HomeMy WebLinkAboutMeeting Packet - Water Resource Advisory Board - 11/19/2012
WATER RESOURCES ADVISORY BOARD MEETING
Monday, 19 November 2012
7:00 p.m.
1777 West Conference Room
1777 Broadway
Agenda Highlights:
1. Call to order. (7:00 p.m.)
II. Approval of minutes from the 15 October meeting (7:01 p.m.)
111. *Public Comment Period. (7:05 p.m.)
IV. Motion to move Matters from Board and Staff to the end of the meeting (7:10 p.m.)
V. Information Item - Update on Thunderbird Lake Pilot Project (7:15 p.m.)
VI. Information Item - Update on Wastewater Treatment Facility Nutrient Compliance Study
(7:45 p.m.)
VII. Information Item - High Hazard Flood Zone Regulations (8:30 p.m.)
VIII. Matters
• From the Board (9:15 p.m.)
o Discussion of 2013 Council Retreat Questions for Boards and Commissions
o Retreat Follow up - Discussion of operating agreements and potential bylaw
amendments
a From Staff (10:15 p.m.)
IX. Discussion about Future Schedule (10:30 p.m.)
X. Adjournment. (10:35 p.m.)
* Public Comment Item
Information: Contact the WRAB Secretary, Laurel Olsen-Horen at (303) 441-3203 or
olsenl(&,bouldereolorado.gav . Packets are available in the reference section of the Main
Library and on-line at http://www.boulderoolorado.gov, Departments, Public Works,
Utilities, Water Resources Advisory Board. Agenda item times are approximate.
WATER RESOURCES ADVISORY BOARD
Upcoming Agenda Items - All Items Tentative
Revised 11-8-2012
December 17, 2012
• Information Item - Critical Facilities Ordinance Update (Coleman)
• Information Item - Water Conservation Rebates (Sands)
• Action Item - Recommendation on Keep it Clean Partnership IGA (Scott)
• Action Item - Response to City Council Request for 2013 Priorities Input
• Matters Item GAC Item - 28`' Street CEAP (Kate Ryan - GAC Representative)
• Action Item - Bylaws Amendments (Arthur)
January 28, 2013 (Rescheduled due to Holiday)
• Information Item - Water Supply Status/2012 Drought Response Debrief (Crean)
• Information Item - Boulder Reservoir ANS/Boulder Reservoir Master Plan Follow Up -
(Wind/Parks & Recreation)
• Action Item - Recommendation on Critical Facilities Ordinance (Coleman)
• Information Item - Discussion of flood safety outreach efforts (Jacobson/Rosato)
• Information Item - 2013 City Council Priorities/Council Retreat Summary (Arthur)
February 25, 2013 (Rescheduled due to Holiday)
• Information Item - Hydroelectric Program Operations/Opportunities (Taddeucci)
• South Boulder Creek Flood Mitigation Study (Bauer)
March 18, 2013
• Last Meeting for Susan lott
April 15, 2013
• New WRAB member/Election of Officers
• WRAB Retreat Scoping
• Information Item - 2014 Budget Process Overview
May 20, 2013
• WRAB Retreat Follow Up
• Information Item - 2014 Capital Improvements Program
June 17, 2013
• Action Item - Recommendation on 2014 Capital Improvements Program
July 15, 2013
• Water Conservation Futures Shady
Upcoming Items/Not Scheduled
• Commercial/Industrial/Institutional Accounts (Sands)
• Fluoride in drinking water (Linenfelser/Crittenden)
• Public Works Design and Construction Standards (Schum)
• Update on Partnership for Clean Water (Emarine)
• Skunk Creek Flood Mapping Update (Coleman)
• Upper Goose Creek/Two Mile Canyon Creek Flood Mapping Update (Noble/Bauer)
• Boulder Slough Flood Mapping Update (Coleman)
• Backflow Prevention Program (Leoni)
• Utility Revenue Stabilization (Baird/Sands)
• Technology and Benchmarks (Crittenden/Douville/Crean/Harberg/Gallo)
• Boulder Creek E-coli TMDL Implementation Plan/East Marine Street BMP
Implementation (Scott)
• Water Supply/Climate Change (Taddeucci)
• WWTF Activated Sludge Upgrade/Removal of Emerging Contaminants
(Linenfelser/Douville)
• Update on Civic Area Planning Process
• WWTF - Tour of facility upgrades (Douville)
CITY OF BOULDER, COLORADO
BOARDS AND COMMISSIONS MEETING MINUTES
Name of Board / Commission: Water Resources Advisorv Board
Date of Meetin : 15 October 2012
Contact Information of Person Preparing Minutes: Laurel Olsen-Horen: 303-441-3203
Board Members Present: Susan lott, Kate Ryan , Chuck Howe, Vicki Scharnhorst, Dan Johnson
Staff Present: Jeff Arthur, Director of Public Works for Utilities
Bob llarberg, Engineering Project Management Coordinator
Bret Linenfelser, Water Quality and Environmental Services Coordinator
Chris Douville, Coordinator of Wastewater Treatment
Annie Noble, Greenways Coordinator
Kurt Bauer, Engineering Project Manager
Cole Sigmon, Process Optimization Specialist
Laurel Olsen-Horen, Board Secrete.
Meeting Type: Regular
Agenda Item 1 - Call to Order [7:04 p.m.]
This meeting was called to order at 7:04 p.m.
Agenda Item 2 - Approval of the 17 September 2012 Meeting Minutes: [7:06 p.m.]
Motion to approve as presented by: Ryan; Seconded by: Howe
Motion Passes; 5:0
Agenda Item 3 - Public Participation and Comment [7:07 p.m.]
Public Comment:
Jitn Medall: Mr. Medall promoted a new water treatment technology for effluent water reuse to the board.
It was suggested to Mr. Medall to work at the state level to work on changing legislature on water reuse to
allow for such technology to take hold in Colorado.
Agenda Item 4 - Motion to move Matters from the Board and Staff to the end of the WRAB meeting
Moved by: Howe, Seconded by: Ryan
Vote: 5.0
Agenda Item 5 - Public hearing and WRAB consideration of a recommendation to City Council
regarding an update to the Multi-Hazard Mitigation Plan 17:17 p.m.]
Kurt Bauer presented item to the board.
Executive Summary from Packet Materials:
The City of Boulder first developed a Multi-Hazard Mitigation Plan in 2008 to better protect people and
property from the effects of natural hazard events. The plan also provided eligibility for federal disaster
assistance grants and earned points for the National Flood Insurance Program (NFIP) Community Rating
System (CRS). To remain eligible for federal funding and CRS points, the Federal Emergency
Management Agency (FEMA) requires the plan to be updated every five years.
The city in conjunction with AMEC consulting firm and the Hazard Mitigation Planning Committee
(HMPC) developed the 2012 five year plan update. The HMPC is comprised of key city, county and other
government and stakeholder representatives. The goals of the plan. include:
1. Increasing community awareness
2. Reducing vulnerability to natural hazards
3. Increasing interagency capabilities and coordination.
The five year update included updating the natural hazard risks and capabilities and developing a new list
of mitigation actions. Based on the updated analysis, the most significant natural hazards are floods,
drought, dam failure, wildfire and pandemic flu.
Sixteen mitigation actions were carried forward from the 2008 plan and 17 new actions were identified.
The mitigation actions were developed to address the most significant natural hazards with the exception of
dam failure (the city coordinates with the State to ensure that dams are safely maintained) and pandemic flu
(considered a regional or state-wide issue). Twelve of the 33 proposed action items relate to flood
mitigation. Each action is described in the plan including the responsible office, priority ranking, estimated
cost, potential benefits, funding sources and anticipated schedule.
The 2012 update will be reviewed by the Colorado Water Conservation Board (CWCB) and FEMA_ The
final version will be resented to City Council in early 2013 with a request for acceptance. Following
WRAB Minutes
15 October 2012
Page No. 1
acceptance, the plan will be reviewed on an annual basis and updated again in 2018.
Public Comment:
Connie Leserman: Mrs. Leserman's property is currently not in the high hazard floodplain. Under the
proposed changes to the high hazard floodplain, Mrs. Leserman's property would be included. Under the
Boulder Revised Code, 9-3-5, and 9-3-8, reconstruction of the property after a flood event may not be
possible under the high hazard classification. Mrs. Leserman has concerns surrounding the validity of the
code and its purpose. Mrs. Leserman was instructed by City Council to ask the board to add it to their list of
priorities for council to consider for next year's work plan during their January recess.
WRAB Discussion Included: [7:49 p.m.]
• Why was overall dam safety not included in the MHMP? Staff response: It was decided not to
include dam safety specifically in the MHMP due to the fact that there are State and Federal
(FERC) requirements surrounding dam safety that the city already has to comply
• The board asked some clarifying questions to better understand the Multi-Hazard Mitigation Plan.
Motion: Moved by: Ryan, Seconded by: Iott, Move that WRAB recommend to City Council to accept
the flood and drought related action items in the 2012 Multi-Hazard Mitigation Plan.
Vote: 5.0
Agenda Item 6 - Update on Wastewater Treatment Facility Regulatory Requirements [7:54 p.m.]
Bret Linenfelser and Chris DouviIle presented item to the board.
Executive Summary from Packet Materials:
The City of Boulder (city) 75`h Street wastewater treatment facility (WWTF) received a new Colorado
Discharge Permit System (CDPS) discharge permit which became effective May 1, 2011. Permit limits of
most concern in the new permit are low daily maximum ammonia limits, daily maximum nitrate limits, and
a low monthly average arsenic limit. A monitoring only requirement for temperature is also included in the
permit and could lead to a temperature effluent limit in the future. A copper temporary modification is
effective in the permit until December 31, 2015 to address potential non- compliance with copper effluent
limits and allow time to develop a site-specific approach for compliance. The CDPS permit includes a
compliance schedule for ammonia, nitrate, arsenic, temperature, and copper, and multiple progress reports
are also required.
In June 2012, the Colorado Water Quality Control Commission (Commission) approved technology-based
nutrient effluent limits, through Regulation 85, for total inorganic nitrogen (TIN) and total phosphorus
(TP). The Conunission also approved restrictive water quality standards, through Regulation 31, for
nitrogen, phosphorus, and chlorophyll a (algae). Both Regulation 85 and Regulation 31 will impact the 75"
Street WWTF, but at different times. Regulation 85 requirements will be implemented into the next CDPS
discharge permit, possibly in 2016. Regulation 31 requirements become effective May 31, 2022 and
resulting effluent limits would be implemented into the 75'h Street WWTF permit around 2026 (year
estimated based on 5-year permit renewal cycles).
Staff initiated technical and regulatory studies to evaluate options for meeting future effluent limits for the
current CDPS permit and future nutrient regulations under Regulation 85 and 31. Planning level cost
evaluations are also being completed and should be available in November 2012 for current permit limits
and Regulation 85 and 31 requirements.
The WWTF regulatory update is being presented as an information item and formal action by WRAB is not
required. Compliance with, and monitoring of, future regulations will require WWTF capital
improvements and require staff time to monitor regulatory developments by actively participating in state
work groups. There are significant cost implications to meet future regulations and those costs will be
reflected in the CIP budget, which will require WRAB consideration. This update provides the regulatory
basis for future capital improvements and provides WRAB with an opportunity to ask questions and
provide input on WWTF compliance strategies.
WRAB Discussion Included: [8:48 p.m.]
As this was an informational item, the board thanked staff for a very good and infonnative presentation.
WRAB Minutes
15 October 2012
Page No. 2
Agenda Item 7 - Matters [9:08 p.m.]
From the Board:
Board member I Lowe brought up the below matter(s):
• High-Hazard Flood zone: WRAB needs to initiate this discussion and review. Staff response: staff
can draft an informational item to help WRAB evaluate the issue. WRAB could include the issue
in its annual letter to City Council on priorities.
Board member Ryan brought up the below matter(s):
• The Boulder Canyon Hydro Modernization Project Celebration was a couple of weeks ago. Thank
you to staff.
Board member Iott brought up the below matter(s):
• Review of the WRAB retreat agreements and actions summary.
From Staff: 19:39 p.m.]
• Boating on Barker - The Town of Nederland, Board of Trustees issued a request to City Council
to have them direct staff to negotiate a MoU between the two entities.
• CU reuse - Council authorized a signature of the MoU, however the Colorado Department of
Public Health and Environment contacted the city with concerns. Mainly, from their point of view,
CU has not frilly contacted them to obtain the proper permits to implement this type of system.
• Waste Water Bond ratings - overall improvement in the city's rating since 2005.
• City Council meeting - at tomorrow's city council meeting the annual budget
Agenda Item 8 - Discussion on Future Schedule [10:10 p.m.]
Staff will work on a briefing for WRAB for the High Hazard Mitigation Plan. May not be available to the
board until the December meeting.
Agenda Item 9 - Adjournment 110:17 p.m.]
There being no further business to come before the Board at this time, by motion regularly adopted, the
meeting was adjourned at 10:17 p.m.
Motion to adjourn by: Johnson; Seconded by: Ryan
Motion Passes 5:0
Date, Time, and Location of Next Meeting:
The next WRAB meeting will be Monday, 19 November 2012 at 7:00 p.m., in the 1777 West Conference
Room of the city Municipal Building located at 1777 Broadway, unless otherwise decided by staff and the
Board.
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.
WRAB Minutes
15 October 2012
Page No. 3
CITY OF BOULDER
WATER RESOURCES ADVISORY BOARD AGENDA ITEM
MEETING DATE: November 19, 2012
AGENDA TITLE: Thunderbird Lake at Admiral Arleigh Burke Park Pilot Project Update
PRESENTERS:
Jeff Arthur, Director of Public Works for Utilities
Bret Linenfelser, Water Quality and Enviromnental Services Coordinator
Jeff Dillon, Parks and Planning Superintendent
EXECUTIVE SUMMARY
In 2007, members of the community contacted the City of Boulder (city) Parks and Recreation
Advisory Board (DRAB) and City Council requesting that the city increase the water level of
Thunderbird Lake and improve its aesthetic quality. Parks and Recreation developed
management options for consideration and the decision was made to provide supplemental water
to Thunderbird Lake as part of a pilot project. Details on the history of Thunderbird Lake, and
management options considered, are documented in the February 27, 2012 Water Resources
Advisory Board (WRAB) agenda, which can be found at the following link
www.bouldercolor,ido.yov/files/Utilities/WIZAB/2012/2012-2/A«eiida 5 - Thumlerbird.pdP
In early 2012, at the recommendation of Utilities and Parks and Recreation staff, the PRAB,
WRAB and City Council supported continuing the Thunderbird Lake pilot project through 2012,
which is one year longer than the initial pilot project schedule. Parks and Recreation recently
completed the fourth and final year of the Thunderbird Lake pilot project and a summary of the
2012 pilot project findings, and recommendations, is provided in Attachment A.
Parks and Recreation recommends moving forward with using an adaptive management
approach to managing Thunderbird Lake with a water surface elevation goal between 5314 feet
and 5312 feet. Studies completed over the 2012 season support that a water surface elevation in
the range of 5314 feet to 5312 feet can be achieved without the addition of potable water. Parks
and Recreation proposes to monitor Thunderbird Lake in future years and will coordinate with
Utilities if it is determined that potable water is needed to meet Thunderbird Lake management
goals. Parks and Recreation is not requesting any special considerations related to potable water
use, water budgets, or Plant Investment Fee. As a result, no formal action by the WRAB is
requested at this time.
COMMUNITY SUSTAINABILITY ASSESSMENTS AND IMPACTS
AGENDA ITEM # V ; PAGE 1
• Economic - During the pilot project, Parks and Recreation has not been charged a Plant
Investment Fee, but has been assessed charges for water use above and beyond the
established water budget. Under the proposed plan, Parks and Recreation is not requesting to
utilize potable water. The proposed plan will result in reduced water demands and associated
savings to the water utility and will have minimal effect on overall revenues and
expenditures. No associated adjustments to customer rates are proposed.
• Environmental -Improved lake water quality and aquatic habitat will enhance the overall
environmental function of the lake.
• Social - The proposal to maintain a high quality water body without the use of potable
water appears to address the needs of the utilities customers who enjoy the lake without
impacts to other customers.
PUBLIC PROCESS AND COMMENT
Thunderbird Lake management options were presented to PRAB on September 22, 2008 and to
WRAB on January 12, 2009. Management options were also presented to City Council in a
study session held on February 19, 2009. A recommendation was made by WRAB (February 27,
2012), PRAB (April 23, 2012) and City Council (May 29, 2012) to continue the pilot project
through 2012 and the recommendation was approved by both Boards and City Council.
BACKGROUND
In 2006, after several years of reduced or no natural water supply to the Thunderbird Lake,
ecological conditions developed in the lake that resulted in a fish kill, stagnant and odiferous
water and algae blooms covering the lake surface. In 2007, members of the community
contacted the PRAB and City Council requesting that the city increase the water level of
Thunderbird Lake and improve its aesthetic quality. Parks and Recreation developed
management options for consideration, which included
• Option A: No Additional Action
• Option B: Adaptive Management
• Option C: Potable Water - one fill per year
• Option D: Potable Water - multiple fills per year
• Option E: Groundwater Well
• Option F: Retrofitted / Lowered Tile Drain
• Option G: Stormwater
• Option 11: Diversion from Bear Canyon Creek
Upon consideration of all of the options, the PRAB, at their September 22, 2008 meeting, voted
in support of Option B - Adaptive Management with no supplemental water. At the WRAB
January 12, 2009 meeting WRAB recommended Option D - Potable Water - multiple fills per
year. The WRAB also encouraged Parks and Recreation to investigate alternative non-potable
options for filling the lake. At the February 17, 20009 City Council meeting, City Council
AGENDA ITEM # V ; PAGE 2
supported the WRAB's recommendation of Option D. City Council also directed Parks and
Recreation staff to begin a three year (through 2011) pilot project at Thunderbird Lake to
evaluate the effectiveness of implementing Option D.
A three year pilot project was initiated in 2009 and studies were conducted, and data collected,
through the 2011 season. In early 2012, at the recommendation of Utilities and Parks and
Recreation staff, the PRAB, WRAB and City Council supported continuing the Thunderbird
Lake pilot project through 2012. Parks and Recreation recently completed the fourth and final
year of the Thunderbird Lake pilot project and a summary of the 2012 pilot project findings, and
recommendations, is provided in Attachment A.
