds,
and Open Space 4,477,600$ 1,343,280$ 1,119,400$ 6,940,280$ 118,999$
G
Stabilize Howell Ditch Diversion System,
Modify Diversion for Aquatic and Habitat Passage --399,308$ 119,792$ 99,827$ 618,927$ 7,490$
H Kenosha Rd. - Replace Bridge with 180 ft. Span Bridge --2,296,800$ 689,040$ 574,200$ 3,560,040$ 28,560$
I Replace Grade Control for Aquatic and Habitat Passage --237,800$ 71,340$ 59,450$ 368,590$ 4,270$
J
109th St. - Replace Bridge with 180 ft. Span Bridge;
Restore Adjacent Channel --2,834,752$ 850,426$ 708,688$ 4,393,866$ 28,420$
K Stream Restoration Through Wheeler Ranch 0.87 2,424,657$ 727,398$ 606,164$ 3,758,219$ 64,399$
4.59 20,617,803$ 6,185,342$ 5,154,450$ 31,957,595$ 304,218$
A Stream Restoration at Alexander Dawson Open Space 0.85 2,378,000$ 713,400$ 594,500$ 3,685,900$ 62,999$
B Modify Boulder and Weld County Ditch for Aquatic and Habitat Passage --290,000$ 87,000$ 72,500$ 449,500$ 4,270$
C Protect Boulder Valley Ponds Inlet & Outlet During Storm Flows, Typical.--1,305,000$ 391,500$ 326,250$ 2,022,750$ 5,355$
D Modify Grade Control Structures for Aquatic and Habitat Passage --237,800$ 71,340$ 59,450$ 368,590$ 4,270$
E Modify Lower Boulder Ditch for Aquatic and Habitat Passage --475,600$ 142,680$ 118,900$ 737,180$ 8,540$
F Stream Restoration Downstream of 95th Street 0.38 1,054,200$ 316,260$ 263,550$ 1,647,495$ 28,000$
G
95th St. - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge --3,778,680$ 1,133,604$ 944,670$ 5,856,954$ 28,560$
H Stream Restoration from Upstream of 95th St. to White Rocks Trail City of Boulder 0.85 2,371,947$ 711,584$ 592,987$ 3,676,518$ 62,999$
2.83 11,891,227$ 3,567,368$ 2,972,807$ 18,444,887$ 204,993$
A Modify Leggett Ditch for Aquatic and Habitat Passage --290,000$ 87,000$ 72,500$ 449,500$ 4,270$
B
75th Street - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge --3,097,220$ 929,166$ 774,305$ 4,800,691$ 28,560$
2.53 3,387,220$ 1,016,166$ 846,805$ 5,250,191$ 32,830$
6
5
4
Boulder County
Boulder County
Boulder County
Reach 4 Total
Reach 5 Total
Reach 6 Total
Reach 1 Total
Reach 3 Total
Reach 2 Total
3
2
1
Attachment A: Draft Conceptual Design Report
Boulder Creek Restoration Master Plan
DRAFT – Conceptual Design for Boulder County, Weld County, and City of Longmont
10
Table ES- 5: Cost Estimate Summary (Reach 7-10)
Reach ID Description Jurisdiction Reach Length (mi)Capital Eng / Admin / Legal Contingency Total Capital Cost 50-yr O&M Cost
A Protect Walden Ponds Inlet & Outlet During Storm Flows, Typical --1,827,000$ 548,100$ 456,750$ 2,831,850$ 7,490$
B Protect Ponds Inlet & Outlet During Storm Flows, Typical --1,827,000$ 548,100$ 456,750$ 2,831,850$ 7,490$
C Modify Diversion for Aquatic and Habitat Passage --290,000$ 87,000$ 72,500$ 449,500$ 4,270$
D Modify Green Ditch Diversion for Aquatic and Habitat Passage --290,000$ 87,000$ 72,500$ 449,500$ 4,270$
E
61st Street - 100-yr Option:
Replace Bridge with 220 ft. Span Bridge --2,843,416$ 853,025$ 710,854$ 4,407,295$ 28,420$
F Replace Old Valmont Pedestrain Crossing with 180 ft. Span Bridge --1,117,813$ 335,344$ 279,453$ 1,732,610$ 28,210$
G Modify Butte Mill Ditch Crossing on South Boulder Creek --235,238$ 70,572$ 58,810$ 364,620$ 4,200$
