6A - Flood protection levee reconstruction and improvements along Bear Canyon Creek - Community and Environmental Assessment Process (CEAP)
CITY OF BOULDER
INFORMATION ITEM FOR:
TRANSPORTATION ADVISORY BOARD
WATER RESOURCES ADVISORY BOARD
PLANNING BOARD
PARKS AND RECREATION ADVISORY BOARD
OPEN SPACE BOARD OF TRUSTEES
ENVIRONMENTAL ADVISORY BOARD
GREENWAYS ADVISORY COMMITTEE AGENDA ITEM
WATER RESOURCES ADVISORY BOARD AGENDA ITEM
MEETING DATE: May 2002
SUBJECT:
Community and Environmental Assessment Process (CEAP)
Flood Protection Levee Reconstruction and Improvements
Bear Canon Creek - Foothills Parkwa to Arapahoe Avenue
REQUESTING DEPARTMENT:
Public Works Department - Utilities Division
Ned Williams, Assistant Director of Public Works for Utilities
Bob Harberg, Utilities Projects Coordinator
Anne Noble, Greenways Coordinator
Nancy Steinber, er, Engineering Project Manager
BOARD ACTION REQUESTED:
Staff requests board members to review and provide comments on the CEAP, and requests the
Water Resources Advisory Board (WRAB) and the Greenways Advisory Committee (GAC) to
consider a roval of the CEAP at their meetings in May 2002.
Purpose:
Information Item and Agenda Item for WRAB and GAC
Staff is requesting board members to review the CEAP and provide comments to your
Greenways Advisory Committee representative or Nancy Steinberger at (303) 441-4111. The
Water Resources Advisory Board and the Greenways Advisory Committee meetings in May
2002 will include public hearings and consideration of the CEAP for approval.
Background
The proposed project involves reconstructing and improving the existing flood protection levee
along Bear Canyon Creek between Foothills Parkway and Arapahoe Avenue. Components of the
project include extending the length of the levee to increase the capture of flood waters, raising
the height of the levee to meet the current FEMA standards for freeboard, planting the levee with
native grasses and shrubs, selective debris removal from the stream channel, water quality BMPs,
environmental restoration, and habitat preservation of the stream corridor. A future phase of this
project may include excavation within the west overbank (in the grassy area between Foothills
Parkway and the Open Space property) to increase flood conveyance.
The center segment of the levee, which parallels the north-south stretch of Harrison Avenue, will
be improved by adding structural backfill and riprap covered by topsoil to increase the height and
will have a 3-foot top width to accommodate a footpath. The segments at the upstream and
downstream ends of the levee will use a structural concrete flood wall in combination with a
riprap levee covered by topsoil. Selective debris thinning and environmental enhancements will
be coordinated with city Open Space staff. The levee project is located along Bear Canyon Creek
between Foothills Parkway and Arapahoe Avenue, although environmental enhancements may
extend upstream of Foothills Parkway.
Analysis:
Critical deficiencies have been identified in the existing flood protection levee for the
Willowridge Park Subdivision, located along Harrison Avenue immediately east of Bear Canyon
Creek. During a recently updated study of the Bear Canyon Creek floodplain, prepared by Love
and Associates, Inc. under a city of Boulder contract, the existing levee was found to be out of
compliance with current FEMA standards for freeboard. The levee was also found to have
vulnerabilities to flooding which include low crest elevations subject to possible overtopping and
inadequate length subject to possible flooding around the upstream and downstream ends.
Due to these identified deficiencies, the consultant was obliged to omit the flood protection levee
from the updated floodplain study. As a result, the Bear Canyon Creek floodplain in this area
without the flood protection levee would be significantly increased and would adversely impact
as many as 42 residential structures containing 58 separate dwelling units. Without the levee the
conveyance zone spreads to the northeast, impacting the Willowridge neighborhood and the
Boulder Community Hospital site. The purpose of the proposed project is to reconstruct and
improve the existing levee to function more effectively, to meet current FEMA standards and to
provide environmental enhancements of the stream corridor.
This project was included in the 2002 CIP for the Flood Utility and the Greenways Program, and
was referenced in the Annexation Agreement for the Boulder Community Hospital development
approved by City Council. The Open Space Board of Trustees has approved the disposition of
approximately 22,000 square feet of the Hatch Open Space property for the purpose of
reconstructing, improving, and maintaining the flood protection levee.
Action Requested:
Staff requests board members to review and provide comments on the CEAP and requests the
Water Resources Advisory Board and the Greenways Advisory Committee to consider approval
of the CEAP for the flood protection levee reconstruction and improvements for Bear Canyon
Creek between Foothills Parkway and Arapahoe Avenue.
Attachment: Community and Environmental Assessment Process (CEAP)
Flood Protection Levee Reconstruction and Improvements
Bear Canyon Creek - Foothills Parkway to Arapahoe Avenue
COMMUNITY AND ENVIRONMENTAL ASSESSMENT PROCESS
Flood Protection Levee Reconstruction and Improvements
Bear Canyon Creek - Foothills Parkway to Arapahoe Avenue
April 11, 2002
1. Description and location of the project:
The proposed project involves reconstructing and improving the existing flood protection levee
along Bear Canyon Creek between Foothills Parkway and Arapahoe Avenue. Components of the
project include extending the length of the levee to increase the capture of flood waters, raising
the height of the levee to meet the current FEMA standards for freeboard, planting the levee with
native grasses and shrubs, selective debris removal from the stream channel, water quality Best
Management Practices (BMPs), environmental restoration, and habitat preservation of the stream
corridor. A future phase of this project may include excavation within the west overbank (in the
grassy area between Foothills Parkway and the Open Space property) to increase flood
conveyance.
The center segment of the levee, which parallels the north-south stretch of Harrison Avenue, will
be improved by adding structural backfill and riprap covered by topsoil to increase the height,
and will have a 3-foot top width to accommodate a footpath. The segments at the upstream and
downstream ends of the levee will use a structural concrete flood wall in combination with a
riprap levee covered by topsoil. Selective debris thinning and environmental enhancements will
be coordinated with city Open Space staff. The levee project is located along Bear Canyon Creek
between Foothills Parkway and Arapahoe Avenue, although environmental enhancements may
extend upstream of Foothills Parkway (see Vicinity Map).