Thunderbird Lake history, detail on the eight management options considered, and summaries of
study finding including historic potable water use at Thunderbird Lake, are documented in the
February 27, 2012 Water Resources Advisory Board (WRAB) agenda, which can be found at the
following link w4vtiv.bouldercolorado. ov/tilesiUtilitieslWIZAB/201212012-21Agenda 5 -
Thunderbird.pdf
ANALYSIS
During the 2012 season, Thunderbird Lake was monitored to evaluate water quality and water
levels while minimizing the addition of potable water. Through the erratic year of weather,
which included record heat and low precipitation, Thunderbird Lake maintained a median
surface elevation of 5313.6 feet, with a range of 5314 feet to 5312.5 feet, for most of the
summer. These water surface elevations were accomplished with a limited addition of potable
water, compared to 2009 through 2011, and the water surface elevation was primarily supported
by local groundwater levels.
The water surface elevation goal of 5314 feet to 5312 feet was achieved in 2012 without having
to add potable water after July 20th, even with a very dry September and October. In addition,
lake water quality, including good clarity, limited algae and no odors, was also accomplished.
Based on 2012 pilot study results, Parks and Recreation feels a future lake water level goal of
5314 feet to 5312 feet can be accomplished based on local groundwater levels and no addition of
potable water. Results of the 2012 season pilot project, and Parks and Recreations'
recommendations, are provided in Attachment A.
NEXT STEPS
Based on the results of the Thunderbird Lake pilot project Parks and Recreation proposes to
move forward with an adaptive management approach to managing Thunderbird Lake, which
includes relying on local groundwater levels to maintain a lake level goal in the range of 5314
feet to 5312 feet. If Parks and Recreation determines that the addition of potable water is needed
to achieve Thunderbird Lake management goals, Utilities will work with Parks and Recreation
on an appropriate Plant Investment Fee and water budget for Thunderbird Lake based on the
amount of water needed. If a future request is made to utilize water outside of the existing water
AGENDA ITEM # V ; PAGE 3
t}ud~ct methodology and f'ec structure, it is anticipated that WRAB will be provided with an
opportunity to wei41h in on that reducst prior to City Council umsideration.
ATTACHMENTS
A - Parks and Recreation memorandum - Update on Thunderbird Lake Monitoring, and
RecowinC'IOC}CI NC-/ SfehS.
AGF;NDA ITEM # V ; PAGE 4
OF Q D1jZ
3198 Broadway - Boulder, Colorado 80304-2644 U
Tel. 303-413-7200 • Fax 303-413-7201
www.botildereolorado.gov/parks-recreation
Parks & Recreation
Attachment A
MEMORANDUM
To: Jeff Arthur, Director of Public Works - Utilities
From: Kirk Kincannon, CPRP, Director Parks and Recreation
Jeff Dillon, Parks and Planning Superintendent
Jeff Haley, Planning Manager
Matt Claussen, Urban Resource Manager
Date: November 19, 2012
Subject: Update on Thunderbird Lake Monitoring and Recommended Next Steps
EXECUTIVE SUMMARY
The Parks and Recreation Department has completed a fourth year as an extension of a three-
year pilot project to improve the water quality and water level for Thunderbird Lake, a man
made lake located at Burke Park. The goal. of the extended fourth year was to review the water
table data provided as a result of the test wells and previous years monitoring to determine if an
acceptable lake surface level could be maintained within new parameters of elevations between
5314 and 5312 without the addition of millions of gallons of potable water.
The Pilot Project was initiated in 2009 utilizing potable water through multiple fills per year in
response to the City's effort to resolve low water levels that resulted in the associated issues of
diminished aesthetics, aquatic vegetation, pests, and odors at Thunderbird Lake. The three-year
pilot program has shown that a constant lake surface area can be maintained and that water
quality can be improved by adding potable water. Ilowever, the high elevation of 5315 constant
lake surface cannot be maintained within the allocated water budget, which is contrary to the
department's and city's long term sustainability goals.
An update regarding the status of the lake and the annual use of 4-6 million gallons of water to
improve and maintain the site's water quality was provided to the Water Resource Advisory
Board (WRAB) on February 27, 2012 and to the Parks and Recreation Advisory Board (PRAB)
on April 23, 2012. At that time staff indicated that the pilot program would be extended through
the 2012 season while alternatives that would reduce water demands and improve long term
sustainability were evaluated. City Council accepted this approach.
The results of the 2012 reduced fills indicated that lake surface levels could be maintained at a
range of 5314 to 5312 with a median range of 5313.6. This was achieved with minimal water
Parks and Recreation-- The Benefits Are EndleSS! TM
fills of 1.3 million gallons with no water additions after.luly 20 of this year. Based on these
findings it is the Department's belief that a lake surface level can be maintained without the
addition of potable water. Water and visual quality can be managed through Adaptive
Management Practices that will ensure a lake surface area equal to that which was achieved
during the 2012 season.
In addition the department is working in partnership with the Horizon K-8 School, the University
of Colorado's (CU) Environmental Design School, Growing Up Boulder and local residents to
develop options for a sustainable approach that includes an outdoor education component in
Admiral Burke Park and Thunderbird Lake. The results of these efforts will be incorporated into
a final design plan for Burke Park that will address public access as well as outdoor learning
opportunities for all ages at the park/school site.
FISCAL IMPACT
During the 2009 budget process, $200,000 was included in the Capital Improvement Program
(CIP) budget for potential actions at Thunderbird Lake. Project costs have included wetland
permitting and mitigation; construction of water delivery system; installation of a de-chlorination
system; installation of an aeration system; groundwater analysis; site operations and other
associated project costs. Total annual project costs, including potable water expenditures, are
detailed below:
YEAR TOTAL COST POTABLE WATER COST
2009 $93,000 $12,000
2010 $90,000 $66,000
2011 542,000 $31,000
2012 $36,500 $158
It is important to note that the potable water expenditures were a considerable portion of the
annual expenditures during the pilot period as compared to 2012.
COMMUNITY SUSTAINABILITY ASSESSMENTS AND IMPACTS
• Economic: Burke Park, including the Thunderbird Lake natural area, compliments the
residential area for housing and real estate values. The location is an attractive feature of the
neighbourhood and with the redesign effort the school/park site will improve property values
as well as surrounding economic opportunities for local businesses with eco-related services
such as youth summer nature camp.
• Environmental: Thunderbird Lake is currently in a man made, but functional status with
wetlands, improved water quality, vegetative and aquatic habitat for wildlife species. Local
hydrological data shows suitable water table levels to maintain a sustainable water supply to
maintain lake water levels at 5312 to 5313 elevation without supplemental additions. The
current level of water addition for 2012 has been consistent with the sustainability goals. The
extended 2012 pilot project demonstrated that a lake surface could be maintained at a level of
5312 to 5313 with minimal water fills and a new park design is being developed with the
community this year that is aimed at creating a sustainable design model.
• Social: Burke Park has a half-mile service area as a neighborhood park andsetves
approximately 3,400 residents. It sits adjacent to and shares a boundary with Horizons K-8
Charter School. Community members have spoken about the benefits the lake feature
provides to residents and the nearby school children. Residents also appreciate the value the
lake provides to wildlife and viewing opportunities. The school children and parents have
expressed a strong desire to link the school to the park and lake through outdoor learning
opportunities that are consistent with higher education and learning as part of place-based
environments.
BACKGROUND
The Thunderbird Lake Pilot Project was initiated in 2009 in response to the City's effort to
resolve low water levels and associated issues of aesthetics, aquatic vegetation and odor at
Thunderbird Lake. The lower water level resulted from a decreasing water table and severe
regional drought conditions experienced in 2001 and 2002. After several years of reduced or no
water supply to the lake, ecological conditions developed that resulted in a lake fish kill, stagnant
and odorous water as well as algae and vegetation blooms covering the lake surface. In 2007,
community members requested that steps be taken by the City to improve the undesirable lake
conditions.
As part of the Parks and Recreation Department's extended pilot program in 2012 the lake
continues to be monitored with appropriate management actions taken to ensure water quality
and adequate water levels are maintained while minimizing the addition of potable water.
Through the erratic year of weather (record heat and low rain fall), the lake has maintained a
level of 5314 to a low of 5312.48 with a median of 5313.6 for most of the summer. This was
accomplished with limited potable water fills while the natural lake surface level supported by
groundwater was observed. 1,297,320 gallons of potable water have been added to the lake this
year through July 20`n
The quality of the water has been of consistent clarity and free from algae and odors. During this
year, the following has been completed for the lake: (a) five treatments of Aquatron and Waste
sludge reducer; and (b) continued aeration. Wildlife, including waterfowl, small mammals and
birds, has been observed in and around the lake. The aquatic native species that make up the
wetland buffer between the lake and the grass areas have maintained a consistent coverage and
view sheds are still open from three specific areas around the lake. These view sheds will be
maintained as part of the wetland permits for the area and enhanced as part of the planned future
development.
The department, in cooperation with the neighboring Horizon Charter School, has discussed
joint use of the site and development of an outdoor learning laboratory that integrates the
school's science and environmental curriculum with both the Lake and adjoining Admiral Burke
Park (Park). Through a partnership with the University of Colorado Environmental Design
School, workshops for the community and school have been conducted to determine the final
design proposal for the park and school site. The design workshop (to be held November 13t"
from 6-8 pm at horizon School) and open to local area residents (including those living in the
Frasicr Meadows Retirement Community and The Brainford), will be focused on providing a
high quality and attractive park/school site with a well maintained and attractive lake.
ANALYSIS
The results of the pilot project were evaluated against four established goals.
Goal 1: Increase the lake surface area to approximately a water elevation of 5,315 feet.
The Department was able to meet water quality and water levels desired by the community using
multiple fills of potable water (4-6 million gallons in 2010 and 2011). The supplemental
additions exceeded the planned water budget each year. A revised water level of 5312-5314 was
achieved during the extended 2012 pilot period with minimal water additions and no additions
after July 20, 2012. The median lake surface level was 5313.60.
Goal 2: Improve the water quality of Thunderbird Lake.
Based on project monitoring and data collection, water quality at the lake has improved since
2009. The extended 2012 pilot period was able to maintain water quality with limited water fills.
Goal 3: Minimize the changes in wetland function and aquatic habitat.
The wetland mitigation area and surrounding habitat supports a transitional urban ecological
wetland and wildlife system with a higher diversity of aquatic and wetland plants being
established due to the lower water levels and increased shoreline suitable for buffer landscapes.
Goal 4: Provide opportunities for education and outreach.
The work with CU Environmental Design School, Growing Up Boulder and the Horizons K-8
charter school has focused outdoor learning opportunities for place-based experiential education
and expands the environmental education opportunities of the entire site. This will be enhanced
through a joint design process with the community and the students from the school that is
underway and will be completed with a design/build praxis studio with CU in the spring.
Use of Supplemental Water
Supplemental water added to Thunderbird Lake was measured at the source and figures were
documented during the four years of the pilot project as outlined in the table below. Water usage
to maintain the desired lake levels exceeded the water budget in each of the first three pilot study
years, and minimally exceeded the second season budget in 2012 (no water was added after July
20`).
Water Volume (gallons} added to Thunderbird Lake (2009-2011)
2009 2010 2011 2012
Total Gallons Added 1,954,380 6,504,328 4,139,330 1,297,320
Annual Water Budget 1,307,000 1,307,000 1,307,000 1,307.000
Gallons Over Budget 647,380 5,197,328 2,832,330 27,320*
Cost for Gallons Used $12,043 $66,282 $31,593 $158*
Annual water budget for the project is divided into two seasons during the year (March I - June 30 and
July 1 - Nov. 30). In 2012, second season use was slightly exceeded by 27,320 gallons resulting in an
over-use cost.
UPDATE TO BOAKDS
Water Resources Advisory Board (WRAB)
During the February 27, 2012 meeting, staff provided an update to WRAB on February 27, 2012
on the project results, whether the goals of the Adaptive Management Plan goals were met and
lessons learned. The WRAB recommended that the City Manager extend the Thunderbird Lake
Pilot project through December 31, 2012, and that the lake be maintained in a manner generally
consistent with the previously recommended "Option D - Potable Water - multiple fills per year.
The WRAB also indicated that during this period, that the City should continue to explore
options to improve the sustainability of the lake management plan, and that assessment of any
associated plant investment fees be deferred pending establishment of a long tern management
plan and water budget.
Parks and Recreation Advisory Board (PRAB)
On April 23, 2012, DRAB was provided an update on the project results, whether the goals of the
Adaptive Management Plan were met and lessons learned. At the meeting, PRAB was provided
with an overview of the project and current lake status and recommendations for next steps of
site management for Admiral Burke Park and Thunderbird Lake. The PRAB had questions on
the service level of the park site to the community and whether the continued approach was
sustainable in practice. Staff indicated that its recommendation was to extend the pilot period to
allow additional analysis of alternatives that would reduce water demands and improve long term
sustainability. The PRAB did not have a specific motion or recommendation other than a verbal
acknowledgement of the proposed management actions for 2012 and that the topic would be
revisited by Spring of 2013.
City Council
On May 29, 2012, City Council was provided an update on the project results, whether the goals
of the Adaptive Management Plan were met and lessons learned. In addition Council was
presented with the initial findings from the consultant team of Biohabitat that indicated suitable
ground water that would maintain a lower lake level (5312-5313) without the addition of potable
water fills.
FINDINGS
Based on observations and data collection, city activities have met the major water resource
goals set forth in the Adaptive Management Plan - notably improving water quality, reaching a
target elevation of, and minimizing impacts to the wetlands. The groundwater data confirmed
that the aquifer is relatively stable from year to year.
The 2012 monitoring data continue to be collected and processed. This year provided valuable
information for anticipating future conditions. Additional infonnation on lake bottom depths
collected in Spring 2012 were made using a laser level and boat so as to refine the understanding
of the lake near its center. This information revealed that previous estimates of total lake depth
Oust over 5 ft) were too shallow. The deepest part of the lake is at about 5,306 ft or roughly 8 ft
below the lake surface (i.e., 5314 ft). Wetland types and areas were also remapped in 2012 to
update previous mapping. Additionally, the groundwater and surface water collected to date were
reviewed to identify minimum elevations that have been observed. The minimum groundwater
elevations did not stay low for long periods, which may in part be due to water additions that
offset the declines. The minimum levels nevertheless provide a starting point for projecting
"worst case" extended low water levels.
All of the information gathered in 2012 was integrated into a conceptualized view of future
conditions compared to current. The findings support that the minimurn groundwater elevations
would still sustain a lake while creating shifts in vegetation around the lake. Wetland zones will
move in toward the lake center, and outer zones will shift from wetland to transition and upland
zones in response to the reduction in water availability. Restoration or adaptation planting would
help facilitate the creation of these projected zones so that opportunistic weed encroachment
could be minimized. A key to maintaining the open water area is continued City maintenance to
monitor and treat water quality and excess accumulation of aquatic vegetation. Additionally, a
long-terns adaptive management plan for the lake will help future managers understand and
respond to fluctuations, so for example in high precipitation years the outlet could be opened to
allow flushing flows to freshen the water quality.
The water level of the lake surface has maintained an average level of 5314 to 5313 for most of
the summer with no additions of water since July 20th of this year. The current reading of the
lake as of October 24th is at 5312.91 which was the second lowest level all summer, but within
the range that will maintain a lake surface equal to that achieved during this season. The
department was able to maintain the current surface this summer while not adding water after the
July time frame even though this was one of the hottest and driest on record. The department will
also be managing the wetland aquatic plants and water quality as we did this summer to maintain
clarity and view corridors into the lake from various locations. The department will strive to
improve viewing areas for residents and enhance the Admiral Burke Memorial to include an
appropriate overlook of the entire lake area.
NEXT STEPS
The department continues to work with the larger community surrounding the park, including the
Horizon School, to develop concepts that will enhance access to the lake and create outdoor
learning opportunities and interpretive areas. This could include boardwalks, overlooks and
gathering areas. Staff is conducting a joint learning session with Horizon School and the CU
School of Environmental Design students who are part of a program called "Growing Up
Boulder". This work will focus on grades 4-8 and help with the design of the new school/park
area. They will be exploring the nature of the place including water quality issues at the lake.
Please sec this link for additional information:
htW://exploi-ationsinburkepark.weebly.com/indcx.hti-nl
The Department will be continuing the work on the site planning and will be presenting the
results of this work to PRAB and City Council in the first quarter of 2013. This will include
information regarding maintenance of the lake at the current water level, without the addition of
potable water and the use of Adaptive Management Practices to control water quality, visual
quality and aquatic species to preserve the open water at or above levels maintained in 2012. In
addition the work related to the community outreach, in partnership with CU Environmental
Design School and Growing Up Boulder, that has engaged local residents and the Horizon
School, will be presented. The work is intended to help develop an acceptable desired condition
for Admiral Burke Park, including the aquatic feature. The development of a synergistic
park/school interface with a restoration component for Thunderbird Lake and the development of
the associated project costs and budget should also be completed by spring of 2013.
CITY OF BOULDER
WATER RESOURCES ADVISORY BOARD
AGENDA ITEM
MEETING DATE: November 19, 2012
AGENDA TITLE: Update on Wastewater Treatment Facility Nutrient Compliance
Study
PRESENTERS:
Jeff Arthur, Director of Public Works for Utilities
Chris Douville, Coordinator of Wastewater Treatment
Douglas Sullivan, Utilities Project Manager
EXECUTIVE SUMMARY:
The City of Boulder (city) 75th Street wastewater treatment facility (WWTF) received anew
Colorado Discharge Permit System (CDPS) discharge permit which became effective
May 1, 2011. The permit limits of highest concern are the low daily maximum ammonia limits
and new daily maximum nitrate limits. The CDPS permit includes a compliance schedule for
ammonia and nitrate, and multiple progress reports are required. The new ammonia and nitrate
limits go into effect December 1, 2017.
In June 2012, the Colorado Water Quality Control Commission (Commission) approved
technology-based nutrient effluent limits, through Regulation 85, for total inorganic nitrogen
(TIN) and total phosphorus (TP). The Commission also approved restrictive water quality
standards, through Regulation 31, for nitrogen, phosphorus, and chlorophyll u (algae). The
October 15, 2012 WRAB Agenda Item for Wastewater Treatment Facility Regulatory
Requirements can be referenced for details related to Regulation 85 and Regulation 31.