H Protect Sanitary Interceptor Sewer --511,010$ 153,304$ 127,753$ 792,067$ 8,540$
I Stream Restoration from Valmont Rd to 61st Street City of Boulder 1.18 1,546,781$ 464,034$ 386,695$ 2,397,510$ 87,499$
3.51 10,488,258$ 3,146,479$ 2,622,065$ 16,256,802$ 180,389$
A Stream Restoration from 55th St. to Valmont Drive 0.32 429,200$ 128,760$ 107,300$ 665,260$ 23,800$
B Stream Restoration from BNSF RR to 55th St.0.91 1,194,800$ 358,440$ 298,700$ 1,851,940$ 67,199$
C BNSF Railroad - Replace Bridge with 180 ft. Span Bridge --2,697,000$ 809,100$ 674,250$ 4,180,350$ 28,280$
D Stream Restoration from Foothills Pkwy to BNSF RR 0.49 638,000$ 191,400$ 159,500$ 988,900$ 36,400$
E Hospital Access Improvements for 500-yr Event --46,932$ 14,080$ 11,733$ 72,745$ -$
F Sediment Maintenance along Boulder Creek Path ---$ -$ -$ -$ 839,993$
2.3 5,005,932$ 1,501,780$ 1,251,483$ 7,759,195$ 995,672$
A Cordry Ct, High Hazard & Flood Mitigation 0.06 65,589$ 19,676$ 16,397$ 266,662$ 13,650$
C North of Boulder Creek Access Improvements --3,496,000$ 1,048,800$ 874,000$ 5,418,800$ 69,999$
D Boulder Slough Mitigation --486,385$ 145,916$ 121,596$ 753,897$ 10,815$
E Modify Boulder Ditches Diversion for Aquatic and Habitat Passage --406,000$ 121,800$ 101,500$ 629,300$ 4,270$
F Sediment Maintenance along Boulder Creek Path ---$ -$ -$ -$ 1,259,989$
2.87 4,453,974$ 1,336,192$ 1,113,493$ 7,068,659$ 1,358,723$
A Modify Farmers' Ditch for Aquatic and Habitat Passage --300,000$ 90,000$ 75,000$ 465,000$ 4,270$
B Boulder Canyon Stream Restoration 0.91 696,000$ 208,800$ 174,000$ 1,078,800$ 67,199$
1.64 996,000$ 298,800$ 249,000$ 1,543,800$ 71,469$
25.27 69,397,800$ 20,819,343$ 17,349,450$ 107,745,078$ 3,322,349$
7
Reach 7 Total
Total Costs
City of Boulder
Boulder County
Boulder County
City of Boulder
10
9
8
Reach 8 Total
Reach 9 Total
Reach 10 Total
Attachment A: Draft Conceptual Design Report
ICON engineering, inc.
Boulder Creek Master Plan
Project Overview
October 2015
Figure ES-1
Attachment B: Boulder Master Plan Map
June 2015
Civic Area Floodplain Information
History of Floodplain Activities in the Civic Area
1983 –Boulder Creek Floodplain studies prepared by Muller Engineering Company and used for the
floodplain mapping for the Main Library South Wing project.
1986 - Citizen petition and election for a Library bond for new facilities; the ballot item prohibited
expenditure of funds within the floodway.
1989 - A special election was held in December and it specified that the majority of the bond proceeds
were to be expended in the area between Broadway and 9th and Boulder Creek and Arapahoe and re-
affirming that the flood prohibition still applied to the use of the funds.
1990 – January a Floodplain Development Permit was issued for the new south wing of the library. The
permit, associated study work and floodplain mapping at the time showed that the new facility was not
located within the Boulder Creek floodplain (nor the high hazard zone). Gregory Creek floodplain also
did not impact the site for the library. A condition of this permit required floodproofing be provided for
the existing north wing of the library.