2. Background, purpose and need for the project:
Critical deficiencies have been identified in the existing flood protection levee for the
Willowridge Park Subdivision, located along Harrison Avenue immediately east of Bear Canyon
Creek. During a recently updated study of the Bear Canyon Creek floodplain, prepared by Love
and Associates, Inc. under a city of Boulder contract, the existing levee was found to be out of
compliance with current FEMA standards for freeboard. The levee was also found to have
vulnerabilities to flooding which include low crest elevations subject to possible overtopping and
inadequate length subject to possible flooding around the upstream and downstream ends.
Due to these identified deficiencies, the consultant was obliged to omit the flood protection levee
from the updated floodplain study. As a result, the Bear Canyon Creek floodplain in this area
1
without the flood protection levee would be significantly increased and would adversely impact
as many as 42 residential structures containing 58 separate dwelling units. Without the levee the
conveyance zone spreads to the northeast, impacting the Willowridge neighborhood and the
Boulder Community Hospital site. The purpose of the proposed project is to reconstruct and
improve the existing levee to function more effectively, to meet current FEMA standards and to
provide environmental enhancements of the stream corridor.
The existing flood protection levee was constructed in 1977 as part of the Willowridge Park
Subdivision development. A floodplain development permit was issued May 5, 1977, to
"construct a structure in the Floodway to prevent Bear Canyon Creek flood flow from entering
Willowridge Subdivision" and was generally described as a flood protection dike. Additional
staff correspondence pertaining to the 1977 permit also indicated that construction of the 47th
Street - Foothills Highway "should require that the complete highway plan include excavation of
a 100-year capacity channel... adjacent to the highway." Subsequent highway construction
completed in 1979 did not include the recommended drainageway improvements, leaving the
Harrison Avenue berm as the only flood protection for the Willowridge neighborhood. A future
phase of the currently proposed project may include excavation within the west overbank (in the
grassy area between Foothills Parkway and the Open Space property) to increase flood
conveyance. Although levees are not currently regarded as the most progressive floodplain
management approach, this technique avoids impacts to the stream corridor that would result
from increasing the conveyance of the creek. In addition, the existing levee is included on the
adopted Flood Insurance Rate Map (FIRM) but has critical deficiencies, therefore repairs are
needed.
This project was included in the 2002 CIP for the Flood Utility and the Greenways Program, and
was referenced in the Annexation Agreement for the Boulder Community Hospital development
approved by City Council. The Open Space Board of Trustees has approved the disposition of
approximately 22,000 square feet of the Hatch Open Space property for the purpose of
reconstructing, improving, and maintaining the flood protection levee.
3. Description of project alternatives and summary of major issues:
Three alternatives were evaluated for addressing the deficiencies in the existing flood protection
levee. These included:
a) Re-map the floodplain omitting the existing levee.
This was rejected for several reasons. First, omitting the existing levee is a modeling
scenario, not a physical reality, since the current berm does exist although it does not meet
the standards of a flood protection levee. Second, in the model that omits the levee, the
conveyance zone spreads to the northeast, impacting the Willowridge neighborhood and the
Boulder Community Hospital site. The existing berm would impede this conveyance zone
shift to some degree, and the actual conveyance zone would depend on the location of berm
2
failure. Third, as many as 42 residential structures containing 58 separate dwelling units
would enter the Special Hazard Area on the FIRM.
b) Excavate the Bear Canyon Creek channel to increase the capacity of the drainageway.
This was rejected due to the environmental impacts associated with channelization,
recognizing that the majority of the impacts would occur on city of Boulder Open Space
property. Modified components of this alternative were incorporated into the proposed
project. Selective debris removal is being proposed as part of the project to improve habitat
value and reduce blockage of the stream channel. Excavation within the west overbank (in
the grassy area between Foothills Parkway and the Open Space property) may be considered
as a future phase of the project to increase flood conveyance capacity.
c) Reconstruct and improve the existing flood protection levee.
This is the selected alternative. The proposed project will meet the objective of providing
flood protection for the Willowridge neighborhood and prevent the shift in the conveyance
zone which would impact the neighborhood and the Boulder Community Hospital site.
Although levees are not currently regarded as the most progressive floodplain management
approach, this technique avoids impacts to the stream corridor that would result from
increasing the conveyance of the creek. In addition, the existing levee is included on the
adopted FIRM but has critical deficiencies; therefore, repairs are needed. Components of the
project include extending the length of the levee to increase the capture of flood waters,
raising the height of the levee to meet the current FEMA standards for freeboard, planting the
levee with native grasses and shrubs, selective debris removal from the stream channel, water
quality BMPs, environmental restoration, and habitat preservation of the stream corridor. A
future phase of this project may include excavation within the west overbank (in the grassy
area between Foothills Parkway and the Open Space property) to increase flood conveyance.
4. Public input to date:
There has been public input on the CIP, the Boulder Community Hospital site development, and
the disposition of the Open Space land for the reconstruction, improvement and maintenance of
the levee. In addition, the neighbors are being asked for input regarding the final design,
alignment, and the landscaping of the levee at a neighborhood meeting on April 18, 2002.
5. Staff project manager:
The Engineering Project Manager for this project is Nancy Steinberger.
6. Other consultants or relevant contacts:
The consultant on this project is:
Drexel, Bartell and Company - civil engineering, hydraulic modeling, levee design
3
Goals Assessment:
1. Using the BVCP, describe the primary city goals that the project will help to
achieve:
General
The goal of the project is to mitigate flooding by reconstructing and improving the
existing flood protection levee along Bear Canyon Creek to function more effectively, to
meet current FEMA standards and to provide environmental enhancements of the stream
corridor.
Community Design
The levee is not proposed to be a community design feature. There will be improvements
made to the landscaping by using native species in the revegetation plan, and the
environmental enhancements will contribute to community design goals.
Facilities and Services
The proposed project improves an existing flood control facility and includes
environmental enhancement of the stream corridor.
Environment
The project will include environmental enhancement of the Bear Canyon Creek corridor
in the project area. Specific improvements include planting the levee with native grasses
and shrubs, selective debris removal from the stream channel, water quality BMPs,
environmental restoration, and habitat preservation.