In February 2012, staff initiated a Nutrient Compliance Study (NCS) with a consultant to
evaluate options for complying with ammonia and nitrate permit limits, as well as Regulation 85
and 31 requirements in the future. The study involved five technical memorandums which have
been finalized. The final NCS report is forthcoming.
The overall goals of the NCS were to:
1. Assist the city with detennining what treatment upgrades are best suited to comply with
the upcoming regulations
Agenda VI PAGE I
2. Identify when to implement these phased treatment upgrades
3. Provide the city with planning level cost estimates
A copy of the draft NCS Report's Executive Summary is included as Attachment A.
The NCS update is being presented as an information item and fonnal action by WRAB is not
required. There are significant cost implications to meet nitrogen and phosphorus regulations
and those costs will be reflected in the annual Capital Improvement Projects (CIP) budget, which
will require WRAB approval. This update provides the technical basis for future capital
improvements and provides WRAB with an opportunity to ask questions and provide input on
WWTF compliance strategies for nitrogen and phosphorus.
BACKGROUND:
On May 1, 2011 a new751h Street WWTF CDPS discharge pennit, issued by the Colorado Water
Quality Control Division (Division), became effective. During the pennit renewal process in
2010 and 2011, city staff negotiated with the Division to include a compliance schedule in the
pen-nit to allow sufficient time to evaluate, develop strategies, and modify or build new treatment
facilities to comply with lower ammonia limits, specifically daily maximum ammonia limits, and
the daily maximum nitrate limit. The city has until December 1, 2017 to comply with these
limits.
In June 2012, the Commission approved two new regulations to control the discharge of
nutrients in Colorado. The first regulation, Regulation 85, limits the amount of total inorganic
nitrogen (TIN) and total phosphorus (TP) that can be discharged from 44 municipal W WTFs in
the State, including the city's 75th Street WWTF. Regulation 85 implements technology-based
effluent limitations for TIN and TP for all W WTFs with a flow equal to or greater than 1 million
gallons per day (mgd) and which discharge to a "priority" water. It is anticipated that
Regulation 85 requirements will be implemented into the next 75th Street WWTF CDPS
discharge permit in 2016. Regulation 31 is the second nutrient regulation approved by the
Commission in June 2012 and is intended to control the discharge of nutrients beyond
Regulation 85 requirements if Regulation 85 requirements are not sufficient to protect surface
waters. Regulation 31 will apply total nitrogen (TN), TP, and chlorophyll a (algae) water quality
standards to Boulder Creek and 75th Street W WTF effluent limits for TN and TP would be based
on these standards. The chlorophyll a standard will be applied in Boulder Creek and used as an
indicator of impainnent from the discharge of nutrients. The 75th Street WWTF is the 5th largest
WWTF in Colorado (based on flow capacity) out of 379 facilities statewide.
Agenda VI PAGE 2
A summary of upcoming nitrogen and phosphorus effluent limits is shown in Table 1.
Table 1. City of Boulder Nutrient Permit Limits
Arnnionia- Nitrate- TIN- TP-
Date TN-Nitro
Phase Nitrogen (ing/L)Nitrogen Nitrogen gen Phosphorus
Effective (mg/Q ^ Chronic Acute (MWL) 2 (mg/I-) 3 (rng/L) 5
Current May 1.2011 5.3 15.3
Existing ,
Permit Compliance Dec 1, 2017 1.9 1.9 17.9/14.7
Schedule
Regulation 85 Approx. 2022 1.91 1.91 17.9/ 14.72 15 1
Regulation 31 Approx. 2030 1.9 1.91 17.9/ 14.72 153 2.01 0.17
1. Ammonia limits vary monthly. Values listed are most restrictive monthly values for the year. Ammonia limits are assumed to continue
at the same levels under Regulation 85 and Regulation 31, but are not specifically part of those regulations.
2. Nitrate limit is a daily maximum value. The nitrate limits are assumed to continue under the Regulation 85 and Regulation 31 phases
but are not specifically part of those regulations. The value 17.9 mgN/L is for plant average month flows less than 20 mgd. The value
14.7 mgN/L is for plant average month flows greater than 20 mgd.
3. Total Inorganic Nitrogen (TIN) limit is an annual Median. The TIN limit is assumed to continue into the Regulation 31 time frame but is
not specifically part of that regulation.
4. Total Nitrogen (TN) limit is a 5-year median.
5. Total Phosphorus (TP) limit is a 5-yea r median.
75th Street WWTF Ammonia and Nitrate Compliance
The new 75th Street WWTF CDPS discharge permit has more restrictive daily maximum
ammonia effluent limits, and a new nitrate effluent limit. Neither of these limits can reliably be
met with current WWTF treatment processes and additional improvements and/or optimization
strategies are necessary. If the new daily maximum ammonia and nitrate effluent limits had been
effective during a "trial" 3 year period (September 2009 through August 2012), a total of 27
daily maximum ammonia effluent limit exceedances would have occurred and a total of 45
nitrate effluent limit violations would have occurred. This level of permit compliance is clearly
unacceptable.
Regulations 85 and 31 Compliance
The 75th Street WWTF is not able to meet the provisions of Regulation 85 based on current
performance. As the current WWTF configuration does not remove any phosphorus, the TP
limits for Regulation 85 are not achievable without facility modifications. Based on monitoring
data for the past 3 years, the average TP effluent concentration was 3.5 mg/L, significantly above
the annual median limit of 1.0 mg/L and above the 95th percentile limit of 2.5 mg/L. However,
based on monitoring data for the past 3 years, the effluent TIN concentration would meet the
Regulation 85 annual median consistently, but the 95th percentile limits would have been
exceeded for 3 of 36 months.
The provisions of Regulation 31 mandate extremely restrictive (low) effluent limits, representing
essentially effluent concentrations at or near the industry threshold of what is achievable through
current treatment technologies. Significant facility modifications will be required to comply
with Regulation 31.
Agenda VI PAGE 3
COUNCIL FILTER IMPACTS:
Economic: Non-compliance with state or federal regulations, and the exceedance of WWTF
effluent limits, can result in result in fines up to $27,000 per day, per violation, from state and
federal regulating agencies. Compliance with future WWTF effluent limits will require
additional wastewater capital improvements and long-term, ongoing operation and maintenance
costs. Compliance with Regulation 31 will have significant economic impacts.
Environmental: The exceedance of WWTF effluent limits can impact the health of Boulder
Creek aquatic life by increasing the concentration of regulated constituents above the regulatory
level set to protect aquatic life. Human health can also be impacted if permit compliance is not
obtained since Boulder Creek water downstream of the WViWTF is designated for recreation and
raw water supply. Improved water quality can enhance the aquatic community in Boulder Creek
and further protect human health.
Social: Social benefits to the community can be achieved through continued improvement in
water quality and the protection of public and environmental health, which provide improved
quality of life. A strong commitment to water quality protection compliments a safe community
as determined through year 2013 Priority Based Budgeting results.
ANALYSIS:
In 2012, the city contracted with Brown and Caldwell Engineers to complete a study (Nutrient
Compliance Study or NCS) to evaluate treatment options to comply with daily maximum
ammonia and daily maximum nitrate effluent limits in the current CDPS pen-nit, as well as future
nutrient removal requirements under Regulation 85 and Regulation 31. The study started in
February and is scheduled for completion in December.
The overarching goals of the NCS are:
• Determine what treatment upgrades are best suited to meet the increasingly demanding
nutrient removal requirements from the three regulatory actions
• Identify when to implement the phased treatment upgrades
• Provide the city with planning level cost estimates for the 6-year and 20-year CIP
• Optimize and utilize the existing facility infrastructure and systems
• Ensure that each treatment upgrade builds upon current systems and aligns with future
treatment needs
• Plan for no stranded investments (i.e. investing in a process or technology now that
would be abandoned later)
The key areas of study are:
• Optimization of the current facility
• Modifications or improvement to meet daily maximum ammonia and nitrate limits by
December 2017 (termed "current permit" requirements)
• Modifications or improvements to meet Regulation 85 TIN and TP limits by year 2022
(assuming a compliance schedule is granted)
• Modifications or improvements to meet Regulation 31 TN and TP limits by year 2030
Agenda VI PAGE 4
• Recommendations for project phasing and timing
• Probable opinions of cost for capital improvements and ongoing O&M costs
City staff worked closely with Brown and Caldwell through five (5) technical memorandums
(TMs) and three (3) team workshops to collaborate on options and alternatives. The five
technical memorandums titles are listed below and covered the following topics:
• TM 1 - Existing Facility Evaluation and Optimization Options
• TM 2 - Current Permit Compliance
• TM 3 - Regulation 85 Compliance
• TM 4 - Regulation 31 Compliance
• TM 5 - Costs and Recommendations for Project Phasing
To gain some perspective on the level of analysis and depth of evaluation during the NCS, a brief
summary presenting the highlights of TMs 1 through 4 is included as Attachment B.
A copy of finalized TM5 in included as Attachment C. This TM provides an important
summary of project phasing and associated costs to address the increasingly restrictive effluent
limits.
Summary and Conclusions
The NCS has revealed that:
• Optimization alone will not allow for continual, reliable compliance with daily maximum
ammonia and nitrate limits. However, several optimization opportunities exist that can
positively affect ammonia and nitrate performance, and these are recommended for
testing in 2013.
c Costs for optimization are considered to be minimal and will not affect the CIP
budget. Staff time will be required, and there will be some incurred expenses, but
wastewater treatment O&M budget will be utilized to fund optimization activities.
• A capital improvement project should be completed prior to December 2017 to allow the
facility to more reliably meet the daily maximum ammonia and nitrate limits. However,
there will still be an ongoing compliance risk with daily maximum limits as there is no
guaranteed treatment method.
o The recommended improvements involve a 4-stage Bardenpho process with
Supplemental Carbon facilities. A capital cost of $1,376,000 has been
estimated, with a total project cost of approximately $1.9M.
• Improvements and optimization implemented to address daily maximum ammonia and
nitrate limits will result in reliable compliance with the TIN requirements of Regulation
85, and no further modifications will be required to address the nitrogen component of
Regulation 85.
Agenda VI PAGE 5
A capital improvement project will need to be completed prior to 2022 to allow the
facility to remove phosphorus and reliably meet the TP requirements of Regulation 85.
o The recommended improvements involve chemical phosphorus removal via the
CoMag@ process (ballasted flocculation and clarification), as well as the
Ostara Pearl@ phosphorus removal/recovery process. A capital cost of
$14,723,000 has been estimated, with a total project cost of approximately
$20.3M.
• Any facility modifications implemented to address Regulation 85 will compliment the
treatment systems currently in operation at the 75`1 Street WWTF, as well as align with
futUrc processes and set the facility up for future compliance with Regulation 31.
• Another capital improvement project will need to be completed prior to 2030 to allow the
facility to remove nitrogen and phosphorus to meet the requirements of Regulation 31.
o The recommended improvements involve a moving bed biofilm reactor
(MBBR), as well as increased chemical dosing in the CoMag@ process. A
capital cost of $8,861,000 has been estimated, with a total project cost of
approximately $12.2M.
NEXT STEPS:
• Staff are working with Brown and Caldwell to complete the final report for the Nutrient
Compliance Study by the end of 2012. This final report will be made available to
WRAB.
• City staff will continue collect and analyze data with respect to treatment performance.
• By March 2013, city staff will start reporting total nitrogen and total phosphorus data to
the Colorado Water Quality Control Division as part of the Nutrient Monitoring
requirements of Regulation 85.
• In 2013, wastewater treatment staff will implement and test optimization strategies for
ammonia and nitrate.
• City staff will prepare a CIP budget for WRAB review and approval that includes
appropriate planning for facility upgrades.
• Nutrient regulatory updates will be provided to WRAB through Matters from Staff or a
formal Agenda Item at future meetings.
Agenda VI PAGE 6
ATTACHMENTS:
A: Draft Nutrient Compliance Study Report - Executive Summary
B: Technical Memorandums 1 through 4 Summary
C: Technical Memorandum No. 5 - Costs and Recommendations
Agenda VI PAGE 7
Attachment A
DRAFT
Boulder 75th Street
Wastewater Treatment Facility
Nutrient Compliance Study
Report
Prepared for
City of Boulder
Boulder 751h Street Wastewater Treatment Facility
Nutrient Compliance Study Report
Prepared for
City of Boulder, Boulder, CO
November 2, 2012
This is a draft and is not intended to be a final representation
of the work done or recommendations made by Brown and Caldwell.
It should not be relied upon; consult the final report
Limitations: This document was prepared solely for City Boulder in accordance with
professional standards at the time the services were performed and in accordance
with the contract between City Boulder and Brown and Caldwell dated November 21,
2011. This document is governed by the specific scope of work authorized by City
Boulder; it is not intended to be relied upon by any other party except for regulatory
authorities contemplated by the scope of work. We have relied on information or
instructions provided by City Boulder and other parties and, unless otherwise
expressly indicated, have made no independent investigation as to the validity,
completeness, or accuracy of such information.
Brown . Caldwellm 19
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Nutrient Compliance Study Report
Table of Contents
Executive Summary 1
Evaluation and Report Organization 2
Recommendations 2
Estimated Costs and Proposed Layouts 5
Project Approach and Schedule 6
Appendix A: TM 1 - Existing Facility Evaluation ................................................................................................A
TM 1 Appendices:
A. Testing Protocol No.1
Appendix B: TM 2 - Current Permit Compliance B
TM 2 Appendices:
A. BioWin Simulation Results
B. Proposed Layouts
C. Cost Estimates
Appendix C: TM 3 - Regulation 85 Compliance C
TM 3 Appendices:
A. BioWin Simulation Results
B. Proposed Layouts
C. Cost Estimates
Appendix D: TM 4 - Regulation 31 Compliance D
TM 4 Appendices:
A. DON Testing Protocol and Results
B. Proposed Layouts
C. Cost Estimates
Appendix E: TM 5 - Recommendations and Costs ...........................................................................................E
TM 5 Appendices:
A. Project Costs
Appendix F: Comparing the Performances of Constant Methanol Dosage and Paced Methanol Dosage F
Appendix G: Summary of Nutrient Regulations 85 and 31 G
Appendix H: Workshop/Meeting Minutes H
Appendix I: Draft Deliverable Comments/ Responses .......................................................................................I
Appendix J: Calculations J
Appendix K: BioWin Simulations - Selected Alternatives K
Brown Caldwell
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Executive Summary
On June 11, 2012 the State of Colorado implemented new environmental regulations that significantly
increased the amount of nutrient removal required for wastewater treatment facilities that discharge to
Colorado water bodies. The City of Boulder's 75th Street Wastewater Treatment Facility (WWTF)
currently discharges to Boulder Creek and consists of secondary treatment that removes ammonia
through nitrification, and nitrate through partial denitrifi cation. Phosphorus removal is not part of the
current process configuration. In March of 2012, the City hired Brown and Caldwell to assess the
impacts of the new regulations on the WWTF.
The purpose of this Nutrient Compliance Study was to review the treatment process capabilities of the
City of Boulder's 75th Street WWTF, and determine how best to meet future nutrient effluent limitations,
specifically focusing on the following three regulatory actions:
• City of Boulder 75th St. WWTF CDPS Permit No. CO-0024147 (May 2011)
• Colorado Department of Public Health and Environment (CDPHE) Regulation #85 -Nutrient
Management Control Regulation
• CDPHE Regulation #31 -The Basic Standards and Methodologies for Surface Water Regulations
The nutrient related permit limits (existing and expected future) are presented below in Figure 1.
2011 2017 2022 2031
Current CurrentPemlit Reg85 Regsl
Compliance
Permit I Schedule
y3
Ammonia,m -N/L
Nitrate,m -N/L
Total Inorganic Nitrogen,mg-N/L
Total Phosphorus, mg-P/L
Total Nitrogen,mg-N/L
Figure 1. City of Boulder Nutrient Permit Limits.
The overall goals of this Study were to:
1. Assist the City of Boulder with determining what treatment upgrades are best suited to comply
with the upcoming regulations
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Nutrient Compliance Study Report Executive Summary
2. Identify when to implement these phased treatment upgrades
3. Provide the City with planning level cost estimates.
This executive summary serves as a brief recap of the Study and highlights the overall recommended
treatment technologies, estimated costs, proposed layouts and project schedule. Additional details and
information on the alternatives evaluation and selection can be found in the accompanying appendices.
Evaluation and Report Organization
The first phase of this Study was to evaluate the existing treatment processes and determine
opportunities for optimization. The subsequent phases of the study evaluated treatment options to meet
the current, Regulation 85, and Regulation 31 permit limits shown in Table 1. A summary memo
compiled the recommendations and costs from the evaluation and presented a project schedule and
budget for implementation.
Five technical memorandums (TMs) were developed for this Study and three workshops were held with
City staff to discuss and select the recommended treatment technologies. Details on the evaluation and
selection of treatment alternatives can be found in the individual TMs.
The following is a list of the TMs that are provided in the appendices:
• TM 1- Evaluation of Existing Facility
• TM 2 - Current Permit Limit Compliance
• TM 3 - Regulation 85 Compliance
• TM 4 - Regulation 31 Compliance
• TM 5 - Recommendations and Costs
Recommendations
The following sections summarize the recommendations from each of the TMs including process
descriptions and basis for selection. A number of alternatives were evaluated for each phase of
treatment, based on the following criteria:
• Best use of the existing facilities
• Compatibility with previous and future phases
• Minimal use of external carbon sources
• Reduced compliance risk
TM1 - Existing Facility Evaluation
The first phase of this study was to evaluate opportunities to optimize the current processes at the 75th
Street WWTF in order to most effectively set the plant up to meet future permit limits. As part of this
evaluation, Brown and Caldwell compiled and evaluated plant data to conduct a plant-wide mass
balance and calibrate the BioWin model. In addition, a supplemental dissolved oxygen (DO) sampling
campaign was conducted by plant staff to understand the impacts on denitrification.
The major opportunities for improvements include optimizing nitrification and denitrification
performance, and centrate management, specifically:
• Reducing the DO in the anoxic zones to improve denitrification.
• Extending the dewatering schedule from three to five days per week to better equalize the
centrate and improve nitrification and denitrification performance.
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TM2 - Current Permit Limit Compliance
When the compliance schedule in the current permit goes into effect, the most critical issues for the
WWTF will be meeting the future requirements for daily maximum effluent ammonia concentrations and
daily maximum effluent nitrate concentrations. A number of viable treatment technologies were
considered to meet effluent permit limits including options to address peak ammonia and nitrate
excursions, and to address the carbon deficit.