1992 – Library addition completed and Certificate of Occupancy Issued
2009 – November updated Gregory Canyon Creek Floodplain Mapping adopted by City (FEMA accepted
October 2010)
2012 – September updated Boulder Creek Floodplain Mapping adopted by the City (FEMA acceptance
expected in fall 2016). The Main Library North and Center Wings, New Brittan and Park Central remain in
the HHZ, the Main Library South Wing is added to the HHZ, and the Muni Building and the Atrium are
removed from the HHZ.
2013 – Technical Analysis for Floodplain, Wetlands/Riparian Corridor and Water Quality Issues
completed by Wright Water Engineers
2013 – September floods impacted both the West Senior Center and the Main Library. Boulder Creek
experiences a 25 year event and Gregory Creek experiences a 25-50 year event in the Civic Area.
Flood Regulatory Considerations
The Boulder Civic Area Guiding Principles states “The Boulder Civic Area is located within the 100-year
floodplain, and much of the land lies within the High Hazard Zone (HHZ). The city will meet or exceed
existing flood standards, including avoiding placing new structures and parking in the HHA and will be
proactive about planning for and educating about floods.” The city’s existing flood regulations include:
No new buildings intended for human occupancy can be built within the High Hazard
Zone (HHZ).
A building that is touched by the HHZ is regulated as if the entire structure is in the HHZ.
An existing building in the HHZ cannot have additional space intended for occupancy
built nor can the footprint be increased.
Attachment C: Civic Area Flood Information
June 2015
An existing building cannot be improved by more than 50% of the value of the building.
Any improvements that are within the conveyance zone require evaluation and
certification of no impact.
Flood Policy Consideration
Public safety must be considered for flood potential, but does not prohibit activation of areas in the
floodplain or HHZ. A hierarchy of activation and uses related to safety should be considered. Uses that
are outdoors and that do not confine the ability of people to evacuate from the area are safer than
occupied buildings. For buildings, those occupied by the same people on a daily basis (such as office
space) and who are aware of their situation and trained on how to respond is less of a risk than the
circumstance of buildings used for assembly space (such as performance and theater) where occupants
are not routinely in the building, may not have situational awareness nor training on how to respond
during a flood event (or flash flooding).
Site Opportunities and Flood Constraints:
Difference in Risk – While all of the sites in the Civic Area are impacted by floodplain and/or high hazard
zone determinations there are differences in the risks associated with potential flooding for each of the
sites. Future uses of these sites have been considered in response to these different conditions.
West end of Civic Area
Floodplain issues have been a concern in this area and discussed over many years and included in
different studies. Specific regulatory and policy issues are:
Main Library North Wing
This building is impacted by the Boulder Creek 100-year floodplain, conveyance zone and HHZ
designations. The current “island” in the HHZ is created by the blockage of flood flows created
by the location of the building, and the entire location would be HHZ without the building. For
these reasons the site should be managed as a HHZ location.
The flood designations at this site create regulatory constraints that prohibit the expansion of
either the footprint and/or increase in square footage of the building, and also limit the level of
improvements that can be made to the building.
Appropriate uses of the current building should consider the acceptable level of risk with that
use. For example, a regularly used performance/assembly center creates a higher risk to life
safety and is not a use that would be appropriate for this location. More informal uses such a
seating space for the café and small community groups have a lower risk potential. Any use of
this building should include the implementation of an Emergency Management Plan and
associated education and public information necessary to support the activation of the area in
case of flood risk.
The lifespan of this building should be assessed along with its longer term use.
Main Library South Wing
This building is impacted by the Boulder Creek HHZ as it touches a portion of this building;
however the site is not surrounded by the HHZ. This designation does subject the entire building
to city’s high hazard floodplain regulations. It may be possible that mitigation measures for
Attachment C: Civic Area Flood Information
June 2015
Boulder Creek could change the HHZ mapping and remove this building from the designation.
Addition analysis would be required to make a determination on this issue.