Economy
The project will provide flood mitigation to protect residential and commercial properties,
and will prevent the shift in the conveyance zone which would impact the Boulder
Community Hospital site.
Transportation
The proposed project will not effect transportation. The reconstructed levee will include
a 3-foot top width to accommodate a footpath.
Housing
The project will provide flood mitigation to protect existing residential structures.
Social Concerns and Human Services
The project will prevent the shift in the conveyance zone which would impact the
4
Boulder Community Hospital site.
2. What are the trade-offs in terms of city policies and goals?
Current floodplain policies embrace non-structural approaches to floodplain management which
accommodate floods but do not attempt to control or contain them. Although levees are not
currently regarded as the most progressive floodplain management approach, this technique
avoids impacts to the stream corridor that would result from increasing the conveyance of the
creek. In addition, the existing levee is included on the adopted FIRM but has critical
deficiencies; therefore, repairs are needed. The project goal is to reconstruct and improve the
existing levee to function more effectively and to meet current FEMA standards, and to provide
environmental enhancements of the stream corridor.
3. Is this project referenced in a master plan? If so, what is the context in terms of
goals, objectives, larger system plans, etc.? If not, why not?
This project is referenced in the Greenways Master Plan. In terms of goals, objectives and larger
system plans, this project meets multiple objectives of the Greenways Program including
stormwater and flood mitigation, habitat preservation and water quality enhancement.
4. How will the project exceed city, state, or federal standards and regulations?
The project will meet or exceed all standards and regulations. In particular, the project will
reconstruct and improve the existing levee which is included on the adopted FIRM but has
critical deficiencies. The project goal is to reconstruct and improve the existing levee to function
more effectively, to meet current FEMA standards and to provide environmental enhancements
of the stream corridor.
Impact Assessment
1. Using the attached checklist, identify the potential impacts of the proposed project
or (if applicable) the project alternatives:
5
COMMUNITY AND ENVIRONMENTAL ASSESSMENT PROCESS - CHECKLIST
Flood Protection Levee Reconstruction and Improvements
Bear Canyon Creek- Foothills Parkway to Arapahoe Avenue
Note: The following questions are a supplement to the CEAP checklist. Only those questions
indicated on the checklist are answered in full.
A. Natural Areas
1. Describe the potential for disturbance to or loss of significant: species, plant
communities, wildlife habitats, or ecosystems via any of the activities listed
below. (Significant species include any species listed or proposed to be listed as
rare, threatened or endangered on federal, state, county lists.) - SEE BELOW
a. construction activities
b. vegetation removal
c. human or domestic animal encroachment
d. chemical pollutants (including fertilizers, pesticides, herbicides)
e. behavioral displacement of wildlife species (due to noise from use
activities)
f. introduction of non-native plant species in the site landscaping
g. hydrologic alteration (groundwater, surface runoff)
h. increased sedimentation in any body of water
If potential impacts have been identified, please provide the following:
• A description of how the proposed project would avoid, minimize, or mitigate
identified impacts. - SEE BELOW
• A habitat assessment of the site, including: 1. a list of plant and animal species
and plant communities of special concern found on the site; 2. a wildlife habitat
evaluation of the site. - SEE BELOW
• Maps of the site showing the location of any Boulder Valley Natural Ecosystem,
Boulder County Environmental Conservation Area, or critical wildlife habitat. -
NOT APPLICABLE
a. The project involves construction activities on the existing levee, which is located 40-feet to
200-feet east of the stream channel. Heavy equipment will be used, although the noises and
potential disturbance will be similar to that associated with traffic on nearby Foothills
6
Parkway. Potential is low for disturbance to or loss of significant species, plant communities,
wildlife habitats, or ecosystems via construction activities.
b. Some vegetation, including trees, will be removed to accommodate the levee reconstruction
and improvements. Non-natives, primarily crack willow, will be removed, while native trees
and shrubs will be avoided to the extent practical. The levee will be replanted with native
grasses and shrubs.
c. It is not expected that disturbance from humans and domestic animals will increase as a result
of the project.
d. Chemical pollutants will not be part of the project. Maintenance of the vegetation after
project completion will be performed by selective mechanical removal of noxious weeds,
with limited use of herbicides. If herbicides are selected for control, only chemicals certified
for use near streams will be used.
e. Due to the location of the project near Foothills Parkway and residential yards, it is likely that
the resident species include tolerant urban generalists which are not sensitive to noise or other
human disturbances. Therefore the potential is low for behavioral displacement of wildlife
species.
f. Only native vegetation will be used in site landscaping.
g. Hydrologic alteration will be part of the project, since the primary purpose is to mitigate
flooding.
h. Sedimentation will not be increased. Selective debris removal from the stream channel and
water quality BMPs will reduce sedimentation to the stream.
B. Riparian areas/floodplains
1. Describe the extent to which the project will encroach upon the 100-year,
conveyance or high hazard flood zones. - SEE BELOW
2. Describe the extent to which the project will encroach upon, disturb, or fragment a
riparian corridor. - SEE BELOW
If potential impacts have been identified, please provide the following:
• A description of how the proposed project would avoid, minimize, or mitigate
identified impacts. - SEE BELOW
• A map showing the location of any streams, ditches and other water bodies on or
near the project site. - SEE ATTACHED
• A map showing the location of the 100-year flood, conveyance, and high hazard
flood zones relative to the project site. - SEE ATTACHED
7
The proposed project lies primarily within the 100-year floodplain, but also encroaches into the
high hazard and conveyance zones of Bear Canyon Creek. The purpose of the project is to
provide flood mitigation by reconstructing and improving the existing levee to function more
effectively, to meet current FEMA standards and to provide environmental enhancements of the
stream corridor.
This project is within the riparian corridor for Bear Canyon Creek, and is partially located on city
of Boulder Open Space property. A Greenways Riparian Habitat Assessment was conducted
during the summer of 1999. This assessment evaluated the quality of riparian habitat along
Boulder Creek and all of its tributaries through the city of Boulder, including Bear Canyon
Creek. Ratings were determined for the structure of the vegetation, the amount of native
vegetative species and the variety of bird species present. This project encompasses BCC Reach
1 of the Riparian Habitat Assessment. In this reach the ranking for native plant species was poor,
but the vegetative structure ranking was good. The aquatic habitat ranking was fair. No data was
reported for this reach for bird species richness. This project will not compromise the quality of
the riparian habitat and in fact may improve the stream corridor by planting the levee with native
grasses and shrubs, selective debris removal from the stream channel, water quality BMPs,
environmental restoration, and habitat preservation. In addition, the levee may provide a barrier
to separate the riparian habitat from the roadway and adjacent residential uses.