Treatment Recommendation:
4-Stage Bardenpho process with methanol (MeOH) facilities (as-needed basis)
Process Description:
The 4-Stage Bardenpho process has four stages of biological treatment: anoxic, aerobic, anoxic, final
aeration. This process can be implemented within the existing aeration basins with some minor internal
structural and control modifications. Construction of a second anoxic zone will be required for each
basin. This change will require modifying the location of the IMLR pumps, addition of a chimney baffle
(for carbon addition) for each basin, new mixers, and relocation of some of the ceramic diffusers.
This alternative assumed carbon addition to the second anoxic zone of each aeration basin. Carbon can
be added to either or both anoxic zones, but this can be evaluated during design to determine the
optimum proportion.
Benefits:
• Better utilization of free influent carbon than current configuration
• In addition to meeting the maximum daily limits, also meets TIN limits under Regulation 85
• Utilizes existing aeration basins with slight modifications to the configuration
• Similar to current process operation
• Low cost
An immediate result of the analysis is ongoing investigations by City staff to evaluate potential local
waste products that could be used to reduce or eliminate the need for methanol or other chemical
products as a carbon source.
TM3 - Regulation 85 Compliance
With the annual median TIN limit addressed with the recommended 4-Stage Bardenpho process in TM2,
TM3 focused on treatment options aimed at meeting the Regulation 85 TP limit. Evaluated treatment
technologies included chemical phosphorus removal, biological phosphorus removal, and phosphorus
recovery alternatives.
Treatment Recommendation:
CoMagO for chemical phosphorus treatment and Ostara PearlO system for phosphorus recovery.
Process Description:
The CoMagO process is an iron ore (magnetite) ballasted coagulation and flocculation process. The
flocs are rapidly settled in the clarification system due the magnetite addition. The CoMagO process
consists of mixing tanks (with chemical addition), clarifier, and a magnetic drum for recovery of the
magnetite. The chemical sludge from the process can be further treated in the DAFTs or returned to the
Headworks. The CoMagO facility would be located downstream of the secondary clarifiers, prior to
disinfection.
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The Ostara Pearl@ system transforms the ammonia and phosphorous in the centrate stream into a
beneficial commercial-grade fertilizer product. This system can be installed in the existing Dewatering
Building.
Benefits:
• CoMag®
o Can be utilized in future phase to address Regulation 31 limits
o Provides added benefit of effluent TSS removal
o Compact system
o Does not inhibit the biological process
• Ostara Pearl@
o Reduces struvite precipitation potential of the centrate stream
o Reduces amount of phosphorus load to the secondary process - resulting in a reduction
of chemicals needed for chemical phosphorus removal in the CoMag® process
o Provides a revenue source from the sale of the recovered product
TM 4 - Regulation 31 Compliance
To meet the Regulation 31 limits, the 4-Stage Bardenpho process would be utilized to achieve the lowest
secondary effluent concentrations of both nitrogen and phosphorus without chemical addition. The
reasons are as follows: 1) to meet the limits expected for Regulation 31, additional nitrogen and
phosphorus removal will be required after secondary treatment; 2) utilization of carbon and coagulant
for nitrogen and phosphorus removal, respectively, will be more efficient if carried out in dedicated post-
denitrification and post-precipitation facilities.
Treatment Recommendation:
Moving Bed Biofilm Reactor (MBBR) with increased chemisral dosages for the CoMag® process.
Process Description:
Post-denitrification MBBR will be implemented in new reactors located downstream of the secondary
clarifiers. Methanol addition is required for this process. Media is used in the denitrification reactors to
grow the denitrifying bacteria and helps reduce the overall reactor volume. Following the MBBR is a
post-aeration basin to increase the DO and consume any residual methanol. This process is then
followed by the CoMag@ process to remove phosphorus, DON and suspended solids created during the
MBBR process. The exact same design and size of the CoMag® process to meet the Regulation 85 limits
can be utilized for Regulation 31. Additional alum and sodium hydroxide are needed to meet the lower
effluentTP limit.
Benefits:
• MBBR
o No filter or media blinding issues
o Smaller footprint compared to denitrification filters
o Results from US installations show effluent nitrate-nitrogen values less than 1 mg/L
• CoMag®
o System already in place for Regulation 85
o Reduces both total phosphorus and DON
BrownANDCal.dwett ES-4
DRAFT for rcvio purposes only. Use of contents on this sheet is subject to the limitations specified at tho end of this document
NCS Draft Report_11 2.7 ^ ducx
Nutrient Compliance Study Report Executive Summary
Estimated Costs and Proposed Layouts
An important part of the Study was to help the City project future budgets required for the recommended
treatment technologies. A summary of the estimated costs for each of the recommended alternatives is
provided below in Table 2.
Total 20-Year Total Cost
Annual Salvage (Capital +
Recommended Alternative Total Chemical Power I Other2 Operating Present Cost4 0&M PW -
Worth3 Salvage)
4-Stage Bardenpho
with Methanol Facility $1,376,000 1 $44,000 $22,600 $8,300 $74,900 $1,110,000 $534,600 $1,951,000
CoMag® with
CoMa Pearl@ with $14,723,000 $663,000 $7,800 $92,700 $763,500 $11,360,000 $3,270,000 $22,813,000
Ostara
MBBR 58,861000 $599,000 $104,900 $58,500 $762,400 1 $11,340,000 $11810,000 $18,391000
1. Includes power costs which assume $0.07/kWh.
2. Other 0&M costs were taken as 1% of capital for routine maintenance and parts replacement for mechanical and electrical equipment
3. Assumes inflation = 4% and interest =7%.
4. Salvage value was assumed to be 0% for mechanical- and electrical-related equipment after 20 years, and 60% for non-mechanical
equipment after 20 years.
The recommended treatment technologies to meet the current and future permit limits are shown on
Figure 2. The proposed locations on the facility site are sized based on preliminary design information
noted in the respective TMs. The processes and facilities are color-coded based on when the project is
scheduled to be implemented: red for current permit limits, green for Regulation 85, and yellow for
Regulation 31.
h
4if
i
~i, d'. `
Ail" 101
G - sE 1: L ti t li'
r:
Mild'
- - - - -may,
Figure 2. Proposed Layout for Future Processes.
Brown AND Caldwell ES-5
DRAFT for review purposes only Use of contents on this sheet is subject to the limitations specified at the end of this document
NCS Draft Report_91.2.12.docx
Nutrient Compliance Study Report Executive Summary
Project Approach and Schedule
The results of the evaluation identify three distinct projects or phases. These projects are identified
below in Table 3.
Table 2. Recommended Projects
Project l Regulation Compliance' Target/Goal Description
Current Permit Limits Daily NIi3-N < 1.9 mg/L
1 Daily N03-N < 14.7 mg/L 4-Stage Bardenpho with methanol facilities
Regulation 85 TIN Limits TIN-N < 15 mg/L
2 Regulation 85 TP Limits TP-P < 1.0 mg/L CoMag® with Ostara Pead(&
3 Regulation 31 Limits TN-N < 2.01mg/L MBBR with increased chemical dosage for CoMagO
TP-P < 0.17 mg/L
Based on the estimated project capital costs, a schedule of design and construction activities along with
the associated costs were determined. The timing and costs of these project activities are presented
below in Table 4.
TOW. Compliance Schedule and Project Costs
Treatment Technology Time Period Activities 2 Total Cost i
Project 1: 4-Stage Bardenpho 2013 Optimization $ 0
with Methanol Pre-Design and Final Design For Current
2014 Limits $ 206,400
Li
Capital Cost: $1,376,000 2015 Construction $ 1,651,200
Total Project Cost: $1,898,880 -
2016 I Startup/Testing For Current Limits $ 41,280
2017 Regulation 85 Related Pilot Testing $ 0
Project 2: CoMag® with Ostara 2018 Pre-Design For Regulation 85 $ 736,150
Pearl® 2019 Final Design For Regulation 85 $ 1,472,800
Capital Cost: $14,723,000 _ 2020 Construction $ 8,833,800
Total Project Cost: $20,317,740 2021 Construction _ $ 8,833,800
2022 Startup/Testing For Regulation 85 $ 441,690
Project 3: MBBR and CoMag® _ 2026 Regulation 31 Related Pilot Testing $ 0
w/ Increased Chemical Dosage 2027 Pre-Design For Regulation 31 $ 443,050
Capital Cost: $8,861,000 2028 _ Final Design For Regulation 31 $ 886,100
Total Project Cost: $12,228,180 2029 Construction $ 5,316,600
2030 Construction $ 5,316,600
2031 Startup/Testing For Regulation 31 $ 265,830
1. Pre-Design = 5% of capital cost. Final Design =10% of capital cost. Construction cost includes capital cost + 5% for administrative and
legal fees + 15% for construction management. Startup/Testing = 3% of capital cost.
2. For Projects 2 and 3, construction costs occurred were based on 24 months and the total capital cost was spread over two years.
As a result of this Study, the City of Boulder and the Brown and Caldwell team have selected the best
treatment alternatives to meet the current and future permits limits. These treatment alternatives
optimize and utilize the existing facility, each treatment technology builds upon and compliments the
future technologies, and there are no stranded investments. The team has also established a phased
schedule to implement these three projects, and the related cost estimates will help to establish the
City's upcoming Capital Improvements Plan to maintain compliance for the next 20 years.
Brown
ES-6
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NCS Draft Report-11 2 12.doex
This page intentionally left blank.
Attachment B
TM 1 - Existing Facility Evaluation and Optimization Options
The major issues and recommendations identified as part of this TM were grouped by
nitrification performance, denitrification performance, and centrate management.
• Nitrification-
o The plant should generally continue with current operational procedures.
o It is important to rigorously maintain the target solids retention time (SRT). If solids
are lost from the system via secondary effluent or other means, then mixed liquor
wasting should be adjusted accordingly.
o Low SVIs have occurred at other times in the past and the provision of polymer with
or without a weighting agent was discussed at those times. Polymer laboratory and
field trials could be relatively straightforward to conduct. By installing a pennanent
dosing facility, polymer could be rapidly deployed in the future when required; for
example, when bulking occurs and SVIs are inordinately high or when SVIs are low
and solids dispersal occurs.
• Denitrification-
o Increase the effective carbon and anoxic residence time by reducing the mixing
intensity in the anoxic zones. The mixing intensity could be reduced by changing the
impeller, operating the mixer in an on/off mode, or a combination of both of these
options. Some fermentation of mixed liquor would occur and the anoxic SRT would
increase. This could eventually be conducted in a field trial. BioWin simulations will
be used, although this type of activated sludge fermentation is not well predicted by
BioWin.
o Investigate primary sludge fermentation to increase the carbon feeding the anoxic
zone.
o Investigate sources of supplemental carbon, either in the form of chemical addition or
local waste stream sources.
o Optimize centrate management to reduce the peak nitrogen concentrations fed to the
biological reactors and reduce the maximum day nitrates that need to be denitrified.
o Evaluate physical modifications to the final aerated zones to reduce the internal
mixed liquor recycle (IMLR) DO concentration.
• Centrate Management-
o Extend the dewatering schedule to five days per week to reduce the volume required
for equalization under current conditions and provide a more homogenous mixture of
the centrate and scrubber water that is recycled to the secondary process.
Equalization of the centrate will benefit both nitrification and denitrification, and can
aid in reducing the maximum day effluent nitrate concentrations.
The above recommendations were selected not only to optimize current operations, but also to
provide added benefit when implemented with the recommended alternatives to meet the future
permit limits for Regulation 85 and 31.
Agenda VI PAGE 9
TM 2 - Current Permit Compliance
The NCS team considered a number of viable treatment technologies to meet the current daily
maximum permit limits for ammonia and nitrate.' The advantages and disadvantages of these
technologies were evaluated and those found best suited to meet the current limits, taking into
account both the existing configuration of the WWTF and the future effluent limits, were
selected. The treatment technologies were grouped into subsections and included:
• Options to Meet Effluent Pen-nit Limits - the options specifically address nitrate removal and
focus on denitrification.
• Options to Address Peak Excursions - these options specifically address the ammonia and
nitrate peaks related to the return centrate stream. These options could be coupled with the
above option to reduce the compliance risk associated with peak excursions.
• Options to Address Carbon Deficit - these options are specific to providing supplemental
carbon if required for the selected treatment alternatives.
The most suitable alternatives to meet the current permit are listed below in Table 2 along with
the advantages and disadvantages of each. Important benefits and disadvantages are highlighted
in green or red, respectively.
Table2. Current Permit Limit Selected Treatment Alternatives
Options to Meet Effluent Permit Lirrtits
Description 1 Pros Cons
• Same operational process • Supplemental carbon facilities required
Existing MILE process • Utilize existing basins • Continued OW (chemical addition
• Less expensive capital costs cost)
• New operational practice
• Significant energy savings • Additional controls required
Simultaneous Nitrification- . Utilize existing basins Passible i At',leabilDenitrification (SND) g mpac' on se it
• Reduce carbon deficit • Careful balance of
nitrification/denitrification required
4-Stage Bardenpho with • Utilizes existing basins • Requires minor aeration basin
Carbon to Second Anoxic Setter utilizes free influent carbon modifications, such as construction of a
Zone than current configuration new chimney baffle in each basin
• New Infrastructure and large footprint
• Additional effluent TSS removal with • Requires methanol
Post-DenitrificationMBBR DAFTs • New process operati on
• Expandableto meet Reg 31 . High cost compared to other
alternatives
0 ptio ns to Address Peak Excursions
Description I Pros Cons
• Requires equalizati on of the centrate
• Reduces carbon deficit stream
Nitritation-Anammoz Reduces nitrogen load to aeration • New operational practice
Centrate Treatment (e.g. basins • Additional controls
DEMON) • Reduced power •
New infrastructure
• High cost
Primary Effluent Off-Spec • No additional treatment or processes • Cannot equalize entire influent
Stream Equalization (PESTS) required ammonia load
• Reduces effluent peaks • Additional controls/ programming/
Agenda VI PAGE 10
Tabk2. Current Permit Umit Selected
TwatmentAitematives
• Utilize existing PESTS monitoring
Options to Address Carbon Deficit
Description Pros Cons
• Partial reduction of supplemental • Reduces digester gas production
carbon deficit • Standby carbon addition recommended
O Fermented Primary Lowest life-cycle cost compared with • Odor control required
Sludge)
purchased methanol, forthe same • High capital cost compared to chemical
mass of nitrogen removal facilities
• Fluctuating costs
Purchase Carbon Good consistency of product • General safety concerns
• Potential flammability
Based on the evaluation and alternative cost comparison, the 4-Stage Bardenpho process is the
recommended treatment process to meet the current permit limits. It is also recommended that
methanol facilities are constructed as part of this upgrade for operation on an as-needed basis.
It is important to note that the city is currently investigating a brewery waste source that could
potentially provide carbon in lieu of (or in addition to) methanol. In addition, the city is also
considering Micro-C as a back-up source of supplemental carbon. The additional storage and
feeding requirements for these alternative carbon sources should be considered and evaluated
further during preliminary design.
Understanding that additional investigation may alter the final design, for the purpose of
determining costs, treatment layouts, and schedules, the 4-Stage Bardenpho process with 75 gpd
methanol addition was the selected alternative to meet the current permit limits. While meeting
these daily ammonia and nitrate limits, the annual median TIN limit is also met. This alternative
was carried forward in the evaluation of phosphorus removal and TIN compliance alternatives
for Regulation 85.
TM 3 - Regulation 85 Compliance
With the annual median TIN limit addressed with the recommended 4-Stage Bardenpho process
in TM2, TM3 focused on treatment options aimed at meeting the Regulation 85 TP-P
requirement of 1 mg/L as a 12-month moving median value. The evaluated treatment options
were grouped into the following categories:
• Biological Phosphorus Removal Options
• Chemical Phosphorus Removal Options
• Phosphorus Removal and Recovery Options
The most suitable alternatives to meet Regulation 85 are listed below in Table 3 along with the
advantages and disadvantages of each. Important benefits and disadvantages are highlighted in
green or red, respectively.
Agenda VI PAGE 11
Table 3. Regulation 85 Selected Treatment Alternatives
Biological Phosphorus Removal Options
Description I Pros Cons
. Influentcarbon Is insufficient for nitrogen removal,
therefore definitely insufficient for appreciable P
removal
• Potentially uses influent carbon for bio-P • Chemicals are required to supplement
4~ Basin Bio P • Original design intent denitrification and P removal
Additional ammonia release impacts peak day
effluent ammonia
• Increased potential to develop struvite
Chemical Phosphorus Removal Options
Description Pros Cons
• No major treatment changes • Addition of precipitating chemicals upstream or
• Lowcapitalcost within biological treatment sequesters soluble
P04-P which inhibits the nitrifiets. There would be a
Secondary Clarification real danger of violating the peak effluent ammonia
requirement.
• Increased solids loading requiring a 5th clarifier
• EffluentTP is related to the effluentTSS
• Proven to achieve <0.05 mg/Lwithout • Requires additional unit process downstream of the
filtration. Therefore easily achieves < 1 mg/L secondary clarifiers
• Highly effective effluentTSS polishing • Additional chemical (magnetite) handling required
Post Precipitation with • Metals removal
CoMag . The degree of P removal can be directly
"dialed-in" by adjustingthe alum dosage
• Compact system
• Does not Inhibit the biological process
Phosphorus Removal and Recovery Options
Description Pros Cons
• Ostara Pearl®, • Provides the potential for revenue with sale • Additional unit process
• Multiform Harvest of the recovered product • With out blo-P operation the process maybe less
• Crystalactor • Reducesthe mass of P that needsto be than optimal
removed in the liquid stream process;
reduces alum and alkalinity dosages
• Reduce struvite precipitation potential
Based on the evaluation and alternative cost comparison, the 4-Stage Bardenpho (recommended
in TM2) with CoMag® and Ostara Pearls is the recommended treatment alternative to meet the
Regulation 85 permit limits. These costs (for the addition of CoMag® and Ostara Pearls) will
be carried forward for the overall project schedule. The city is also interested in chemical
addition in the secondary clarifiers since it was the lowest-cost option. It is recommended that
the city staff test this option first as a proof of concept to understand the downstream treatment
impacts.