West Senior Center
The west edge of this building may be impacted by Gregory Canyon Creek HHZ; however the
rest of the site is not within the 100 year floodplain. Access to this site is impacted by the
Gregory Canyon Creek HHZ that extends east along Arapahoe. While this site is not mapped in
the 100-year floodplain, this facility was impacted during the September 2013 floods and
therefore flooding is a concern separate from the regulatory maps. It is possible that mitigation
work for Gregory Creek could impact this site, and would also lower the flood risk to a portion of
this site and Arapahoe Road. To accomplish this, it is likely that the current building would need
to be removed. Examples of acceptable uses of this site with flood mitigation could be above
ground parking garage or office space.
Muni Building
The 2012 updated Boulder Creek Floodplain mapping removed this building from the HHZ but
the building remains in the 100-year floodplain and the conveyance zone. Additional
floodproofing measures were recommended for this building in a 2013 structural and flood
assessment. It is possible to exit this building without immediately placing people within the
HHZ, which lowers flood risks.
East End Civic Area
Floodplain issues on the east end are different from those found on the west end of the civic area. While
this area is covered by the 100-Year Floodplain of Boulder Creek, the HHZ and conveyance zone
designations are more confined in this area and have decreased in size with the recent mapping update.
The HHZ are along Boulder Creek and also follow Canyon, 13th an d 14th where flood waters are
returning to the creek area.
Atrium Building
The recent floodplain mapping has reduced the HHZ for this property including removing the
building from the HHZ. This building is also not in the conveyance zone, but is within the 100-
year floodplain. Previous floodproofing recommendations include building a flood wall and
adding flood gates around the building, which could impact access and future uses.
13th/14th Block - The developable area in this block is impacted by 100-Year floodplain for
Boulder Creek, but most of the property is neither within the HHZ nor the Conveyance Zone so
fewer regulatory constraints related to flood impact the ability to build new or improve existing
buildings. The street corridors are HHZ in the new mapping, which impacts access during a flood
event; however it is possible to design the sites so that people exiting the buildings are not
placed in the HHZ.
Parking Opportunities
Below grade parking structures are not recommended in the Boulder Creek area due to flood
risk and ground water challenges. Below grade structures are at greater risk for flood damage to
both the structure and the contents and are also a risk for people that may try to leave the area
during a flood. Mitigation for groundwater will also likely increase the cost for both construction
and long term operations of any below grade structure.
Attachment C: Civic Area Flood Information
CITY OF BOULDER
WATER RESOURCES ADVISORY BOARD
INFORMATION ITEM
MEETING DATE: November 16, 2015
AGENDA TITLE: Watershed Sustainability and Outreach Program Efforts Update
PRESENTER/S
Jeff Arthur, Director of Public Works for Utilities
Bret Linenfelser, Water Quality Environmental Services Manager
Russ Sands, Watershed Sustainability and Outreach Supervisor
MaryAnn Nason, Water Conservation and Outreach Coordinator
Lauren Shuler, Infrastructure Resilience and Outreach Coordinator
Candice Owen, Stormwater Quality Engineer
EXECUTIVE SUMMARY
The purpose of this Information Item is to provide the Water Resources Advisory Board (WRAB) a
summary of various sustainability and outreach initiatives that are being developed and implemented by
the Watershed Sustainability and Outreach (WSO) Program that was created in 2014 as part of the Public
Works, Utilities, Water Quality and Environmental Services (WQES) Group. This item does not require
WRAB action and is intended to provide WRAB with a background on the WSO Program and related
initiatives the WSO Program has helped lead.
BACKGROUND:
In early 2013, at a staff presentation on flood outreach, WRAB suggested combining drought and flood
outreach planning efforts to be more adaptive to outreach needs whether it was a wet year or a dry year.
Ironically, 2013 turned out to be both, shifting from drought to flood in a single year. At the same time,
staffing changes in the WQES Group opened new opportunities to combine key programs that could
improve flood and drought outreach as well as allowing for broader planning outside of disaster
preparedness. This led to the development of the Watershed Sustainability and Outreach (WSO) Program.