C. Wetlands
1. Describe any disturbance to or loss of a wetland on site which will result from the
project. - SEE BELOW
If potential impacts have been identified, please provide the following:
• A description of how the proposed project would avoid, minimize, or mitigate
identified impacts. - SEE BELOW
• A map showing the location of any wetlands on or near the site. Identify both
those wetlands which are jurisdictional under city code (on the wetlands map in
our ordinance) and other wetlands pursuant to federal criteria (definitional). - SEE
ATTACHED
The proposed project is primarily within the wetland buffer, but will encroach into city of
Boulder regulatory wetland No. 7 due to the lengthening of the levee to the south and the
environmental enhancements. The quality of the existing wetland area is medium, as it contains
some of the only forested wetlands along Bear Canyon Creek in the city. One of the goals of the
proposed project is to improve wildlife habitat and water quality. Impacts to wetlands will be
avoided where possible and minimized in areas where impacts are unavoidable. The mitigation
efforts will be on-site and in-kind, and will meet or exceed the city's regulatory requirement of
8
2:1. The project also serves as a restoration effort, therefore considerable effort will be devoted
to removing non-native vegetation, native plantings, and improvement of the functioning of the
wetland and riparian area as wildlife habitat.
D. Geology and soils
1. Describe any:
a. impacts to unique geologic or physical features
b. geologic development constraints or effects to earth conditions or
landslide, erosion, or subsidence
c. substantial changes in topography
which will result from the project. - SEE BELOW
The project will not impact any geologic or physical features except for the extension of the levee
and the increase in levee height.
E. Water Quality
1. Describe potential impacts to groundwater or stormwater quality which may result
from the project. - No IMPACTS
2. Describe potential increases in stormwater discharges which may result from the
project. - No IMPACTS
3. Describe potential water quality impacts to streams, ditches and other water
bodies from the project. - No IMPACTS
4. Is there a likelihood of groundwater contamination from past history on the site or
an adjacent site? - No IMPACTS
The completed project will improve water quality by including environmental enhancements
such as selective debris removal from the channel and water quality BMPs.
Stormwater conveyance will be improved by providing flood mitigation. There will be no
additional impervious area as a result of the project.
Construction activities near stream channels have the potential to impact water quality. Best
Management Practices (City of Boulder Wetlands Guidelines) will be followed to minimize
impacts.
9
No contaminated groundwater impacts have been identified at the site.
Air Quality
1. Describe potential impacts to air quality resulting from this project. Distinguish
between impacts from mobile sources (VMT/trips) and stationary sources (APEN,
HAPS). - No IMPACTS
The project will not have any impact on air quality.
G. Resource Conservation
1. Describe potential changes in water use which may result from the project. - No
IMPACTS
a. Estimate the indoor, outdoor (irrigation) and total daily water use for the
facility.
b. Describe plans for minimizing water use on the site.
2. Describe potential increases in energy use which may result from the project. -
No IMPACTS
a. Describe plans for minimizing energy use on the project or how energy
conservation measures will be incorporated into the building design.
3. Describe the potential for excess waste generation resulting from the project.
Describe plans for recycling and waste minimization (deconstruction, reuse,
recycling, green points). - No IMPACTS
The project will not use water or energy, or generate waste. Initially, plantings will need to be
watered to ensure establishment and survival. Plantings will be selected and located based on the
water requirements of the plant and the site conditions to minimize the need for continued
watering.
H. Cultural/Historic Resources
1. Describe any impacts to:
a. a prehistoric or historic archaeological site.
b. a building or structure over fifty years of age.
C. a historic feature of the site such as an irrigation ditch.
10
d. significant agricultural lands.
which may result from the project. - No IMPACTS
The project will not impact any cultural or historic resources. Two abandoned concrete irrigation
features exist east of Foothills Parkway, north of the current Wellman Ditch. The project will
avoid these structures.
1. Visual Quality
1. Describe any effects on:
a. Scenic vistas or views open to the public.
b. The aesthetics of a site open to public view.
C. View corridors from the site to unique geologic or physical features.
which may result from the project. - SEE BELOW
The project will increase the height of the existing flood protection levee, therefore there may be
a small impact on scenic views or view corridors. The view from the footpath on top of the levee
will improve as a result of the increase in levee height. The aesthetics of the site will be
considered during final design to minimize impacts.
J. Safety
1. Describe any additional health hazards, odors, or exposure of people to radon that
may result from the project. - No IMPACTS
2. Describe any additional site hazards that may result from the project. (Including
risk of explosion or the release of hazardous substances such as oil, pesticides,
chemicals or radiation) - No IMPACTS
The proposed project will improve safety by providing flood mitigation. There will be no
additional health hazards, odors, exposure to radon, or increased site hazards as a result of the
project.
K. Physiological Well-being
1. Describe the potential for exposure of people to excessive noise caused by any
phase of the project. - SEE BELOW
11
2. Describe any excessive light or glare that may result from the project. - No
IMPACTS
3. Describe any increase in vibrations that may result from the project. -No
IMPACTS
If potential impacts have been identified, please provide the following:
• A description of how the proposed project would avoid, minimize, or mitigate
identified impacts. - SEE BELOW
During construction, noise related to heavy equipment operation will be generated during the
daytime hours. No other phase of the project will have a negative impact on physiologic well
being.
L. Services
1. Describe any additional need for the following services as a result of the project: -
No IMPACTS
a. health care/social services
b. water or sanitary sewer services
c. police services
d. fire protection
e. recreation or parks facilities
f. libraries
g. transportation improvements/traffic mitigation
h. parking
i. affordable housing
j. open space/urban open land
k. power or energy use
1. telecommunications
The proposed project will not increase the need for any of the above services or facilities.