TM 4 - Regulation 31 Compliance
To meet the Regulation 31 limits, the 4-Stage Bardenpho process would be utilized to achieve
the lowest secondary effluent concentrations of both nitrogen and phosphorus without chemical
addition. The reasons are as follows: 1) to meet the limits expected for Regulation 31, additional
nitrogen and phosphorus removal will be required after secondary treatment; 2) utilization of
Agenda VI PAGE 12
carbon and coagulant for nitrogen and phosphorus removal, respectively, will be more efficient if
carried out in dedicated post-denitrification and post-precipitation facilities. The evaluated
treatment options were grouped into the following categories:
• Post-Denitrification Options
• Dissolved Organic Nitrogen (DON) Removal Options
• Phosphorus Removal Options
The most suitable alternatives to meet Regulation 31 permit limits are listed below in Table 4
along with the advantages and disadvantages of each. Important benefits and disadvantages are
highlighted in green or red, respectively.
Table4. Regulation 31 Selected Treatment Alternatives
Post-Denitrification Options
Description Pros Cons
• Wealth of priorexperiencewith Denite®filters in the Low filtration rates require relatively large land
Deep Bed Denitrification U.S. for post-denitrificatlon. area.
Filters • Provide tertiary filtration and reduce secondary • Limited solids handling capacity underupset
effluentTSS and P. conditions in secondary treatment.
• Denitrification MBBR plants visited with System requires sieves and mechanical mixers
Littleton/Englewood personnel in Germany and to prevent media migration.
Scandinavia for possible implementation at the • No retention of TSS in this system (not a
plant. Manyyears of successful operation atthese disadvantage in this case).
plants.
• Operating plants in the U.S. meeting less than i
MBBR mg/L NOx•N.
• Low profile suspended media system with simpler
civil construction.
• No flteror media blinding issues. Reduced impact
of suspended solids carryoverfrom secondary
treatment.
DON Removal Options
Description Pros Cons
Enhanced Coagulation Process can be incorporated with chemical P • Removal is limited.
removal. • Not determined as yet, but removals could vary
• Least complex and lowest cost option. seasonally.
• pH conditions for DON "precipitation" and • Further ongoing laboratory testing is
adsorption correspond with requirements for P recommended.
removal. • Large amount of chemical sludge maybe
• Pilot testing is not essential. produced-more than produced for P removal.
Microfiltration (MF) or Probably the best removal of the options. • Known to be the most expensive option.
Ultrafiltration (UF) plus • No sludge generation. • High energy requirements.
Reverse Osmosis (RO) . Treatment is compact. • A large reject stream (probably 20% of the
• No upstream P removal required (RO will accomplish total flowto the membranes) must be
both DON and P removal. It will also accomplish disposed of.
some NH3-N and NOx-N removal, so the RO may • Treating or processingthe reject stream could
eliminate more than one of the post secondary be as big a challenge as removing the DON.
processes. • If the reject stream is recycled back to the
headworks, the overall treatment flow through
the plant would increase by 20%. The
membrane system would also be 20% larger
Agenda VI PAGE 13
: i a i i 31 Selected Treatment Altematim
than the influent flow.
• It is essential to pilot this process to determine
the best membrane and to determine the
actual DON, P and NOx-N removals.
Phosphorus Removal Options
Description Pros Cons
• High specific gravity of magnetite ballast provides * Requires materials handling for magnetite
high stability of the process under peak flows and addition and magnetite recovery equipment
solidsloads. • High performance of Maynard WWTP required
• Proven process demonstrates very low P and consultant (Brown and Caldwell) intervention
turbidity without filtration. In design of the clarifiers (rectangular
CoMag® • Proven process handles very high peak flow and designed instead of vendor's circular design).
solids load ratios, with minimal impacts to effluent
quality.
• High shear mixer for magnetite recovery does not
require pre-screening.
• Lowest area requirement of the alternatives.
Based on the evaluation and alternative cost comparison, the recommended alternative for
meeting Regulation 31 limits is utilizing the 4-Stage Bardenpho (recommended in TM2) and
CoMag® system (recommend in TM3) with the Moving Bed Biofilm Reactor (MBBR)
technology. The CoMag® system (installed in the previous phase) also provides a good option
for DON removal along with TP removal. The system is a good investment for the future as it
can continue to be used to meet Regulation 31 TP limits. The size of the CoMag® system does
not need to be increased from Regulation 85 requirements but additional chemicals (e.g., alum,
sodium hydroxide) will be required to meet the Regulation 31 limits.
Agenda VI PAGE 14
Attachment C
BrownAND
Caidwett Final Technical Memorandum
1697 Cole Boulevard, Suite 200
Golden, Colorado 80401
Tel: 303-239-5400
Fax: 303-239-5454
Prepared for: City of Boulder
Project Title: 75th Street Wastewater Treatment Facility Improvements
Nutrient Compliance Study
Project No: 142503-100
Technical Memorandum No.5
Subject: Costs and Recommendations
Date: October 12, 2012
To: Douglas Sullivan
From: Mark Richards, Brown and Caldwell
Copy to: Sean O'Connell, Brown and Caldwell
Prepared by: John Bratby, Stephanie Fevig
Reviewed by: Jose Jimenez, Mark Richards
Limitations:
This document was prepared safety for City of Boulder in accordance with professional standards at the time the services were performed and in
accordance with the contract between City of Boulder and Brown and Caldwell dated November 21, 2011. This document is governed by the specific
scope of work authorized by City of aoulder; it is not intended to be relied upon by any other party except for regulatory authorities contemplated by
the scope of work. We have relied on information or instructions provided by City of Boulder and other parties and, unless otherwise expressly
indicated, have made no independent investigation as to the validity, completeness, or accuracy of such information.
Costs and Recommendations
Table of Contents
List of Figures iii
iii
List of Tables "
List of Acronyms ........................................................................................................................................................iv
1. Introduction ...........................................................................................................................................................1
1.1 Summary of TM1 - Facility Optimization Options ....................................................................................2
1.2 Summary of TM2 - Current Permit Limit Compliance .............................................................................3
1.3 Summary of TM3 - Regulation 85 Compliance .......................................................................................5
1.4 Summary of TM4 - Regulation 31 Compliance .......................................................................................7
2. Recommendations and Project Approach ..........................................................................................................9
2.1 Site Layout ..................................................................................................................................................9
3. Project Costs and Schedule ...............................................................................................................................10
4. Recommendations for Bench and Pilot Scale Tests ........................................................................................10
5. Summa .....................................................................................................12
Attachment A: Project Costs .....................................................................................................................................A
BrownANDCaldwelt
i
TN15 Recommendations and Costs Finab10 12-12 docx
Costs and Recommendations
List of Figures
Figure 1. Site Plan with Recommended Treatment Technologies ........................................................................9
List of Tables
Table 1. City of Boulder Nutrient Permit Limits ......................................................................................................1
Table 2. Current Permit Limit Selected Treatment Alternatives ...........................................................................3
Table 3. Estimated Costs for 4-Stage Bardenpho with Methanol Facility ............................................................4
Table 4. Regulation 85 Selected Treatment Alternatives ......................................................................................5
Table 5. Estimated Costs for 4-Stage Bardenpho + CoMag® + Ostara Pearl@ ..................................................6
Table 6. Regulation 31 Selected Treatment Alternatives .....................................................................................7
Table 7. Estimated Costs for MBBR and CoMag® with Increased Chemical Addition ........................................8
Table 8. Recommended Projects ............................................................................................................................9
Table 9. Compliance Schedule and Project Costs ...............................................................................................10
BrownAwCaldwell
T.A4 -Ftccommendations and costs-Finel-70-12-l9Jncx
Costs and Recommendations
List of Acronyms
Bio-P Biological Phosphorus Removal PEST Primary Effluent Storage Tank
CDPHE Colorado Department of Environmental RO Reverse Osmosis
Health and Environment
SND Simultaneous Nitrification Dentrification
CDPS Colorado Discharge Permit System
SRT Solids Retention Time
DAFT Dissolved Air Flotation Thickening
SVI Sludge Volume Index
DEMON De-ammonification Process TIN Total Inorganic Nitrogen
DO Dissolved Oxygen TM Technical Memorandum
DON Dissolved Organic Nitrogen TN Total Nitrogen
IMLR Internal Mixed Liquor Recycle TP Total Phosphorus
MF Microfiltration TSS Total Suspended Solids
MBBR Moving Bed Biofilm Reactor OF Ultrafiltration
MILE Modified Ludzack-Ettinger Process
UV Ultraviolet
0&M Operation and Maintenance WWTP Wastewater Treatment Plant
OWASA Orange Water and Sewer Authority (North
Carolina) Process WWTF Wastewater Treatment Facility
o , Cadkdhweala
iV
M15-Recommendations and Costs-Final-10-12-12 docx
Costs and Recommendations
1. Introduction
The purpose of this study is to review the treatment process capabilities of the City of Boulder's 75th Street
Wastewater Treatment Facility (WWTF), and determine how best to meet future nutrient effluent limitations,
specifically focusing on the following three regulatory actions:
• City of Boulder 75th St. WWTF CDPS Permit No. CO-0024147 (May 2011)
• Colorado Department of Public Health and Environment (CDPHE) Regulation #85 -Nutrient
Management Control Regulation
• CDPHE Regulation #31 -The Basic Standards and Methodologies for Surface Water Regulations
A key part of this study is to help the City of Boulder determine what treatment upgrades are best suited to
meet the increasingly demanding nutrient removal requirements from the three regulatory actions, when to
implement these phased treatment upgrades, and to provide the City with planning level cost estimates.
The first phase of this study was to evaluate the existing treatment processes and determine opportunities
for optimization. The following phases of the study evaluated treatment options to meet current permit
limits, Regulation 85, and Regulation 31. This final phase compiles the recommendation and costs from the
evaluation and presents a project schedule and budget for implementation.
The first Technical Memorandum (TM1) presented options to optimize the current process configuration.
TM2 presented treatment alternatives to meet the current permit limits for daily maximum ammonia and
nitrate values. TM2 also addressed meeting the annual median total inorganic nitrogen (TIN) permit limit
requirement of Regulation 85. Alternatives to address the annual median phosphorus limit proposed under
Regulation 85 were discussed in TM3. TM4 presented alternatives to meet the Regulation 31 five-year
median stream values for total nitrogen (TN) and total phosphorus (TP). This final TM5 summarizes the
overall recommendations, costs, and proposed schedule for meeting the current and future effluent limits.
All nutrient related permit limits (existing and expected future) are presented in Table 1.
Table 1: tiWet Boulder NutrIent Permit 11111611-5
Ammonia-Nitrogen
Phase Date Effective mg/L)1 Nitrate-Nitrogen TIN-Nitrogen TN-Nitrogen TP-Phosphorus
Chronic Acute (mg/L) 2 (mg/L) 3 (mg/L) a (mg/L) s
Current 'May 1, 2011 5.3 15.3
Existing - - - -
Permit Compliance Dec 1, 2017 1.9 1.9 17.9/14.72
Schedule
Regulation 85 Approx. 2022 1.9 1.9 17.9 /14.72 15 I 1
Regulation 31 Approx. 2030 1.9 1.9 17.9 /14.72 153 r 2.01 0.17
1. Ammonia limits vary monthly. Values fisted are most restrictive monthly values for the year. Ammonia limits are assumed to continue at the
same levels under Regulation 85 and Regulation 31, but are not specifically part of those regulations. The actual values may vary slightly.
2. Nitrate limit is a daily maximum value. The nitrate limits are assumed to continue under the Regulation 85 and Regulation 31 phases but are
not specifically part of those regulations. The value 17.9 mg1L as nitrate-N is for plant average month flows less than 20 mgd. The value 14.7
mg/L as nitrate-N is for plant average month flows greater than 20 mgd.
3. Total Inorganic Nitrogen (TIN-N) limit is an annual median. The TIN limit is assumed to continue into the Regulation 31 time frame but is not
specifically part of that regulation.
4. Total Nitrogen (TN-N) limit is a 5 -year median
5. Total Phosphorus (TP-P) limit is an annual median under Regulation 85 and a 5 -year median under Regulation 31.
' ' 1
Costs and Recommendations
When Regulation 85 limits come into effect, the WWTF will still have to comply with the daily maximum
ammonia and nitrate limits. When Regulation 31 limits come into effect, the WWTF will still have to comply
with the daily maximum limits in addition to the Regulation 85 annual median TIN limit.
1.1 Summary of TM1 - Facility Optimization Options
The first phase of this study was to evaluate opportunities to optimize the current processes at the 75th
Street WWTF. As part of this evaluation, Brown and Caldwell compiled and evaluated plant data to conduct
a plant-wide mass balance and calibrate the BioWin model. In addition, a supplemental sampling campaign
was conducted by plant operations and laboratory personnel to evaluate the characteristics of the secondary
influent and specifically determine the impacts of the dissolved oxygen (DO) entering the anoxic zones.
The major issues and recommendations identified as part of this phase were grouped by nitrification
performance, denitrification performance, and centrate management. More details on these issues can be
found in TM1. The overall recommendations from this evaluation include:
• Nitrification
o The plant should generally continue with current operational procedures.
o It is important to rigorously maintain the target solids retention time (SRT). If solids are lost
from the system via secondary effluent or other means, then mixed liquor wasting should be
adjusted accordingly.
o Low SVIs have occurred at other times in the past and the provision of polymer with or without
a weighting agent was discussed at those times. Polymer laboratory and field trials could be
relatively straightforward to conduct. By installing a permanent dosing facility, polymer could be
rapidly deployed in the future when required; for example, when bulking occurs and SVIs are
inordinately high or when SVIs are low and solids dispersal occurs.
• Denitrification
o Increase the effective carbon and anoxic residence time by reducing the mixing intensity in the
anoxic zones. The mixing intensity could be reduced by changing the impeller, operating the
mixer in an on/off mode, or a combination of both of these options. Some fermentation of
mixed liquor would occur and the anoxic SRT would increase. This could eventually be
conducted in a field trial. BioWin simulations will be used, although this type of activated
sludge fermentation is not well predicted by BioWin.
o Investigate primary sludge fermentation to increase the carbon feeding the anoxic zone.
o Investigate sources of supplemental carbon, either in the form of chemical addition or local
waste stream sources.
o Optimize centrate management to reduce the peak nitrogen concentrations fed to the
biological reactors and reduce the maximum day nitrates that need to be denitrified.
o Evaluate physical modifications to the final aerated zones to reduce the internal mixed liquor
recycle (IMLR) DO concentration.
• Centrate Management
o Extend the dewatering schedule to five days per week to reduce the volume required for
equalization under current conditions and provide a more homogenous mixture of the centrate
and scrubber water that is recycled to the secondary process. Equalization of the centrate will
benefit both nitrification and denitrification, and can aid in reducing the maximum day effluent
nitrate concentrations.
Brown.ND Caldwell 2
iM5-Reonmmendadons and Costs-Final-10-12-12 docx
Costs and Recommendations
The above recommendations were selected not only to optimize current operations, but also to provide
added benefit when implemented with the recommended alternatives to meet the future permit limits
described in the following sections.
1.2 Summary of TM2 - Current Permit Limit Compliance
When the compliance schedule in the current permit goes into effect, the most critical issues for the WWTF
will be meeting the future requirements for daily maximum effluent ammonia concentrations (down to 1.9
mg/L NH3-N in summer, and 2.8 mg/L NH3-N in winter), and daily maximum effluent nitrate concentrations
(17.9 mg/L N03-N for month average flows less than 20 mgd, and 14.7 mg/L N03-N for month average
flows greater than 20 mgd).
Brown and Caldwell considered a number of viable treatment technologies to meet the current daily
maximum permit limits for ammonia and nitrate. The advantages and disadvantages of these technologies
were evaluated and those found best suited to meet the current limits, taking into account both the existing
configuration of the WWTF and the future effluent limits, were selected. The treatment technologies were
grouped into subsections and included:
• Options to Meet Effluent Permit Limits - the options specifically address nitrate removal and focus
on den itrifi cation.
• Options to Address Peak Excursions - these options specifically address the ammonia and nitrate
peaks related to the return centrate stream. These options could be coupled with the above option
to reduce the compliance risk associated with peak excursions.
• Options to Address Carbon Deficit - these options are specific to providing supplemental carbon if
required for the selected treatment alternatives.
The most suitable alternatives to meet the current permit are listed below in Table 2 along with the
advantages and disadvantages of each. Important benefits and disadvantages are highlighted in green or
red, respectively.
Table 2. Current Permit Limit Selected Treatment Alternatives
Options to Meet Effluent Permit Limits
Description Pros cons
• Same operational process • Supplemental carbon facilities required
Existing MLE process • Utilize existing basins • Continued 0&M (chemical addition cost)
• Less expensive capital costs
• New operational practice
• Significant energy savings • Additional controls required
Simultaneous Nitrification- e Utilize existing basins Possibleimpactonsettieability
Denitriftcatlon (SND) • Reduce carbon deficit Careful balance of
nitrification/denitrification required
4-Stage Bardenpho with • Utilizes existing basins • Requires minor aeration basin
Carbon to Second Anoxic Zone • Better utilizes free influent carbon than modifications, such as construction ofa
current configuration new chimneybaffle in each basin
• Additional effluent7SS removal with • New infrastructure and large footprint
Post-Denitrificabon MBBR DAFrs • Requires methanol
• Expandable to meet Reg 31 • New process operation
• High cost compared to other alternatives
Brown ANDCalidweV 3
TM5 Recommendations and Costs-Final 10 12-12 docx
Costs and Recommendations
Table 2. Current Permit Limit Selected Treatment Alternatives
Options to Address Peak Excursions
Description Pros Cons
• Requires equalization of the centrate
• Reduces carbon deficit stream
Nitritation-Anammox Centrate . Reduces nitrogen load to aeration basins • New operational practice
Treatment (e.g. DEMON) • Additional controls
• Reduced power . New Infrastructure
• High cost
• No additional treatment or processes • Cannot equalize entire influentammonia
Primary Effluent Off-Spec required load
Stream Equalization (PESTS) • Reduces effluent peaks • Additional controls/ programming/
• Utilize existing PESTS monitoring
Options to Address Carbon Deficit
Description Pros Cons
• Partial reduction of supplemental carbon Reduces digester gas production
OWASA (Fermented Primary deficit . Standby carbon addition recommended
Sludge) • Lowest life-cycle cost compared with • Odorcontrol required
purchased methanol, forthe same mass of High capital cost compared to chemical
nitrogen removal facilities
• Fluctuating costs
Purchase Carbon . Good consistency of product • General safety concerns
• Potential flammability
Based on the evaluation and alternative cost comparison, the 4-Stage Bardenpho process is the
recommended treatment process to meet the current permit limits. It is also recommended that methanol
facilities are constructed as part of this upgrade for operation on an as-needed basis. Details on the
evaluation, layouts, and cost estimates are provided in TM2. Table 3 presents the estimated costs for the
recommended alternative.