The WSO Program was formalized in the spring of 2014 with a core mission of enhancing collaboration
and leveraging existing WQES Group Programs including the Water Conservation Program, Stormwater
Quality Program, Education and Outreach Program and related utility efforts. In 2015, as a result of City
Council’s directive and flood related utility rate increases, an Infrastructure Resilience and Outreach
Coordinator position was added to the WSO Program. This expanded WSO Program duties beyond water
conservation, stormwater and education to also include enhanced support for wastewater infrastructure
improvements and community engagement related to reducing Inflow and Infiltration (I&I).
The WSO Program consists of seven temporary and full-time equivalent (FTE) staff and one supervisor.
The Program supports a range of activities including regulatory compliance, fieldwork, construction
project support, sample collection, data analysis, planning, I&I reductions, graphic design work and
community outreach across all three utilities (Water, Wastewater and Stormwater/Flood). The Program
also works to seamlessly integrate city Utility goals into larger planning initiatives through thoughtful
coordination with other Departments, partner organization and regional efforts.
WSO PROGRAM ASSESSMENTS AND IMPACTS
An assessment of the economic, environmental and social impacts of the WSO Program is as follows:
Economic- The WSO Program has and continues to help save the city money through streamlined
Program efforts that allowed new staff to be added without requesting additional budget or FTEs. These
include the following:
• Permanent Stormwater Quality Engineer position for environmental compliance, permitting and water
quality.
• Temporary Education and Compliance Specialist position to assist with on-site spill response, state
reporting and related illicit discharge prevention.
• Temporary Communications Assistant position to assist with graphic design, event planning and
outreach.
Costs avoided by adding staff include reduced risk for regulatory non-compliance which can carry fines
of up to $1,000 per day per infraction. Communication support has also reduced the need for contractor
design and event planning support which can be costly and more time consuming than having in-house
support. The Infrastructure & Resilience Outreach Coordinator position, the only FTE created using new
budget, also works to reduce wastewater treatment (and related energy) costs associated with I&I.
The WSO Program has been able to effectively leverage funds to help make dollars go farther buy
integrating multiple program goals into existing programs, reducing the cost of implementing any single
program on its own.
Environmental- The WSO Program has enhanced environmental compliance in addition to increased
support for the city’s environmental goals as follows:
• Enhanced coordination on stormwater spill response (creek spills; compliance; enforcement).
• Increased outreach on environmental issues which support city values and state requirements.
• New work and pilot studies to evaluate and support improved water quality in Boulder Creek.
• Continued commitment to water conservation and the wise use of water across the city.
• Cross-program partnerships that help meet and coordinate multiple environmental goals.
WSO Program work also supports City Council goals around larger environmental initiates (initiatives?)
such as Boulder’s Climate Commitment, city resilience, etc.
Social- The WSO Program works to support community values and goals including:
• Projects to support water efficiency in low-income housing with Boulder Housing Partners.
• Work to improve water quality in Boulder Creek in support of recreation.
• Enhanced flood outreach for the Community Rating System (CRS) to reduce flood insurance costs.
• Leading regional stormwater protection outreach efforts through the Keep It Clean Partnership
(KICP).
• Support of local food through low-water gardens and related pilot projects.
• Coordination with Boulder Valley School District on environmental education and outreach.
Because the WSO Program is rooted in outreach, most initiatives have a community engagement
component (some of which are mandated by state and/or federal regulation).
ANALYSIS
The creation of the WSO Program is forward-thinking and responsive to larger industry trends where
topics like water quality, water conservation, infrastructure, climate change and watershed health are
increasingly looked at holistically. Addressing multiple programmatic goals through a single effort helps
leverage funds and increase effectiveness. As an example, Stormwater outreach efforts aimed at reducing
runoff can be combined with water conservation outreach that works to reduce outdoor irrigation.
Sometimes over irrigation can also seep into a home’s foundation causing sump pumps to run, opening-
up new conversations around properly directing discharges to storm sewer (or to land), not the sanitary.
In these ways, efforts initiated from one program can be leveraged to address to a broader range of city
concerns at a reduced cost than funding separate, stand-alone outreach efforts.