2. Describe any impacts to any of the above existing or planned city services or
department master plans as a result of this project. (e.g. budget, available parking,
planned use of the site, public access, automobile/pedestrian conflicts, views) -
No IMPACTS
There will be no impacts to any of the above existing or planned city services or department
master plans as a result of this project.
12
M. Special Populations
1. Describe any effects the project may have on the following special populations:
- No IMPACTS
a. persons with disabilities
b. senior population
c. children
d. restricted income persons
There will be no impacts to special populations as a result of this project.
13
Community and Environmental Assessment Process Checklist
Project title: Flood Protection Levee Reconstruction and Improvements
A
A
M
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E
A. Natural Areas
1. Disturbance to species, communities, habitat, ecosystems? Y N Y
B. Riparian AreasfFloodplains
1. Encroachment upon the 100-year, conveyance or high hazard flood zones? Y N Y
2. Disturbance to or fragmentation of a riparian corridor? Y N Y
C. Wetlands
1. Disturbance to or loss of a wetland on site? Y N Y
D. Geology and Soils
1.a. Impacts to unique geologic or physical features? N N Y
b. Geologic development constraints? N N N
c. Substantial changes in topography? N N Y
E. Water Quality
1. Impacts to groundwater or stormwater quality? N N N
2. Discharges to the stormwater or sanitary sewer system? N N N
3. Potential impacts to streams, ditches, or other water bodies? N N Y
4. Groundwater contamination on site? N N N
F. Air Quality
1. Impacts to air quality? N N N
G. Resource Conservation
1. Changes in water use? N N N
2. Increases in energy use? N N N
3. Generation of excess waste? N N N
H. Cultural/Historic Resources
1.a. Impacts to a prehistoric or archaeological site? N N N
b. Impacts to a building or structure over fifty years of age? N N N
c. Impacts to a historic feature of the site? N N N
d. Impacts to significant agricultural land? N N N
1. Visual Quality 1.a. Effects on scenic vistas or public views? N N N
Y = Applicable
Page 1 N = Not Applicable
Community and Environmental Assessment Process Checklist
b. Effects on the aesthetics of a site open to public view? N N N
c. Effects on views to unique eolo is or physical features? N N N
J. Safety
1. Health hazards, odors, or radon? N N N
2. Site hazards? N N N
K. Physiological Well-be
1. Exposure to excessive noise? N N N
2. Excessive light or glare? N N N
3. Increase in vibrations? N N N
L. Services
1. Additional need for:
a. health care/social services? N N N
b. sanitary _sewer services? N N N
c. police services? N N N
d. fire protection? N N N
e. recreation or parks facilities? N N N
f. libraries? N N N
g. transportation improvements/traffic mitigation? N N N
h. parking? - N N N
L affordable housing? N N N
j. open space/urban open land? N N N
k. power or energy use? N N N
1. telecommunications? N N N
M. Special Populations
1. Effects on:
a. persons with disabilities? N N N
b. senior population? N N N
c. children? N N N
d. restricted income persons? N N N
Y = Applicable
Page 2 N = Not Applicable
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~ rC
E UR913AAl
LEGEND
500 0 500 Feet
`-F High haz.shp MepLink
Conveyshp City of Boulder GIs
100year.shp N
f
o~
Wetlands Map
- -
s'
it
a a I o.
- I lp c;
a
Lev f ~FTM 14 r
s
SITE E F ~~a Q
- \ r D
1
LAU
UZI
film
pw~ p LEGEND
Buddm FF ~
r.k 500 0 500 Feet
I/i\\1 MapLink
City of Boulder GIB
Tj~if sumred.~ati poViledu ~apticil mpreeemuirm mdy
]Le CnyofBwlder m
o~PrH~ N
~cn 2 el=nd.
omm~yrn
3 w
3
11" LAYER OF D5o-6" RIPRAP
OVER 12" TYPE R BEDDING. \i~\ \
COVER RIPRAP WITH 4" OF
NATIVE TOP SOIL AND SEED O \\/~\\i\~
WITH NATIVE SEED MIX. Q :<I
~O EXISTING GROUND
~jA / / 0 . / SELECT BACKFILL APPROVED BY
GEOTECHLAICAL NICAL ENGINEER. COMPACTED
T /\/,,Q OQ~ TO 95% STANDARD PROCTOR.
t6"
LEVEE IMPROVEMENT - TYPE A
NO SCALE
I
10
#4 0 18" D.C. 'y
r
N
PROPOSED GRADE-SEE PLAN
0 \ \ PROPOSED GRADE-SEE PLAN
5 0 18" O.C. /
_~CONCRETE DD
\ N
11" LAYER OF D55=6" RIPRAP Q Q " FLOOD WALL
OVER 12" TYPE II BEDDING.
COVER RIPRAP WITH 4" OF
NATIVE TOP SOIL AND SEED
MATH NATIVE SEED MIX. 10" 10"
TOP OF FOOTER ~
2 J4
T~\/VO~VO o_
oO O r _ SELECT BACKFlLL\\ QQ Q ° APPROVED BY
N GEOTECHNICAL ENGINEER.
COMPACTED TO 95%
SELECT BACKFlLL
APPROVED BY STANDARD PROCTOR.
GEOTECHNICAL ENGINEER.
COMPACTED TO 95% BOTTOM OF FOOTER
STANDARD PROCTOR.
14" 10" 61.
18"
LEVEE IMPROVEMENT - TYPE B
NO SCALE
k JX I 5246.5 ` 5244.8
5253.0 ti I J •J
I
J 5243.4
5247. 246.2 5245.5 5242.9 5240.8 5~ 5~ 11
sku EE : 520240.6 Regulatory Flood Map
5239.(
s E f d L SEES ET A 0
REVISI S T /S ~ ~3~
c~ fE ' 5233.
K 5244.6 REQ. CONFLU NC \ 3
41.4 \ 5241.1 SkUNk CR 1 5237.5
3 e She 5244.9 ` 2 95 3 5236,
5240.6 239.752 .8 X5236.4
?7L0 S~SO 3 5246.4 5243.0 5241.0 Q 5239.7
ago 25 35.2 3 35 6 52351
5 6.5 BOULDER CR K 5h 6 5 ` 5239.2 39.0 236.9 w/
5267.2 5260.7 ! 5245ELDLA/)V W
2 4
5240.5 ~ 5237. ~
5244.6 ` r• 523 .