Table3. Estimated Costs for
Capital Cost Annual 0&M Costs Total 20-Year Total Cost
Annual Salvage (Capital +
4-Stage Methanol Total I Chemical;' Power2 Other2 Operating i Wort h3 Cost2 0&MPW-
Bardenpho Facility Cost Salvage)
$665,973 $709,743 $1,376,000 $44,000 1$22,600 $8,300 $74,900 $1,110,000I $534,600 $1,951,000
1. Methanol cost is based on current price of $1.591gallon. Provided by litttetonl ngtewood WWTP staff.
2. Includes power costs which assume $0.07/kWh. Other 0&M costs based on 1% of total electrical and mechanical capital costs.
Salvage = 50 year life of non electrical and mechanical equipment.
3. Assumes inflation = 4% and interest=7%
It is important to note that the City is currently investigating a brewery waste source that could potentially
provide carbon in lieu of methanol. In addition, the City is also considering Micro-C as a back-up source of
supplemental carbon. The additional storage and feeding requirements for these alternative carbon sources
should be considered and evaluated further during preliminary design.
Understanding that additional investigation may alter the final design, for the purpose of determining costs,
treatment layouts, and schedules, the 4-Stage Bardenpho process with 75 gpd methanol addition was the
Brown,,-- Caldwell 4
TM5 Recommendations and Costs-Final-10-12-12 docx
Costs and Recommendations
selected alternative to meet the current permit limits. While meeting these daily ammonia and nitrate limits,
the annual median TIN limit is also met. This alternative was carried forward in the evaluation of
phosphorus removal and TIN compliance alternatives for Regulation 85.
1.3 Summary of TM3 - Regulation 85 Compliance
With the annual median TIN limit addressed with the recommended 4-Stage Bardenpho process in TM2,
TM3 focused on treatment options aimed at meeting the Regulation 85 TP-P requirement of 1 mg/L as a 12-
month moving median value.
The evaluated treatment options were grouped into the following categories:
• Biological Phosphorus Removal Options
• Chemical Phosphorus Removal Options
• Phosphorus Removal and Recovery Options
The most suitable alternatives to meet Regulation 85 are listed below in Table 4 along with the advantages
and disadvantages of each. Important benefits and disadvantages are highlighted in green or red,
respectively.
Table 4. Regulation 85 Selected Treatment Alternatives
Biological Phosphorus Removal Options
Description Pros cons
• Influent carbon is insufficient for nitrogen removal,
therefore definitely insufficient for appreciable P removal
• Potentially uses influent carbon forbio-P • Chemicals are required to supplementdenitrification
4th Basin Bio-P • Original design intent and P removal
• Additional ammonia release impacts peak day effluent
ammonia
• Increased potential to develop struvite
Chemical Phosphorus Removal Options
Description Pros Cons
• No major treatment changes • Addition of precipitating chemicals upstream or within
• Lowcapitalcost biological treatment sequesters soluble P04-P which
Inhibits the nitrifiers. There would be areal danger of
Secondary Clarification violating the peak effluent ammonia requirement.
• Increased solids loading requiring a 5th clarifier
• EffluentTP is related to the effluentTSS
• Proven to achieve <0.05 mg/L without filtration. • Requires additional unitprocess downstream of the
Therefore easily achieves < 1 mg/L secondary clarifiers
• Highly effective effluent TSS polishing • Additional chemical (magnetite) handling required
Post Precipitation with Metals removal
CoMag • The degree of P removal can be directly "dialed-
in" by adjusting the alum dosage
• Compactsystem
• Doespot inhibit the biological process
BrownANI)Caldwelt 5
TiN15-Recommendadons and Costs Final-10-12-12 docx
Costs and Recommendations
Table 4. Regulation 85 Selected Treatment Alternatives
Phosphorus Removal and Recovery Options
Description Pros Cons
• OstaraPearl®, • Providesthe potential forrevenuewith sale of the • Additional unit process
• Multiform Harvest recovered product • Without bio-P operation the process maybe less than
• Crystalactor • Reduces the mass of Pthat needs to be removed optimal
in the liquid stream process; reduces alum and
alkalinity dosages
• Reduce struvite precipitation potential
Based on the evaluation and alternative cost comparison, the 4-Stage Bardenpho (recommended in TM2)
with CoMagO and Ostara Pearl@ is the recommended treatment alternative to meet the Regulation 85
permit limits. These costs (for the addition of CoMagO and Ostara Pearl) will be carried forward for the
overall project schedule. Details on the evaluation, layouts, and cost estimates are provided in TM3.
Table 5 presents the estimated costs for these treatment technologies. The costs associated with the 4-
Stage Bardenpho process and methanol facilities are not included in these costs since these facilities would
be installed prior to this upgrade project.
Table S. Esklilit&W Costs for 4-Stage 13ardenpho + O , ; ,
Capital Cost Annual O&M Costs 20-Year
Total Total Cost Present
Annual 20-Year Salvage (Capital + Worth
Present a 0&M PW Revenue
Ostara Operating. Value
Comag® Total E Q Cost Worth 1 Salvage) from
Pearly 0. Ostara
$10,778,000 ~$3,945,000I$14,723,OOOI$663,OOOI$7,800I$92,700I$763,500 $11,360,000 $3,270,000I$22,813,OOOI$210,000
1. Assumes inflation = 4% and interest =7%.
2. Other O&M costs were taken as 1% of capital for routine maintenance and parts replacement for mechanical and electrical equipment.
3. Includes power costs which assume $0.07/kWh.
4. Salvage value was assumed to be 0% for mechanical- and electrical-related equipment after 20 years, and 60% for non-mechanical equipment
after 20 years.
The City is also interested in chemical addition in the secondary clarifiers since it was the lowest-cost option.
It is recommended that the City staff test this option first as a proof of concept to understand the
downstream treatment impacts.
Understanding that additional investigation may alter the final design, for the purpose of determining costs,
treatment layouts, and schedules, the 4-Stage Bardenpho process with CoMagO and Ostara Pearl@ was the
recommended alternative to meet the Regulation 85 permit limits. These processes were carried forward in
the evaluation of phosphorus removal and TN compliance alternatives for Regulation 31.
6
TM5 Recommendations and Costs-Final-10-12-12 docx
Costs and Recommendations
1.4 Summary of TM4 - Regulation 31 Compliance
To meet the Regulation 31 limits, the 4-Stage Bardenpho process would be utilized to achieve the lowest
secondary effluent concentrations of both nitrogen and phosphorus without chemical addition. The reasons
are as follows: 1) to meet the limits expected for Regulation 31, additional nitrogen and phosphorus removal
will be required after secondary treatment; 2) utilization of carbon and coagulant for nitrogen and
phosphorus removal, respectively, will be more efficient if carried out in dedicated post-denitrification and
post-precipitation facilities.
The evaluated treatment options were grouped into the following categories:
• Past-Denitrification Options
• Dissolved Organic Nitrogen (DON) Removal Options
• Phosphorus Removal Options
The most suitable alternatives to meet Regulation 31 permit limits are listed below in Table 6 along with the
advantages and disadvantages of each. Important benefits and disadvantages are highlighted in green or
red, respectively.
Table 6. Regulation 3 1 Selected Treatment Alternatives -J
Post-Denitrifiication Options
Description Pros I Cons
• Wealth of priorexperience with Denlte0 filters in the • Low filtration rates require relatively large land area.
U.S. for post-denitrification. • Umited solids handling capacity under upset
Deep Bed Denitrification Filters
• Provide tertiary filtration and reduce secondary conditions in secondary treatment
effluentTSS and P.
• Denitrification MBBR plants visited with • System requires sieves and mechanical mixers to
Littleton/Englewood personnel in Germany and prevent media migration.
Scandinavia for possible implementation atthe . No retention ofTSS in this system (not a
plant Many years of successful operation at these I disadvantage in this case).
plants.
• Operating plants in the U.S. meeting less than 1
MBBR mg/L NOx-N.
• Low profile suspended media system with simpler
civil construction.
• No filter or media blinding issues. Reduced impact
of suspended solids carryoverfrom secondary
treatment.
DON Removal Options
Description Pros Cons
Enhanced Coagulation Process can be incorporated with chemical P • Removal is limited.
removal. • Not determined as yet, but removals could vary
• Least complex and lowest cost option. seasonally.
• pH conditions forDON "precipitation" and . rurtherongoing laboratory testing is recommended.
adsorption correspond with requirements for P Large amount of chemical sludge may be
removal. produced-more than produced for P removal.
• Pilottesting is not essential.
Microfiltration (MF) or Probably the hest removal of the options. Known to be the mostexpensive option.
Ultrafiltration (UF) plus Reverse • No sludge generation. • High energy requirements.
Osmosis (RO) • Treatment is compact. • A large reject stream (probably 20% of the total flow
• No upstream P removal required (RO will accomplish to the membranes) must be disposed of.
both DON and P removal. It will also accomplish Treating or processing the reject stream could be as
7
Costs and Recommendations
Table 6. Rdp[Atton3lSelectedTreahnentAftemagm
some NH3-N and NOx-N removal, so the RO may big a challenge as removingthe DON.
eliminate more than one of the post secondary • If the reject stream is recycled back to the
processes. headworks, the overall treatment flow through the
plant would increase by 20%. The membrane system
would also be 20% larger than the influent flow.
• It is essential to pilot this process to determine the
best membrane and to determine the actual DON, P
and NOx-N removals.
Phosphorus Removal Options
Description Pros Cons
• High specific gravity of magnetite ballastprovides • Requires materials handling for magnetite addition
high stabilityof the process under peak flows and and magnetite recovery equipment,
solids loads. • High performance of Maynard WWTP required
• Proven process demonstrates very low P and consultant (Brown and Caldwell) intervention in
turbidity without filtration. design of the clarifiers (rectangular designed
CoMago • Proven process handles very high peak flow and instead of vendor'scirculardesign).
solids load ratios, with minimal impacts to effluent
quality.
• High shear mixer for magnetite recovery does not
require pre-screening.
• Lowest area requirement of the altematives.
Based on the evaluation and alternative cost comparison, the recommended alternative for meeting
Regulation 31 limits is utilizing the 4-Stage Bardenpho (recommended in TM2) and CoMag® system
(recommend in TM3) with MBBR. The CoMag® system (installed in the previous phase) also provides a
good option for DON removal along with TP removal. The system is a good investment for the future as it can
continue to be used to meet Regulation 31 TP limits. The size of the CoMag® system does not need to be
increased from Regulation 85 requirements but additional chemicals (e.g., alum, sodium hydroxide) will be
required to meet the Regulation 31 limits. Details on the evaluation, layouts, and cost estimates are
provided in TM4.
Table 7 presents the treatment costs for the MBBR system with additional chemicals used in the CoMag®
process. The costs associated with the CoMag® system are not included in the capital costs since this
system would already be in place the facility needs to comply with Regulation 31.
1 W mated Costs for and I O Increased with ChemIcal Addition
Annual O&M Costs
Total Capital Cost' a Total Annual 20-Year
Salvage Value 5 Total Cost
.fW c Operating Cost Present Worth 2
U a o
$8,861,000 f $599,000 $104,900 $58,500 $762,400 $11,340,000 $1,810,000 I $18,391,000
1. CoMag® capital and 0&M costs have been accounted for under TM Regulation 85 and are not included in Table 7.
2. Assumes inflation = 4% and interest =7%.
3. Other 0&M costs were taken as 1% of capital for routine maintenance and parts replacement for mechanical and electrical equipment
4. Includes power costs which assume $0.07/kWh.
5. Salvage value was assumed to be 0% for mechanical- and electrical-related equipment after 20 years, and 60% for non-mechanical
equipment after 20 years.
• • $
TW&Recommendations and Costs Final 10 12-12 docx
Costs and Recommendations
2. Recommendations and Project Approach
Based on the findings from this study, it is recommended that the treatment alternatives be constructed in
three separate projects. The recommended alternatives to meet future requirements are listed in Table 8.
Table 8. Recommended Pmlects
Project Regulation Compliance' Target/Goal Description
Current Permit Limits Daily NH3-N < 1.9 mg/L
1 Daily N03-N < 14.7 mg/L 4-Stage Bardenpho with methanol facilities
Regulation 85 TIN Limits 71N-N < 15 mg/L
2 Regulation 85 TP Limits TP-P < 1.0 mg/L CoMag@ with Ostara Pearl@
3 Regulation 31 Limits TN-N < 2.01mg/L MBBR with increased chemical dosage for CoMag®
TP-P < 0.17 mg/L
1. See Table 1 for compliance frequency.
2.1 Site Layout
The recommended treatment technologies to meet the current and future permit limits are shown on Figure
1. The proposed locations on the facility site are sized based on preliminary design information noted in the
respective TMs. The processes and facilities are color-coded based on when the project is scheduled to be
implemented: red for current permit limits, green for Regulation 85, and yellow for Regulation 31. Individual
preliminary layouts of the selected alternatives can be found in the respective TMs.
Chemical Delivery ° CoMagOs Facility
'R s (Lf]0' X 1000
- Y.. .e t'
~e►f tai rl ~ ~ E ~ ~ y~.
Bardenpho a
-
j-~ , dF rl g"yy : Ir
M!J
aninc =EEL
• . I t`.;
_ MeOH Storage
'~A&
-174
A i+ ~,~k ~-s. wY ~~f y , i~'~'~~i1LJls~f►11~t~
Figure 1. Site Plan with Recommended Treatment Technologies.
Brown.NDCaldwett
9
T 5-Recommendations and Gosts-Final-10-12-12.docx
Costs and Recommendations
3. Project Costs and Schedule
Based on the estimated project capital costs, a schedule of design and construction activities along with the
associated costs were determined. The timing and costs of these project activities are presented below in
Table 9. Details on the calculated project costs are provided in Appendix A.
Table 9. Compliance Schedule and Project Costs
Treatment Technology Time Period Activities 2 Total Cost 1
Project 1: 4-Stage Bardenpho 2013 Optimization $ 0
with Methanol Pre-Design and Final Design For Current
2014 Limits $ 206,400
Li
Capital Cost: $1,376,000 2015 Construction $ 1,651,200
Total Project Cost: $1,898,880
2016 Startup/Testing For Current Limits $ 41,280
2017 Regulation 85 Related Pilot Testing $ 0
Project 2: CoMag® with Ostara 2018 Pre-Design For Regulation 85 $ 736,150
Pearl® 2019 Final Design For Regulation 85 $ 1,472,800
Capital Cost: $14,723,000 2020 Construction $ 8,833,800
Total Project Cost: $20,317,740 2021 Construction $ 8,833,800
2022 Startup/Testing For Regulation 85 $ 441,690
Project 3: MBBR and CoMag® w/ 2026 Regulation 31 Related Pilot Testing $ 0
Increased Chemical Dosage 2027 Pre-Design For Regulation 31 $ 443,050
Capital Cost: $8,861,000 2028 Final Design For Regulation 31 $ 886,100
Total Project Cost: $12,228,180 2029 Construction $ 5,316,600
2030 Construction $ 5,316,600
2031 Startup/Testing For Regulation 31 $ 265,830
1. Pre-Design = 5% of capital cost. Final Design =10% of capital cost. Construction cost includes capital cost + 5% for administrative and legal
fees + 15% for construction management. Startup/Testing = 3% of capital cost.
2. For Projects 2 and 3, construction costs occurred were based on 24 months and the total capital cost was spread over two years.
4. Recommendations for Bench and Pilot Scale Tests
This Study evaluated a number of alternatives and made recommendations after weighing advantages and
disadvantages and estimated costs. However, there remain some questions that can best be resolved by
bench and/or pilot scale evaluations. Based on the evaluations, the following lists the recommended tests
that would be beneficial to the City for future plant modifications and additions. Detailed protocols would
need to be developed for each of the tests:
1. DON Removal Tests. Because of the importance of DON for meeting potential Regulation 31 limits,
Brown and Caldwell prepared a detailed protocol for conducting the tests using enhanced coagulation.
The City has already applied this protocol and conducted tests. However, it is important to repeatthese
tests periodically (say on a 3 - 6 month schedule) to develop a sufficient database to provide surety that
the eventual design will be well founded.
2. Bench Tests for Post Phosphorus Removal. Post phosphorus precipitation will be required for meeting
Regulation 31 limits, and possibly for meeting Regulation 85 limits. It is important to conduct bench
M,- to 10
' •
T,M5 Recommendations and Costs-Final-14-12-12.docx
Costs and Recommendations
scale jar tests to determine the effectiveness and conditions required to meet different effluent
requirements. There are a number of phases that are important to follow:
a. Conduct the tests on secondary effluent using aluminum sulfate and an appropriate number of
polyaluminum chloride products. If ferric based coagulants are used then it would be important
to monitor the ultraviolet (UV) transmittance, because of the new UV disinfection system.
b. Conduct the tests using sludge generated at the Boulder water treatment plants. There may still
be significant adsorption sites on the sludge particles that could reduce the amount of virgin
coagulant required to meet treatment goals.
3. Bench Tests for In-Basin Phosphorus Removal. Conduct tests using virgin coagulant and water plant
sludge, but applied to mixed liquor. This series of tests is important to evaluate the conditions required
to meet Regulation 85 phosphorus limits, if coagulant (or water sludge) is applied to the secondary
clarifiers. Parameters such as required pH correction and increased total solids are important.
4. Bench and Full-Scale tests to Enhance Secondary Clarifier Performance. An operational issue
occasionally experienced at the plant is relatively high secondary effluent TSS. A number of jar tests
should be conducted using polyaluminum chloride blends and/or organic polymer products. The most
cost effective products should be determined. Additional tests could include the use of magnetite with
and without polymer, and talc, with or without polymer. After optimization of a short list of appropriate
products, short term full-scale tests could be conducted on one clarifier. This will allow standby means to
resolve solids overflow issues when they arise.