Aside from programmatic costs, outreach efforts are often accompanied by additional costs for marketing,
graphic design and event planning. In 2008, although minimal at the time, all the Water Conservation
Program, Stormwater Quality Program and Education and Outreach Program graphic design work and
event coordination was contracted. In 2013, contracted Water Conservation and Flood Outreach
marketing efforts alone cost the city roughly $30,000. Today, the WSO Program has reduced costs while
increasing deliverables, using in-house resources to produce nearly 100 graphic design pieces across
utilities in 2015 and organizing multiple, high impact events.
Having in-house capabilities supports, not only desired outreach goals but, helps comply with regulatory
and/or programmatic requirements for community engagement. Stormwater outreach fulfills the city’s
Municipal Separate Storm Sewer (MS4) Permit needs just as designing the city’s required Consumer
Confidence Report fulfills EPA requirements for public notification. Flood safety materials and seminars
help support the city’s CRS score; reducing flood insurance rates for city residents. Of course, CRS
efforts also speak to larger city planning efforts where the WSO Program has been effective at
collaborating to leverage efforts and achieve greater success. Additional examples follow:
• Water, Energy and Climate
The WSO Program focuses on highlighting the connections between water and energy through
partnerships with the city’s Local Environmental Action Division (LEAD) and the Boulder
County’s Partners for a Clean Environment (PACE). For example, the water conservation
commercial assessment tool also built on PACE energy assessment experience to add-in energy
metrics. This close coordination with LEAD and PACE has lead to developing a single PACE
contract each year as well as ensuring that both water and energy are assessed on any PACE audit
that’s performed.
The WSO Program also coordinates to ensure that hydroelectric production and larger water
conservation and water resource goals are woven into city climate planning. In 2015, the WSO
Program helped conceptualize, design and inform the city’s new climate commitment document,
ensuring that water was an integrated component. The draft of “Boulder’s Climate Commitment”
can be found at www.boulderclimate.com, is now open for public comment and is being shared
both locally through city planning efforts and nationally through the Urban Sustainability
Directors Network.
• Climate, 100RC and Water Resources
The inclusion of the city into the Rockefeller Foundation’s 100 Resilient Cities (100RC)
heightened the opportunity for staff collaboration. Resilience builds on the concepts of being
adaptive to both long-term stresses such as aging infrastructure and short terms shocks like flood
and drought. The WSO Program supports resilience efforts by coordinating on events like the
2014 commemorative flood event, and is increasingly working on climate related resilience efforts.
To a larger extent, resilience planning depends on the city’s ability to forecast future climate
impacts such as increases in temperature. This is also critical to water resource planning and WSO
Program efforts to update the city’s Water Efficiency Plan using updated climate projections. As
part of the 100RC efforts, the WSO Program is helping to identify if city policy can be developed
to establish an agreed upon range for temperature projections through 2050 (e.g. 2-6ºF by 2050);
similar to how the city has agreed upon population projections. However, this effort will likely
require larger staff support from multiple workgroups.
Because city staff may need a primer to provide a base understanding of climate modeling prior to
being able to support any policy decision, WSO staff are working to develop a series of climate
workshops. Outside of helping to inform climate projection policy, these workshops aim to pair
staff with climate scientists, perform a tabletop exercise on climate related disaster preparedness
and help layout a framework for scenario planning and vulnerability assessments.
• Drought, Flood and Personal Resilience
Building on water conservation plans to better utilize Center for ReSource Conservation (CRC)
support during a drought, staff coordinated with the CRC to assist with door-to-door flood
outreach in 2014. The success of those efforts and the wet spring of 2015 lead staff to implement
a range of new flood outreach efforts aimed at engaging the community. From pasting a sixty-foot
“don’t stand on bridges” message on one of the bridges in the civic center area to providing free
weather radios to the public, the WSO Program raised awareness that floods can happen again and
won’t always happen the same way.
Beyond awareness, personal resilience was promoted; helping customers understand the steps they
can take to better protect themselves and their homes from disasters. Originally conceived as a
home site-visit to provide recommendations for resilience, staff ultimately landed on a personal
resilience seminar. Free floor drain checks, information on sewer laterals and sump pump
education were focus areas, helping to support city goals around both flood outreach and reducing
I&I.