5232
5259.1
6.2 92 ~ p32
5241.7 37 1 fisting &A '*emolit~ .4
l _ : • ~ q Structarea From -
3 ~ 5236.7 S
rh1 /00
of -~'R
52 .6 . : r 5235.4
High Hazard Zone ~i 5 R oo p/a/s
`s 5938.8 _ 523 0 5231
(5,625262. 2.2.4 Conveyance Zo ~ b241.0 5232.5
/J ~\w 5250'
5 ~ do 0 1~ 7.4
q...
' 1 52 4:
!t523 4
5250.4 S. 5:"' ~ 5238.
3% O D e ns Trees
5~ 3 8~ Fort 1 O
5232.3
\ 5263.6 0 ( 42.2 ) C) ; 5231.1
03
524 .8 nN 4f2 "
1 52 1.7p
26 5251.1 C6 x
/ D xlr 1133 n ~j 37.3 5234.6
CZ 7~,
I~ D m"' 524b-A V524 .I 5 5233.1 5
.4 \I 25 8 52U3q74.
3 ~ 5 2 7. 2
1156. U v 5 42 235.
5 2 6.3
267.5 s2$
/ 5262. 23 .I 22
/ 5259.0 260 0/ 0- YEAR SHALLOW FLOODING AREA
N 1034.59 ft D
.54,283.36ft (Depth = I
E~EV.5 63.42ft
1 .100-Year Floodplain 1 THE FLOODPLAIN DELINEATIONS and FLOOD PROFIT
ON THIS SHEET ARE BASED ON FLOODPLAIN DATA
5266.6 ANCOCK un o r; D. VELOPED AS A PART OF THE FLOOD INSURA CE
Ili111111 II H 8 UDY FOR THE CITY OF BOULDERS EXCEPT WHERE N(
- - - - -
.
----P~ AND ROFIL! FROM SECTION
-GO
_ _
f-- BY_ ~TI#IAIG~. A T..}9EE .
f /
Existing Flood Conditions
f 1 ~r (model omits the berm)
t~ 1 r ~ y ~ ~ } X {
It
an W SAM W "Y' 7 of
ZIV
/i i / 17 /ti
1 / ~/i/// i• ii,/ /iii / 'i/
High Hazard Zone / / . ' / . ' ' / / /
10
10
i~
of
016 Id 01
High Hazard Zone
fl
r~ R (j'1
Shallow Flooding 100-Year Floodplain
HANG= DR
r f
® r
O "~,f 1
SrA7E NWr7 TA. 44.75 t' i5 I o. a 2
a I 11263.19 _ I I i +;4.s e _
1 EGIN LEVEE IMPROVEMENTS
O W I NO SEE • FOR LEVEE CROSS-SECTIONS.
TART n nn I \ g Z i PARCEL a [ s.0. SEE LV4 FOR TYPICAL SECTIONS.
AECI NO. U399996'I
Z, ROPOSED VEE I' .
p UGNMENT
~p m r. 1 rasa-
~ta'3 d a r, 1 V- T
MA7FR - - s J I T~52a0.d
F0.5; a t 1 i
_ 'EXTEND EXISTING 2-18' CMP m
CULVERTS19 LF ® 0.5R. PAR L B FILM 313: \ JQ . a
r~. RE
INSk 16" ALUMINUM FLAP 24. a. ..89998 REC. NO. 015150113 T
GATE ENDS OF 18" CMP.
I - I I v ~pC , -
WATERMAN A i 1 OR APPROVED
+62465 I P~
EQUAL I A. 5+39122
I N 9506.16 •,,,-1 !+5240.6
L _ I 1
_
E 12fl67.BD
O
WALL
1404. L
ISTA. 5+
i N 949 D ` - - -
5. 5 ' ti I I - / ul
E 11269.6 iBlGtx C _ `
WILLOWRIOGE PARR,
I LNO
EXTND EXI G 115" PVC
LLLLFFFF u
VERT 00.5S I s'a74+
a. . 2~,. .i"
INSTALL 15' AL MINU Py GATE _
AT END 0 F'15 PVC WATERMAN - - t
WA 76q AF-41 OR P EQUAL` 1 -
FL. 5735.6-
1 Tt1 4 STA 8+A
N 1925184 I / 'T - -
1 rt E 41442.42
p -
' I ADAMS CT s e,7 - 52450
i. l 5~ u r oeaz ~ _--.McK/N!•E~D . _ i
LEVEE TABLE
- +5247
STATION WATER SURFACE TOP OF EXISTING GROUND 1 U / 5257 r
Ft FVATION LEVEE ELEVATION +523?2 / 1\ f _ -
1 e wlu0w15x9E PARK -
1+00 5237.35 5240.35 523&00
1+50 5238.50 5241.50 5237.19 p I llZ FlLwO x0 t
2+00 5239.48 5242.48 5236.60
2+50 5239.91 5242.91 5236.93 i~
3+00 5244.33 5243.33 5236.96 I 5243 I I +sisD
3+50 5240.57 5243.57 5237.24 +524.25' - - f
s `-Bf/RR Gr +5244.2 McK/NtEYDR 32a9ern `
4+00 5240.82 5243.82
5237.49 I - 51534 µ
4+50 5241.06 5244.01 5237.58 I 4524YS
' . - -
5241.31 5244.31 5237.80 1 ' • I _ -
5+00
5+50 5241.60
5244.60
5238.22
6+00 5242.08 5245.08 5238.37 4 3 I I I
-
6+50 5242.57 5245.57 5238.52 I l IIk.