5. Improved Zone Settling Tests to Supplement SVI Tests. Some material has already been provided by
Brown and Caldwell to the City in this regard. It is important to initiate these tests and develop a
database for future plant improvements. Information on the required equipment has been provided to
the City by Brown and Caldwell. Guidance on the use of the equipment and interpretation of the data
obtained can be provided by Brown and Caldwell.
6. Bench Tests to Determine Primary Sludge Fermentation Potential. Primary sludge fermentation using
the OWASA process was found to be less expensive on a life-cycle basis than the use of methanol, for
equivalent denitrification potentials. It would be important to conduct bench tests using adapted
laboratory equipment to determine the volatile fatty acid generation potential of fermented primary
sludge, thereby verifying the assumptions behind the preliminary sizing and the cost estimates.
7. Filtration Pilot Tests for Post Nitrification. One of the most challenging treatment requirements faced by
the City is effluent ammonia. There is reliable evidence that by aerating secondary effluent and passing
the flow through a fixed film medium, significant post nitrification is obtained. A very worthwhile
"research" project that could be conducted in the short term is to evaluate the removal potential of such
a fixed film system. It is conceivable that the University of Colorado may have a pilot filter that could be
loaned, or used as part of a final year or master's thesis project. In any case, this information would be
very useful to the City since the results may present a means to help meet the stringent limits. The
availability of a currently unused nitrifying trickling filter at the plant may offer a means to make such an
approach viable.
• • 11
MIS-Recommenclations and Costs Final 10-12-12 docx
Costs and Recommendations
5. Summary
The key questions of this Nutrient Compliance Study were to determine what treatment upgrades are best
suited to meet the increasingly demanding nutrient removal requirements from the three regulatory actions,
and when to implement these phased treatment upgrades. As a result of this evaluation, the City of Boulder
and the Brown and Caldwell team have selected the best treatment alternatives to meet the current and
future permits limits. These treatment alternatives optimize and utilize the existing facility, each treatment
technology builds upon and compliments the future technologies, and there are no stranded investments.
The team has also established a phased schedule to implement these three projects, and the related cost
estimates will help to establish the City's upcoming Capital Improvements Plan to maintain compliance for
the next 20 years.
• - 12
M15-Recommendations and Costs-Final-10-12-12.docx
Costs and Recommendations
Attachment A: Project Costs
Brown,,,~~, Caldwell A
V.1_ ;iinenua,! ins ~ii,LJ Cos's-Ruch DJ 1 d-Ir.Jec-,
This page intentionally left blank.
Boulder 75th Street WWTF TM5
Nutrient Compliance Study Appendix A
Project • • • +
Total Construction Cost $1,376,000
Other Professional Fees
Engineering
Pre-Design 5.0% $ 68,800
Design 10.0% $ 137,600
Administrative and Legal 5.0% $ 68,800
Construction Management 15.0% $ 206,400
Start-up 3.0% $ 41,280
Subtotal $ 522,880
Total Project Costs
Total Project Cost $1.,898,880
Total Construction Cost 514,723,000
Other Professional Fees
Engineering
Pre-Design 5.0% $ 736,150
Design 10.0% $ 1,472,300
Administrative and Legal 5.0% $ 736,150
Construction Management 15.0% $ 2,208,450
Start-up 3.0% $ 441,690
Subtotal $ 5,594,740
Total Project Costs
Total Project Cost $ 20,317,740
' • • i • • it . fC
Total Construction Cost _ $ 8,861,000
Other Professional Fees
Engineering
Pre-Design 5.0% $ 443,050
Design 10.0% $ 886,100
Administrative and Legal 5.0% $ 443,050
Construction Management 15.0% $ 1,329,150
Start-up 3.0% $ 265,830
Subtotal $ 3,367,180
Total Project Costs
Total Project Cost $ 12,228,180
Wastewater Treatment Facility
Nutrient Compliance Study
Update
_ -
WRAB MEETING
NOVEMBER i9, 2012
CHRIS DOUVILLE
AND
DOUGLAS SULLIVAN
NCS Agenda
.
■ October 2012 WRAB Review
■ Study Overview
■ Treatment Requirements
■ CIP Impacts .
■ Summary/Next Steps
Oct 202 WRAB Meeting Review
0
Regulatory Status & Compliance Risk
■ Nutrients (N & P)
Arsenic
■ Temperature
■ Copper
Nutrient Compliance Study Goals
0
• Determine Treatment Upgrades
■ Identify Phased Implementation Plan
■ Develop Budget Level Cost Estimates
Nutrient Compliance Study Tasks
- - - - - - - -
1. Existing Facility Evaluation
2. Current Permit Compliance
3. Regulation 85 Compliance
4. Regulation 31 Compliance
5. Recommendations & Costs
Technical Memorandums
Regulatory Overview
0
■ May 1, 2011- Current Permit
■ Dec 2017 compliance schedule
■June2012-Reg 85&Reg31
■ Regulation 85 - 2022
■ Regulation 31- 2030
*estimated compliance schedule
Current Permit
■ More restrictive ammonia and nitrate limits
■ Current WWTF process could not reliably meet
new limits
■ "Looking Back" 3-year trial period
■ 27 ammonia violations*
45 nitrate violations*
I
*based last 3 year's plant performance
I
Regulation 85
Total Inorganic Nitrogen (TIN) and Total
Phosphorus (TP) limits for WWTFs > 1 mgd
■ Current WVVTF process could not meet Reg 85
limits
■ Reg 85 TP Limit =1 mg/L
■ Current WWTF Performance = 3.5 mg/L*
*based on last 3 year's plant performance
Regulation 31
■ Extremely restrictive (love) effluent limits*
■ Proposed TN limit= 2.01 mg/L
■ Proposed TP limit = 0.17 mg/L
proposed limits are at or near industry threshold for treatment
Nutrient Permit Limits
0
Ammonia-Nftpn (mg/4
Phase DaU Uk%t a NbaDo-NftW TIN-Ntrogen 1IN-Nitrogen TF-Rimphorus
(mg/4 (mfJ4 (mg/4 09/4
Chronic AwW
Current May 1, 2011 5.3 15.3
Eidstinq
PerrriC - - -
Campllance Dec 1, 2017 1.9 1.9 17.9 / 14.7
Schedule
Regulation 85 Approx 2022 1.9 1.9 17.9/14.7 15 1
I
Existing Facility Configuration
Raw Influent
Primary Influent
Primary Effluent WWI
A-Basin Effluent
c Z4 - PAS Flour
f" MLWAS Plow
Secondary Effluent
Final Effluent
Primary Sludge
y -A. Th"enedSludge
Lf _._r•! ;J. Cake Blosoiids
w aar>rw
113- _ X111 a
Ammonia Treatment (N Conversion)
r~
~l
Am 95% AW
wnr r_ J Se s~ 4. 1
..r~rr>ra~ ~ _
' I~iY1~i C" f •i.
~1t1T1!!LA- .
- ti r ° 1
L^
~ _Y
„'r. ,_r a
s r• C - ^C tiY
Nitrate Treatment (N Removal)
Jrl~
.~A~ 1.
`S to s . Q ;,e ; .
I W.
gMttWJFM"
MMA JJ f 7
~lip
Phosphorus Treatment
J1f t y~ L~' l .1~ 1 J r t l a! 1
/ice
Ara
` ~ J'-
• ~ Yom--., - - _ -
L
Improve Ammonia Performance
C
• Further equalize ammonia load
Modify dewatering schedule
Improved management of centrate return
• Increased vigilance for microorganism inventory
• No fail-proof technology
There will remain a significant compliance risk to manage
Improve Nitrate Performance
0
• Perform optimization efforts
Minimize D.Q. entering anoxic zones
• Find more readily biodegradable carbon
In-plant sources may be limited
Commercially produced carbon sources have tradeoffs
Some hope for local (Boulder) source (i.e. Avery Brewing)
• Implement 4-stage Bardenpho process
Overall minor modifications to the current reactor
configuration
Improve Nitrate Performance
' M1 Relocate Convert to Anoxic
Wall Pumps Zone (Typ. of 3)
f: t McOH Tpof 3 Cap Diffusers ;
lAddition
= i
y,- f a
(Typ. of 3) 7--~ New
o fl r '
a
~ o
Mlxersi McOH Delivery
a 0, I I
Tie into MeaH Pump
ExistinglMLR Station and
(Typ• of 3) Storage Tanks
f: ' • f5 tl:h. WaY •.V : NJ1'5:.,V•
lr= ~
4-Stage 6ardenpho 131
Phosphorus Removal Strategies
• Chemical P Removal
Reliable, proven, expandable.
• Implement Siemens CoMag ® Process
Ballasted flocculation/sedimentation with magnetite
P removal, as well as TSS and metals removal
Easily expandable for Regulation 31
• Implement Ostara Pearl ® P Recovery
Forms phosphorus crystal (struvite) for fertilizer
Retrofit in existing building
CoMag ® P Removal Process
~ • trtLineSheaz - - -
;rl;,gnei ne
M1tngnoii,e ► To5ltxlgC ~
Recuvery Processing
Pulynwr Vnim
III , C .
Raw ~Fa,er i ~ ~ ~ ~
~y i ~ Firtnt
rMilonq
sludgy RvCyck. `
ostara Pearl ® P Recovery
TREATED
CENTRATE
■ EFFLUENT
RECYCLE
1 LINE
CENTRATE
INFLUENT
Total Nitrogen Removal Strategies
0
Maximize N/DN process with 4-stage Bardenpho
Assumes already in place
• Implement tertiary MBBR process
Moving Bed Biofilm Reactor - removes remaining nitrate
Effluent TIN < 1.o mg/L
• Utilize CoMag ® process for MBBR effluent
Assumes already in place
CoMag removes dissolved organic nitrogen (DON) that isn't
biodegradable
TN Removal Strategies
Pumps Chemical Delivery
CaMag(D Facility
(160' X 100,)
. J p X
/ ICI o rtn ~.^rhl
- 6:X.1 f 4 h'JT?:l i Y" ST l:.Y -
-Allemalwe 1 PABBR am C061ag 81
w: - ,>A,:~cEs~~ ~
Impact of New Limits?
■ New projects required to address all three permit
cycles:
■ Current Permit - Before 2017 = $1,900,000
■ Regulation 85 - Before 2022 = $18,000,000
Proposed Site Layout
i
r. .tr
Ohm%
0001 C:M
l` 1 "d.
----s_ 4 r
-10
77
'k J
Project Funding by Year
- - - - - - 0 - - - -
TreafinentTedmolO& Time Period ACUMN Total Cost
2013 Optimization $ 0
Current Permit 4-Stage Bardenphol 2014 Pre-Design and Final Design For Current limits $ 206,400
with Methanol
Capital Cost $1,376,000 I 2015 Construction S 1,651,200
Total Project Cost, SL898,880
2016 Startup/Testing For Current lJmlla $ 47.280
2017 Regulation 85 Related Pilot Testing $ 0
2018 Pre-0esign For Regulation 85 $ 736.150
gegu!atlon gs; Confag~ w}th 2019 Friel Design For Regulation 85 S 7.472,800
Ostare PearlO 2020 Construction $ 8,833,800
Capital Cosh$14,723,00D -
TotalPrgadCoatS20,317,740 2021 Construction $ 8,833,800
2022 Startugr70s1!ng For Regulation 85 $ 447,690
MBBR and CoMag®
w/ Increased Chemical Dosage
Capital CaatS8,861 DDO
TotalProjeaCcst:$i2 JM
i
6-Year CIP (Permits)
$1,800,000 - - - -
$i,6oo,0oo - - - -
$1,400,000 - - - -
$1,200.000 - - -
1$1,000, 000
0
4 $800,000 4
$6oo,ooo
$400,000 -
$200,000 f-_ _ - -
$o ■
2014 2015 2016 2017 2(118 2019
Year
20-Year CIP (Permits)
$10,000,000
$9.000,000
$8,000,000 - -
$7,000,000 !
l
$5,000,000 i
O
❑ $4,000,000 -
i
l
$3,000,000 j -
$2,000,000 - - -
$1,000,000 - - - -
2014 2o1S 2o16 2017 2018 2019 2020 2021 2022 2023 2024 2o25 2o26 2027 2028 2029 2030 2031
YEAP
Estimated Project Costs
- Total Annual 20-YearO&M Total Cost
Operating PreserrtWorth Salvage Cost (Capbl+O&M
Cost PIN - Salvage)
RecommendedARernative Total Chemical Power Other
Current Permit i
4-Stage Bardenpho S1,376,000 $44,000 $22,600 $8,300 $74.900 $1,110,000 $534,600 S1,95I.000
with Methanol racil ty
Regulation 85
CoMagO with S14,723,000 $663,000 $7,800 I $92,700 376 ,500 $11,360,000 53,270,000 $22.813,000
00ara Pearl®
$8,861,000 $599,000 $104,900 I $58,500 $762,400 $11,340,000 $1,810,000
MBBR
I
Summary
NCS identifies three upcoming.projects
1. Current Pernilt
• Tough daily max issues
Sets up the WWTF well for N removal (Reg 85)
2. Regulation 85
• Phosphorus only
• Sets up the WVVTF well for P removal
3•
Extra Nitrogen removal (MBBR)
Next Steps
WRAB:
• NCS Final Report - Available January 2013
• May 2013 - CIP budget review and approval
• Ongoing
Updates via "matters", as appropriate
City Staff:
• Data collection and monitoring - ongoing
Official Reg. 85 nutrient monitoring starts March 2013
• 2013 - optimization activities
Questions
r
Supplemental Carbon Summary
External Carbon Alternatives Analysis Summary Cale Sigmon
Process Optimization Specialist
75th Street Wastewater Treatment Facility
COD (mg1L) COD/N Gallons/day Cost/gallon Truck
delivery per
methanol 11188,0DD 4.28 75 $ I.59 84 days
MicroC2000 1,040,000 5.1 102 $ 2.35 60 days
Brewe WW 45,000 4,29 1,989 $ 0.037 3 days
AnnualGHG 20-year present Total2iJ-yaJrprfacnt
Annual Cost Capital Cost 20-yearpresent AnnuaIGHG EU Market valueofGHG vc,lue(lnclediiigGH3
value em (kg C02eq) Price emissions emf_=-.fans EU msrr.=t
value:.)
Methanol 5 43,599 5709,743 5237,628,472 62,704$ 508.53 $ 7,565.58 $ 237,636,037
MicroC2000 $ 87,746 $ 155,000 $ 476,968,772 18,984 $ 153.96 $ 2,290.50 $ 476,971,063
Brewe WW $ 26,631 $ 155,000 $ 144,869,921 7,691 $ 62.37 $ 927.96. $ 144,870,849
Current Permit Treatment Options
c
- - - - - - 0 -
Options to Meet Effluent Permit Limits
Description 'Pros (Cons
Same operational process Supplemental carbon facilities
Existing MLE process Utilize existing basins required
Less expensive capital costs C gtgen O&M (chemical
New operational practice
lm. Jtaneous Si nificantenergy savings Additional controls required
itntrF~Yio 11] izeexisting basins Possible impact on settleabillty
DenitrnlCat JOn (SND) Reduce carbon deficit Carefp balance of
nits :cation/denitrification
required
r~ Utilizes existing basins Reqctuire minor aeration basin
.---3 4~rith ar ~Barrdoenpho Better utilizes ree influent rrtoditications, such as Ir
Seco dAnozicZone carbon than current constrpction ofa gewchimney a
configuration baffff~le in each basin
New infrpstructure and large
Addit~'o ffluentTSS removal footpnnt
W-Penitrifcation wdh NAFTs New processoperaltion
m~~ Expandable to meet Reg 31 High cost pompared to other
alternatives
Current Permit Treatment Options
Table2, Current Permit Limit Selected Treatment Alternatives
Optionsto Address Peak Excursions
Description Pros :Cons
Requires a ualization of the
Nitritatiotnl Anammox Reduces carbon deficit centratestream
F entrat 7g~tment Reduced nitro en load to New operational practice
e g DEN) aeration bans Additional controls
Reduced power New infrastructure
High cost
prima Effluent Off- No additional treatment or Canny;: ;i,ualizeentire influent
Spec ream processes required ammu!ita load
zaea n (PESTS) Reduces efflvent-peaks Additional controls
qual Utilize existing PTS programming/ Vonitoring
Options to Address Carbon Deficit
Description (Pros Cons
ft~~ of Re ud cstergas -
Partial
suppfeductfoementalcarbondeficit Production
ppWASA e e ted lowest life-cycle cost compared Standbycarb0n addition
Primaryfludges ith purchased i ethanol, for recommended
t el sse massOT nitrogen Odor control required
remova High capital cost compared to
chemical facilities
Fluctuating costs L_
Purchase Carbon Good consistency of product General safety concerns
Potential flammability Yip A
Regulation 85 Treatment options
0
Table 4. Regulation 85 Selected TreatmentAltervatives
Biological Phosphorus Removal Options
Description Pros Cons
Influent carbon Mnsuffictent
for nitrogen removal,
therefore definitely
Insufficient for appreciable P
removal
4s' Basin Potentially uses Influent Chemicals are required to
B10-13 carbon for bio-P supplement denitrification
Original design intent and P removal
Additional ammonia release
impacts peak day effluent
ammonia
Increased potential to
develop struvite
r r
Regulation 85 Treatment Options
0
Chemical Phosphorus Removal Options
Description Pros Cons
No capital cost treatment changes Addi preQi Ii J is I treatment
Low capital cost u strea stream ❑ it
rwit~un s I is ~ treatment
sterss lu le w is
nl, is the nitrt I~rs. h re would be a
g5 qnry re an er of vip atin tnhe peak
Ctacnlieatidoon effluent mmonia req cement.
Increased solids loading requiing a 5th
clarifier
EffluentTP is related to the efFluentTSS
Vover-to Gfi i ye 0U Rde wires additiot~ aI unit process
i wi~Itaut ti tr
a tion. here ore easily ownstream otthe secondary clarifiers
achieves{me/l. AdditipnatEchemical (magnetite)handling
/A Highly Pffective effluent TSS required
`r East 111Ss ing
rN' pp Metals removal
with it, lion Th~~ a y deA~e of P r rpoy Ica be,
g t}ir 'Oralee in ~iyac usting .