Because seminar feedback showed that over 80% of attendees would like an in-home assessment if
one were offered, a site assessment option continues to be explored. Staff are in the process of
applying for a federal grant to develop countywide “Resilience Assessments” in partnership with
Boulder County and local flood nonprofit BoCo Strong. Funding would be used to develop
measurable resilience metrics, support I&I reductions and provide customers with landscape
recommendations that help mitigate both minor flooding and drought conditions.
As noted earlier, many of the efforts listed here have increasingly been done with CRS outreach
requirements in mind. Not only have flood outreach materials helped gain CRS points, but
stormwater outreach efforts done for KICP also count for CRS credit; a connection that was not
made in previous years.
• Stormwater Pollution Prevention, I&I, Water Conservation and KICP
Stormwater outfalls provide an interesting nexus for multiple WSO Program projects. Dry
weather flows from outfalls can be indicative of over irrigation or potential cross-connections with
the sanitary sewer and staff is working to help mitigate both. Adding stormwater runoff
messaging to water conservation outreach materials helps make connections to over irrigation.
However, staff also work to identify stormwater and wastewater infrastructure issues. Heavy I&I
loading in the Gunbarrel area initiated smoke testing to look for cross-connections which, if
verified, are sources of I&I as well as potential stormwater pollution from sanitary sewer
overflows.
Specific requirements under the state’s Regulation 85 require specific stormwater outreach to
educate the public about nutrient impacts to surface water. Staff, working on behalf of both the
city and KICP, developed a new campaign to “go easy on the fertilizer,” educating customers
about the negative impacts nutrients can have on streams. The Green is the New PiNK campaign
(which stands for P-N-K or Phosphorus, Nitrogen and Potassium) is now promoted by KICP and
the CRC at landscaping seminars and during irrigation audits. The campaign is also supported as a
component of the CRC’s Garden-in-a-Box program which provides discounted, low-water
xeriscape plants to customers.
In support of local Agriculture, staff has also worked with CRC to offer a low-water, vegetable
garden. Due to concerns of potentially increased fertilizer use, vegetable gardens are a prime
target for nutrient messaging. Of course, the end goal is enhanced water quality regardless of the
pollutant. To that end, a 2016 residential rain garden pilot program is being developed with CRC
to educate customers about the benefits of rain gardens and provide tools and materials for creating
their own rain gardens. This outreach effort helps support greater community knowledge about
water quality, even if small backyard rain gardens may be limited in their practical capacity to treat
runoff.
• Green Infrastructure Opportunities and City Planning
Larger green infrastructure investments may assist with flood mitigation and/or to help meet the
requirements of the Boulder Creek Total Maximum Daily Load for E.coli bacteria, which is aimed
at reducing bacteria in Boulder Creek. However, green infrastructure is a much broader planning
discussion with implications and side benefits related to multiple departments.
While proprietary best management practices (BMPs) like in-ground storm scepters can help, it’s
the above ground BMPs that help support larger community goals such as tree health, habitat or
helping to combat heat island effects. Recommendations to explore green infrastructure options
will be included as part of the water quality component to the 2015 Stormwater Master Plan
update. Additionally, staff contracted with the Brendle Group to evaluate the best green
infrastructure BMPs to install in Colorado’s climate and to help quantify the cross-benefits of
these installations to other city programs.
• Advancing the Conversation Around Watershed Sustainability
Continued local and regional collaboration emphasizes the importance of watershed protection and
sustainability which leverages resources from multiple entities. To promote these efforts
regionally, staff are building on the success of the city-developed 2015 Watershed Summit, by
coordinating a larger, state-wide effort in 2016. The next Watershed Summit is planned for June 9,
2016 at the Denver Botanic Gardens and will cover a range of water related issues. The city has
partnered with Denver Water, the City of Aurora, the One World One Water Center and the
Colorado Water Conservation Board (CWCB) to develop an executive planning team lead by
WSO Program staff. A $10,000 CWCB grant has been awarded to support the event.
NEXT STEPS
The WSO Program will work to continue to advance multiple city efforts through many of the initiatives
noted above. Staff will return to WRAB in December 2015 to discuss specific stormwater program
efforts and again in early 2016 to discuss the Efficiency Plan update and related climate modeling.