II -
7+00 5243.06 5246.06 523645 I r/ w I
+SR4S9 i
7+50 5243.55 5246.55 5238.95
8+00 5244.03 5247.03 5240.21 0, _
8+50 5244.23 5247.23 5245.10 m
I ICI 15z 2 -
9+00 5244.34 5247.34 5245.15
5244.48 5247.48 5245.36 COOL IAE CT 5__8
9+50
-
10+00 5244.63 5247.63 5245.66
10+50 5244.78 5247.78 5245.86
11+00 5244.93 5247.93 524546 BEAR CANYON CREEK
11+50 5245.32 5248.32 5245.60 CROSS-SECTION
12+00 5245.71 5248.71 5246.15 WuDWR930E PARK I ,r 3_ _
FILING NO 1,
i-525a 12+50 5246.10 5249.10 5246.65 I - -
n
13+50 5246.88 5249988 -EXISTING INDEX CONTOUR
13+00 5246.49 5249.49 5247.62 -
14+00 5247.27 5250.27 _501p _ • • • • - - EXISTING INTERMEDIATE CONTOUR
5248.95
5249.97
.17+
14+50 5247.93 5250.93 5250.75
STA N 817+ 5150 +52573DAL4-AS rri52s2s
15+00 524&85 5251.85 5251.78 mm
=
15+50 5249.77 525277 S E 11423.74
IT FLOODWALL I" G'
16+00 525236 5250.69 5253,69 525250 I 1l1 I - - 100 50 0 100 200
16+50 5251.60 5254.60 525281
17+00 525252 5255.52 5253.79
0'
17+5D 5253.44 5256.44 5253.91 I i l~STA 18450 I
18+00 5254.36 5257.36 5251.90 SCALE: 1"=10 I I .Q N 8258[31
1 n r 5257E 5259
p { 1- Tl,~ E 11440.23--1- -HARR150N AYF -F Pap REC,S
18+50 5255.28 5258.28 5252.69 u- I ~ _ - ~ off ~T qh l
19+00 5255.68 5258.68 5256.73 STA. 19+0 h ^ ` - Zoe ° s~ Fa
1. N 820650
19+50 5256.09 5259.09 5256.19 1 E 11423.74 31659
20+00 5256.49 5259.49 5255.49 I STA 20+00
20+50 5256.89 5259.89 5256.26 N 8116.04
I v yS , +
21+00 5257.29 5260.29 5259.68 I E 1149368 ONaL
STA. 21+29.70
N1118009.311~ ;ZLOWRI 3 PARK _ J
E 11567.45 NOT VALID WITHOUT ORIGINAL
END LEVEE IMPROVEMENTS '0' SIGNATURE AND DATE
END FLOODWALN 1 ! 1t I v -
PREPARED Drexel, Barrel! & CO. Engineers Surveyors PREPARED FOR' RROxcr Nro DESIGNED 4.r REeslox DESCRIPTIONS DAM DRArnNC INFO.
GATE: roe x0.. sHEEr
4840 PEARL EAST CIRCLE, SUITE u4 BOULDER, COLORADO 8030, 1,0,14,2-4.38 BOULDER COMMUNITY HOSPITAL BOULDER COMMUNITY HOSPITAL PRd BEAR CANYON
CREEK 19 DEC 2001
6365 CORPORATE OSUIT COLORA00 SPRINGS, COLORADO 80919 (719) 260-0887 1100 BOULDER, BALSAM COLORADO STREET EAST CAMPUS SITE DRAW BY. pRL LEVEE SCALE:
o JRA'hING NO, SHEETS
CONTACT: JOHN A. EWV, EW-1149 LVt
y
910 54TH AVENUE, SUITE 21p GREELEY, COLORADO 80634 (970) 351-0645 CONTACT.- MINE MONAN (303) 440-2,327 ARAPAHOE AVENUE AT ADO STREET- cxEam Br: H.1
100' 5D 638 EE
7 ` P.E. BOULDER, COLORADO
V. 1 , 100'
- - - - 5250 5250 5250 5265-- - - -
_5255
-ALIGNMENT ALIGNMENT
ALIGNMENT-
TOP OF WALL=5244.31 _
5245 - - 5245 5245 - - - - - - _ -5245 5250 _ 5250
TOP OF BERM=524231 - - - 'TOP OF-BERN=5747:34---
_
_TOP OF WALL=5240.35--__ PROPOSED GRADE
- - _ - - --PROPOSED GRADE
TOP OF FOOTER 5239.64 -
-EXI511NG GROUND
- -
40 EXISTING GROUND- 5240 5245
5246-------- _ -
EXISTING GROUND „ - _ 5240 52 - -
5245
OTTOM OF FOOTER=5237.98
5235 5235 5240 - - - - - 5240
4- _ _OTTOA OF FOOTER=5233§2 -
5230- 10C- 0 10R 5230 5230~ 20C 10L D GR 20R 5230 5235 2
0C 01 0 lOR 20R 5235
5255 -
5250
5250 5255 5255
5255
ALJGNMENT ALIGNMENT---- ~1UGNMENT----,
5245 " - _ - - _ - -TOP OF WALL=524248---- ----5245 5250 5250 5250 TOP OF BERM=5247.83 5250
TOP OF BERM=5240.48 PROPOSED GRADE
TOP OF BERMm524508
PROPOSED GRADE - - - - _
- - - EXISTING GROUND I -
'
5240 ~ _ TOP OF FOOTER 523781 5240 5245 - PROPOSED GRADE _ -5245 5245 - _ _ -5245
- - EXISTING GROUND _ - _ - - - - - - f -
- -
. - _ - - - STING GROUND
- -5240 5Z40
5235 BOTTOM oF_FOOTER 5236.15 ._5240
5230 OL -0 OR - 5230 5235 20L lOL 0 10R 20RR 523 5235" 20( 10L b 10R- 20R 3235
I
~I
5230 5250 255 5255 5255
00 , 5255
CFA=3100 SEA ;71 A-11100
-AT]ONMERT--. - QcrdMEN'r ~iIIGRM tN1
OP-OF-WALL. 5243.33-----
5245 5256 250 5250 TOTrOF`BEItM•5~7:93 5250
-TOP-CIF-BERM=5241 PRDPDSEn GRADE
E~ERM•5746.D
PROPOSEDIGRADE
- _ PROPOSED GRADE EXSRNG GRND
OU
5240E)(ISTING'OROUND-_ _ TOP OF-FO-O-T--E-R-'=--52-3-8-.-66 5240 5245 5245 5245 5245
5240 5240 - 5240,
5235- BOTTOM OF FOOTER=523700-5235.1240- - -
5236 _ 10C 0 10R 5230 5235 20L 0C - R GR _ 2OR 5235 5235- 204 10L 0 - 10R 20R~-_5235
2 50 5250 5255 525 5255 5253
6-rk-4+00 --STA ,8100 -S-TA.-12+00
AIMMEN AIIGNMENT-- AULAMENT- -
TOP OF WALL=5243.82 _ TOP OF BERM=5248.71 _
5245------- - 5245 5250------------I-- - 52 256 - ~"5"230
TOP OF BERM-5241_82 PROPOSED GRADE
OF~ERMa 47.03- - - -
---PROPOSEDiGRADE
PROPOSED GRADE - - RNG-GROUND
5240 EXISTING (GROUND TOP OF FOOTER-5239.15 5240 5245 5245 5245 5245
- EXISTING GROUND(
_PaNRNG/S._.......