Osage
Compact system
Does not i n h obit the biological
process
Phosphorus Removal and Recovery options
Description Pros Cons
Ostara Pearl(g, Provides the tential for r venue Additional unit process
i M ltiform wrth sale o~tie recovered product Without bi -P opelati n the process may 1
' Harvest Reduces the as of p th t needs to be less than optima - -
' Crystalactor be removedpn t e lJqui st earn
p ocgs~; reduces alum an
a~kahnity osages
Reduce striwite
potential tial
Regulation 31 Treatment options
. c ~
Tabil Regulation 31 Selected Treatment Alte rinallives
Post- Den itri fication options
Description Pros Cons
Weattii ol^pritexperiencewith I {d; . . i ._s require iel rely
Deep Bed Denite®fiblters in the U.S. for post- large land area.
DentrificationFllters denitrification. Limited solids handling capacity under
Provide tertiary fdtrat on and reduce: upset conditions in secondary
seeondaryellluentTSSand P. treatment
DenitrificationMBBRplantsvrsrted System requires sieves and
with Littleton/En lewoodpersonnel mechanical mixers to prevent media
in Germany and Scandinaviafor migration.
possible implementation atthe No retention ofTSS in this system (not
plant Many years of successful a disadvantage in this case),
a operation at these plants. .4
` Operating plants in the U.S. meeting 1
MBBR less than 1 mg/LNOxA
Lowprofile suspended media system
wrthsimplercivilconstruction.
No filter or nn:dia Winding issues. y
Reducedinytactofsuspeoded
solids carryover from secondary
treatment.
i
DON Removal Options
Description Pros Cons
-ahan&dCoagu[atiou rote"ssean orated with Removal is limited.
chemical PremovaL Not determined as yet, but removals
Least complex and lowest cost option, could vary seasonalty,
pH conditions for DON "precipitation" Further ongoing laboratory testing is
and adsorption correspond with recommended.
requirements forP removal. Large anaunt of cliein,cal sludge may
Pilot testing Is not essential, bepror[ucerl-morethanproduced
- i for -removal. - - - -
i
Regulation 31 Treatment options
- -
Tablelli. Regulation 31 Selected Treatment Alternatives
Past-Denitrification Options
Micrdfiltration (MF) or Probably "the befit ierE oYafvfihe options.- 0oi,n to be be most c,epensive option.
Ultraflltraticn (U F) 41 us I NO sludge generation. High energy requiremerts.
Reverse Osmosis (0) Treatment is compact A large reject stream (probably 20% of the total
No upstream P removal required (RO will flato the membranes) must be disposed of.
accomplish both DON and P removal. [twill Treatiwng ,r processing the reject stream could
also accomplish some NH3-N and NOx-N be as big a challenge as removing the DON.
removal, so the ROmay ellminatemore than If the re1jectstream is recycled back to the
one of the post secondary processes. head-works, the overall treatment flow
through the plantwould increase b 20%.
The membrane system would also be 20%
larger than the influent flow.
It is essential to pilot this process to determine
the best membrane and to determine the
actual DON, Pand NOx-N removals.
Phosphorus Removal Options `
Description jPros (Cons
Requlres materials handling for magnetite
addition and magnetite recovery equipment.
High performance of Maynard NWTP required
High specific gravity of ma netite ballast consultant (Brown and Caldwell) intervention
provides high stability ofthe process under in design of the clarifiers (rectangular
peak flows and solids loads. designed instead of vendor's circular
Proven processdemonstratesvery low Pand design).
turbidity without filtration.
Collage Proven process handles very high peak flow and
' f
solids load ratlos, with minimal impacts to
effluent quality.
High shear mixer for magnetite recoverydoes
not require pre-screenln
Lowest area requirement of the alternatives. J
r E
CITYOF BOULDER
WATER RESOURCES ADVISORY BOARD
INFORMATION ITEM
MEETING DATE: Nov. 19, 2012
AGENDA TITLE: Information Item About the High Hazard Zone Regulations
PRESENTERS:
Jeff Arthur, Director of Public Works for Utilities
Bob Harberg, Utilities Engineering Project Management Coordinator
Annie Noble, Greenways Coordinator
Kurt Bauer, Engineering Project Manager
Christie Coleman, Engineering Project Manager
EXECUTIVE SUMMARY:
Each year in the United States, natural disasters, including flood events, take the lives of
hundreds of people, injure thousands more and cost billions of dollars in damage. The
risk of flash flooding is an important issue for the City of Boulder, primarily due to its
location at the mouth of Boulder Canyon and other canyon creeks. By the time an
impending major flash flood is identified, it will likely be too late to take any significant
action to protect structures or coordinate a thorough evacuation effort. As a result, the
city's flood management program primarily focuses on proactive efforts such as
improving drainageway capacities, ensuring that structures within the floodplain are
designed to help minimize damage, and attempting to minimize the extent to which the
highest risk areas are populated.
Many of the city's flood management program elements are based on the requirements
and guidance of the National Flood Insurance Program (NFIP). As an insurance provider,
the NFIP's primary focus is on minimizing impacts to structures. Recognizing that the
nature of our flood hazards also presents substantial risk to life safety, the City of Boulder
adopted the high hazard zone regulations in 1989 to supplement existing regulations
intended to protect structures. While the high hazard zone limits are delineated based on
areas where people are likely to be swept away by floodwaters, life safety protection is
implemented through restrictions on structures and parking where people are likely to be
at risk. The high hazard zone regulations place restrictions on existing and proposed
structures intended for human occupancy, prohibit substantially damaged structures
intended for human occupancy from being rebuilt after a flood, and outline a process
through which those property owners can petition the city to purchase their property after
a flood event.
AGENDA ITEM # VII PAGE-1-
At the Sept. 18 City Council meeting, two community members voiced concerns about
the high hazard flood regulations during the Boulder Creek Floodplain Mapping update
and requested a review of the regulations. This memorandum presents information about
the history and objectives of the city's high hazard regulations, how the high hazard zone
is implemented and its post-flood implications. At its Dec. 17 meeting, the WRAB will
be making a recommendation to City Council for the 2013 Work Program priorities. This
memorandum is intended to provide the WRAB with background information that may
be helpful in determining whether a review of the high hazard zone regulations is a
priority, and if so, what the scope of such a review might include.
BOARD AND COMMISSION FEEDBACK:
During the adoption process for the Boulder Creek Floodplain Mapping Update, two
community members expressed concern regarding the high hazard zone regulations and
requested that the city undertake a review of the regulations with specific attention given
to the post-flood property acquisition provision detailed in section 9-3-8 of the B.R.C. At
its Oct. 15 meeting, the WRAB agreed that additional information and a discussion of the
current regulations would be helpful in evaluating the request.
BACKGROUND:
Floodplain Regulations
The city's floodplain regulations were originally adopted in 1969 and underwent their
most recent comprehensive revision in 1989. Chapter 9-3-2 (Attachment A) of the
Boulder Revised Code establishes three specific flood zones used to manage and regulate
development and uses within the floodplain. These zones are the 100-year floodplain,
conveyance zone, and high hazard zone and are described as follows:
• the 100-year floodplain is defined as all land areas that have a one percent chance
of inundation in any given year;
• the conveyance zone allows for passing flood flows along the creek corridor
without increasing flood depths, redirecting flood waters or adversely impacting
land areas; and
• the high hazard zone is an area of the floodplain where the combination of the
depth and velocity of the water is expected to be too great for people to maintain
their balance should they be caught in a flash flood or attempt to cross a flooded
area.
The high hazard zone is the most restrictive of the three zones due to the significant life
safety concerns. No new structures or additions to existing structures intended for human
occupancy are permitted. Structures damaged by more than 50 percent are not allowed to
be rebuilt. Additionally, no new parking lots and no change of use of an existing non-
residential structure to a residential use is permitted. Structures located within the high
hazard zone will likely be subject to greater flood forces than other areas of the
floodplain. The intent of the regulations is not to protect the structures, but the people that
occupy and use the structures. By working to eliminate the number of structures in the
AGENDA ITEM # VII PAGE-2-
highest risk areas, the regulations seek to reduce the number of people who could
potentially be swept away by floodwaters.
History of the High Hazard Zone
The National Flood Insurance Program (NFIP) mandates i 00-year floodplain and
conveyance zone regulations (the NF1P calls the conveyance zone a half-foot rise
floodway). Consistent with the NFIP's mission, these flood regulations were created to
minimize property loss and are not directly intended to reduce flood risks to health and
safety.
In January 1987, City Council directed staff to investigate the areas of the floodplain
where the greatest life safety risks exist. The result of this research was an in-depth
theoretical analysis, a physical analysis and a peer review. Love and Associates
conducted a theoretical analysis to detennine an appropriate depth and velocity to use for
defining high hazard areas. The physical analysis and peer review were completed by
Colorado State University. The physical analysis included placing people in a hydraulic
flume to better understand the combinations of flood depth and velocity where people
become at risk for being swept away. This research is described in greater detail in
Attachments B, C and D.
Based on this research, it was recommended that the high hazard area be defined as the
areas in the 100-year floodplain where the flood water velocity (in feet per second)
multiplied by the flood water depth (in feet) would equal or exceed a product number of
four, or where flood water depth alone would equal or exceed four feet. Prior to adoption,
a sensitivity analysis was conducted along Boulder Creek upstream of Folsom Street.
This analysis demonstrated that the area of impact was not highly sensitive to the choice
of product number (using a range of product numbers from two to six, the area of impact
varied by approximately 10 to 15 percent). The high hazard zone regulations were
adopted in 1989.
The 2010 Boulder Valley Comprehensive Plan Update Policy 4.23, Protection of High
Hazard Areas, supports the high hazard regulations as follows:
"The city will prevent redevelopment of significantly flood-damaged properties in
high hazard areas. The city will prepare a plan for property acquisition of 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."
The high hazard regulations are listed in sections 9-3-5 and 9-3-8 of the B.R.C. and are
included as Attachment A.
AGENDA I'T'EM Vll PAGE -3
Implementation of the High Hazard Zone Regulations
In addition to regulating development, the high hazard zone designation is used as the
basis for prioritizing flood mitigation projects and pre-flood property acquisition. The
city also receives Community Rating System (CRS) credits for administrating the high
hazard zone regulation.
Based on the regulation, high hazard zone snapping has been developed for all major
drainageways in Boulder. Inside the city limits, there are a total of 180 structures located
in the high hazard zone. As a comparison, there are nearly 2,600 structures located in the
city's 100-year floodplain. During a 10-year storm event, inore than 50 percent of the
high hazard zone area would be inundated.
Boulder Creek and twelve tributaries include high hazard zone structures. The table
below provides a breakdown of the number of properties with habitable structures in each
drainageway:
High Hazard Zone Habitable Structures Located in Each Drainageway
Creek Habitable Structures in the
High Hazard Zone
Bear Canyon Creek 2
Bluebell Creek 2
Boulder Creek 31
Fourmile Canyon Creek 9
Goose Creek 44
Gregory Canyon Creek 26
Kings Gulch 1
Skunk Creek 22
South Boulder Creek 4
Sunshine Canyon Creek 4
Twomile Canyon Creek 22
Wonderland Creek 13
Total 180
The city allocates $500,000 each year for a pre-flood property acquisition program that
prioritizes the purchase of high hazard zone structures. A list of the highest-priority high
hazard zone structures has been developed based on risk factors. Every year, the city
mails a letter to each of these property owners to see if there are willing sellers. Ten
properties have been purchased since 2001.
High hazard zone mitigation is a primary consideration in prioritizing flood mitigation
and capital improvement projects. During the past 20 years, high hazard zone
improvements have been constructed on Boulder Creek, Goose Creek, Bear Canyon
Creek and Elmer's Twomile Creek. The city is currently designing a flood mitigation
AGENDA ITEM # VII PAGE-4-
project along Wonderland Creek from Foothills Parkway to 30`h Street and will soon
begin design of the next upstream reach to 28`h Street.
ANALYSIS:
The risk of flash flooding is an important issue for the City of Boulder, primarily due to
its location at the mouth of Boulder Canyon and other canyon creeks. Due to the very
short time frame in which flooding can occur, there is often limited time available to
provide adequate warning. In Colorado alone, 199 people have died in floods during the
last 50 years- Nationwide, flash flooding is the leading cause of weather related deaths,
with approximately 200 deaths per year.
While a separate high hazard flood zone designation remains unique to Boulder, a
number of peer communities including Ann Arbor, Michigan; Fort Collins, Colorado;
Madison, Wisconsin and Boulder County accomplish a similar result by prohibiting
construction intended for human occupation in a conveyance zone or floodway. Prior to
adoption of the high hazard zone regulations in 1989, the city had a similar regulation in
place. The regulation prohibited development within the conveyance zone and areas
having a depth greater than two feet or velocity greater than two feet per second during a
100-year flood event. City Council replaced this requirement by adopting the high hazard
zone regulations in 1989 in order to restrict development in unsafe areas based on a
scientific analysis of depth and velocity.
The high hazard zone defines the area where flood water would have at least enough
force to wash a person away. Some areas of the high hazard zone could be subject to
substantially higher forces that could have the potential to wash cars or buildings away.
Buildings located in the high hazard zone could suffer structural failures, or have issues
with fire, sanitation, electric hazards, broken utilities, or debris, subjecting people in
those structures to those significant safety risks. The high hazard regulations prohibit new
structures and expansions to existing structures intended for human occupancy in order to
minimize these life safety risks.
In many cases, high hazard structures are in such close proximity to a drainageway that
mitigation of flood hazards would require a highly structural approach, such as a concrete
channel or pipe. The emphasis on removing these highest-risk structures, rather than
taking drastic channelization measures to protect them, is consistent with broader
community objectives.
Post Flood Property Acquisition
Two community members voiced concerns with the high hazard zone regulations during
the Boulder Creek Floodplain Mapping update. A key area of concern was the post-flood
property acquisition provision. The regulation in question is included in Section 9-3-8,
BRC 1981 (Attachment A). This section outlines a mechanism through which a property
owner who is unable to rebuild a flood-damaged structure may seek to have the city
purchase the underlying land. The price would be based on fair market value following
the flood event.
AGENDA ITEM # V11 PAGE-5-
Since flood insurance policies cover structures, but not the associated land, the provision
potentially allows impacted property owners to reduce their flood losses. Insurance,
however, will only compensate for actual damage incurred to the structure, though sore
structures may be fully condemned. Any structure located in the 100-year floodplain or
the high hazard zone that sustains substantial damage is required to comply with the
city's current floodplain regulations. The Boulder Revised Code only provides a
mechanism for compensation by the city for properties damaged within the high hazard
zone.
The existing post-flood acquisition provision has never been utilized and there is some
uncertainty about how it would actually be applied. The city holds a reserved fund of
$1.05 million to purchase substantially damaged structures. After a flood event, this
funding would be leveraged with FEMA mitigation grant money to purchase high hazard
properties.
NEXT STEPS
At its Dec. 17 meeting, the WRAB will have the opportunity to make a recommendation
to City Council for the 2013 Work Program priorities. The WRAB could decide to
include a review of the high hazard zone in the priorities. The proposed scope of a review
would significantly impact the extent to which other work priorities would need to be
deferred.
Some options that the WRAB may wish to consider are outlined below.
Option I - Status Quo
While two directly impacted property owners have recently raised concerns about the
high hazard zone, the regulation continues to serve overall city objectives. No substantial
changes in objectives, technology or methodology have been identified that form a clear
basis to pursue amendments to the ordinance at this time. The city has a significant
backlog of floodplain management-related projects and maintaining the existing
ordinance would allow staff, the WRAB, and City Council to continue to focus on those
previously identified priorities.
Option 2 - Evaluate Post-flood Compensation
This option would involve a targeted evaluation of the current regulation's post-flood
property acquisition mechanism. This option could help to resolve or reduce the concerns
raised about how that provision might be applied. Regardless of the specific ordinance
language, it would be difficult to remove all uncertainty from the provision. While the
ordinance establishes the city's intent, the extent of flood damage, availability of funding,
and legal considerations may be greater determining factors than the ordinance language.
The current funding level for post-flood property acquisition would most likely not be
sufficient for a major flood event impacting multiple properties.
At a minimum, any ordinance change would require consideration by the WRAB,
Planning Board and City Council. Staff anticipates that this effort would take
AGENDA ITEM # VII PAGE-6-
approximately one year to complete and would recommend that initiation be deferred
until at least the third quarter of 2013 to allow for completion of the critical facilities and
mobile populations ordinance project. Other projects would likely need to be deferred to
accommodate the addition of this work program item.
Option 3 - Evaluate Entire Regulation Option
This option would involve a comprehensive reevaluation of the high hazard zone
concept. It is anticipated that this would involve a multi-year technical analysis and
public process. In the event that a new methodology was adopted, it is anticipated that an
additional multi-year process would be required to update city mapping. This effort
would require deferral of a significant number of floodplain mitigation efforts. As with
Option 2, staff would recommend that initiation of a project be deferred until at least the
third quarter of 2013 to allow for completion of the critical facilities and mobile
populations project.
ATTACHMENTS:
Attachment A: Boulder Revised Code Floodplain and High Hazard Zone Regulations
(9-3-2 and 9-3-5)
Attachment B: 1989 City Council Study Session Memo
Attachment C: Love and Associates High Hazard Zone Analysis
Attachment D: CSU Peer Review and Product Number Verification Study
AGENDA ITEM # VII PAGE-7-
Information Item
on
High Hazard Zone Regulations
Op gpJ' 1
Floodplain Reg. Overview }
l
a 100-Year Floodplaln
h,
Conveyance Zone
_ " sue`',
High Hazard Zone
High Hazard Zone - History
usf
l~J
4
Address life
safety risks
,.r,, , as iwF
G
Restrict unsafe
development
a_..:.f tiL-' n T. n a~
t
Implementation of HHZ
•
Creek Habitable Buildings in
High Hazard Zone
Bear Canyon Creek 2
Bluebell Creek 2
Boulder Creek 31
Fourmile Canyon Creek 9
Goose Creek 44
Gregory Canyon Creek 26
Kings Gulch 1
Skunk Creek 22
South Boulder Creek 4
Sunshine Canyon Creek 4
Twomile Canyon Creek 22
Wonderland Creek 13
Total 180
134 structures removed through:
• Preflood acquisition 4
• Constructed improvements
r
Peer Community Regulations
CAyo City of
Flirt ollins1,~ i MADISON
1 ~ 1 + L
Boulder County . I
Colorado
5
Restrictions on Structures
a
- , ` P4
A
Post Flood Property Acquisition
W- ME60M Flood insurance for
POAL FLOQO property damage
City money set
aside to buy land
7
Questions and Comments A. 9:
41
J 8