- Q, pR NuR F~
5235 - 5235 5240 - 1 -_.52410 5240
3
OTTOM OF FOQTEf3=52
3],.49. 1859
-
5230- 5230 5235 20C lOL 0 1C1R" - 20R 5235 5235 - 20C~ - - -"10L - _R t
NOT VALID WITHOUT ORIGINAL
- - - SIGNATURE AND DATE
PREPAJRED BY: PREPARED FOR: PROJECT INFO: DESIGNED By REVISION OESCRIPTIONS DATE DRAWING INFO. DATE JOB N SHEET
Drexel, Barrell & Co. Engineers SuFIR, 9 BOULDER COMMUNITY HOSPITAL BOULDER COMMUNITY HOSPITAL PRA BEAR CANYON CREEK 19 DEC 2001 EW-1149
LV
\A- 4840 PEARL EAST CIRCLE, SUITE 114 BOULDER COLORADO 803o1 (SO3) 442-4338 1100 BALSAM STREET EQAIH BY
1365 CORPORATE DRIVE COLORADO SPRINGS, COLORADO SD919 719 260-0887 EAST CAMPUS SITE PRJ LEVEE SCALE: DRAING NO.: SHEETS LDER 910 54TH AVENUE.
SATE 210 GREEI£Y, COLORADO 80634 (970) 351-0645 CONTACT. MAKE MOHANL(3030440-2327 ARAPAHOE AVENUE AT 48TH STREET CHECKED By. M i~~=51
CONTACT: JOHN A. EWY, P.E. BOULDER, COLORADO JAE CROSS-SEC11ONS µ 1R=51 510 638 4
.5255 - _ - - - - - - - 5255...5265 - - 5265 5265 5265
.ALIGNMENT_ ___---ALIGNMENT`
TOP OF BERM=5249.49_.__- TOP GF_WALL=5260.29
525D EXISTING GROUND 5260
PROPOSED GRADE 5250 5260 5260 5260
- - ElQSTING-GROUND _TOP OF BERM=525552
PROPOSED GRADE TOP OF FOOTER-5257`62-
- - - - - - STING-GROUND-- -
6245 5255 T 5255 5255 - 8255
- - OTTDM_DF FOOTER=5255.96
5240-_. --5240 5250. 5250 5250
5266
5235 10L b 10R 5235 5245 lOC - 0 - IOR 5245 5245 lOL b 10R 5245
5255 5255 265 5265
- AUGRMENT-`-- -~iIIi,~81ENT--
TOP OF GERM=5250.27_ L
PROPOSED _GRADE
5350` NG-GROUND 5250 5260 OE WALL-525236 526D
r~
_ - - ~F_BERMs525,536-_`
PROPOSEDIGRADE _
EIOSTfNGiG_RDUND _
5245 5245 5255 TOP OF FOOTER=525269 5255
5240 - - - - 5240 525D - - -----BOTTOM OF FOOTER-5251.03 5250
-
5235 10L 0 10R 5235 5245 10L - 0 1oR 5245
5260 --CFA-15th 5260 5265 -3EA.-Y9+00 52x5
________----ALIGNMENT---------'------- - -
ALIGNMENT'----
- - TOP OF 2-68A38
5155' - - - -52_55 52fi0--- - ----5260
TOP OF BERM=5251,85
_ _EXISTING GROUND EXISTING!GROUND TOP OFF FOOTER-5254.01
5250 5250 5255 VBOTTOM OF FOOTER=525.2.35
5245 - -5245 5250 6250
NOR 5240 ,524510L .___._.....____0_._.. _ r NOR --5245,
5260 _ - 526D 52fi5 _ --5265
_ SEA.-16100-- iTA. 20+00--
-..-,---..__ALIGNMENT--- --AUG MENT----
TOP OF WALL=525949-,
- -TOP OF 8
ERM_=$253.80-----
5255- - ----PROPOSED GRADE 5255 5260-- TOP OF BERM_=557.49 5260
PROPOSED 'GRADE
- - - - - - _ EAETING,GROUND - -
2-_
EJpSiING GRWND -TOP OF FOOTER;-5264.8
5250 5250 5255- 5255, a REc
pRTHj,,. ~P
OTfOM OF FOOTER=5253.16
- - - - - - 31659
SSION
- NOT VALID WITHOUT ORIGINAL
- - ZOR 5240 5 SIGNATURE AND DATE
62-40'--- 245
PREPARED BY PREPARED FOR: 1PROZIT INFO. DESIGNED BY. FE`A4ON DESCRIPTIONS DAZE DtAwNG INFO. DAR: JOB N0: SHEE7
- Drexel, Barrell & Co. Engineers Surve)7 BOULDER COMMUNITY HOSPITAL BOULDER COMMUNITY HOSPITAL PRJ BEAR CANYON CREEK 19 DEC 2001 EW-1149
LV
4540 PEARL EAST CIRCLE, SUITE 114 BOULDER, COLORADO 80301 (303) 442-4339 DRAWN BY.
SCARE: ORAwNG N0.: SHEETS
1 365 CORPORATE DRIVE C0.ORADO SPRINGS, COLORADO &1919 (719) 260-0887 1100 BOULDER, BALSAM STRCOLORADOEET EAST CAMPUS SITE PRJ LEVEE
sT0 s H AvENUE score 210 w o GREELEY. COLORADO W634 (920) 351-0645 CONTACT, MIKE MONAN (303) 440-2327 ARAPAHOE AVENUE -AT 48TH STREET CHECKED By. CROSS-SECTIONS
1 _5 5D 638 4
' ROLn my MI ORAnn JAE v: 1"=5~