Partnership for Sustainable
DENVER, COLORADO
South Lincoln Redevelopment Project Stormwater/Green Infrastructure Charrette
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-- FINAL REPORT
/
April 2011
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Prepared Under:
Contract No. EP-W-07-023
Prepared for:
U.S. Environmental Protection Agency
Office of Solid Waste and Emergency Response
Office of Brownfields and Land Revitalization
Washington, DC 20460
Prepared by:
SRA
INTERNATIONAL, INC.
www.sra.com/environment
www.yrgsustainability.com
/S*>**^-
{ISION LAND;
CONSULTANTS. INC
www.visionlandconsultants.com
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Table of Contents
1. Executive Summary 1
1.1. Stormwater and Green Infrastructure Priorities 2
1.2. Summary of Key Findings 2
2. Introduction 4
2.1. Framing the Problem 4
2.2. Charrette Process 5
2.3. Stormwater / Green Infrastructure Charrette Goal 5
3. Stormwater Management Strategy Overview 7
3.1. Site Strategies 8
3.2. Right-of-Way Strategies 10
3.3. Shared Regional Strategies 12
4. Vision Land Analysis and Results 13
4.1. Summary of Analysis 13
4.2. Analysis Conclusions and Recommendations 14
5. Conclusions and Recommendations 16
5.1. Funding and Incentive Opportunities 17
5.2. Strategic Partnerships 17
6. Appendix 18
6.1. Charrette Agenda, Presentation and Handouts 18
6.2. Charrette Photos 18
6.3. Charrette Notes 18
6.4. Charrette Attendees 28
6.5. Acronyms List 29
6.6. Vision Land Report 30
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1. Executive Summary
The Denver Partnership for Sustainable Communities Brownfield Pilot is led by the U.S. Environmental Protection Agency (EPA)
Office of Brownfields and Land Revitalization (OBLR) and the Office of Sustainable Communities (OSC), and is comprised of the
EPA, Department of Housing and Urban Development (HUD), and Department of Transportation (DOT). These agencies are
working together to ensure federal resources and policies support the development of sustainable communities. The partnership
is based on "liability principles" that guide inter-agency collaboration and support the integration of safe, reliable and economical
transportation; affordable, energy-efficient housing; and sustainable reuse of unoccupied or underutilized land. Pilot communities
were selected by EPA's Brownfields Program with input from HUD and DOT, and receive technical assistance and support from
these agencies to build on past investments, identify opportunities to connect housing, transit and brownfields within the
development, and to coordinate resources that can further the integration of sustainability.
The Denver Housing Authority (DHA) is an affordable housing provider whose South Lincoln Redevelopment Project (SoLi) was
selected as a Partnership for Sustainable Communities Pilot in 2010. In recent years, the SoLi project has received much
collaborative support from state, local and community stakeholders and leaders in defining and establishing its concept and goals.
In 2008, prior to being selected as a Pilot project, a 3-acre portion of the SoLi site (at 10th & Osage, included as part of Phase 1 of
the project) received funding from the EPA's Brownfield Cleanup grant program to cleanup the area to unrestricted residential use
cleanup standards. In September 2009, the DHA and key project team members finalized a Master Plan for SoLi focusing on land
use, energy, transportation and public health. In addition, this Master Plan identifies sustainability goals as integral to the project
vision (to view the SoLi Master Plan, go to:
http://www.denverhousing.org/development/SouthLincoln/MasterPlan/Pages/default.aspx).
DHA is committed to making SoLi a successful development that includes progressive stormwater management strategies
addressing both water quality and quantity for storm and surface water. The analysis herein clearly shows that the La Alma /
Lincoln Park stormwater system is not able to manage the 100-year storm, and in some areas the 5-year storm. When the
watershed overflows during a storm event, pollutants drain into Cherry Creek and eventually the South Platte River impacting
water quality. Additionally, the South Platte and Cherry Creek confluence have poor water quality, and stormwater runoff from the
City of Denver only makes this problem worse. Currently, flooding occurs during large storm events at the 10th and Osage light rail
station, the intersections of 13th and Osage and Colfax and Osage, and on the Auraria Campus at 9th and 10th Streets. It will be
important for the City and neighborhood stakeholders to address these issues by improving stormwater quantity and quality,
increasing infrastructure, or a combination of both. It is the goal of DHA to incorporate low-impact design (LID) strategies to
greatly improve these issues, and support best management practices for SoLi and the regional watershed.
Representatives from local, state and federal government agencies, community and resident groups, non-profit and private
sectors participated in an EPA sponsored Stormwater / Green Infrastructure Charrette to identify the current efforts, barriers,
opportunities, and key partners for creating a comprehensive stormwater / green infrastructure solution on the DHA site and for
the Curtis Street Outfall Watershed (the watershed within which SoLi exists). Charrette participants also focused on developing an
implementation plan to increase interagency collaboration on these issues in the regional watershed. As part of the Pilot and
charrette process, technical assistance was provided under contract by SRA International, Inc. and YRG sustainability, as well as
Vision Land Consultants, Inc. and Wenk Associates, Inc. (Technical Assistance Team).
Confluence of the South Platte River and Cherry Creek
Cherry Creek bike path during flooding
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1.1 Stormwater and Green Infrastructure Priorities
The overarching goal of the South Lincoln Stormwater / Green Infrastructure Charrette was to outline a path for developing a
comprehensive regional Stormwater plan for the Curtis Street Outfall Watershed and La Alma / Lincoln Park (LA / LP)
neighborhood that balances the needs and goals of all major developers within and adjacent to the watershed. DMA and Auraria
Higher Education Campus (AHEC) are the two major developers in this watershed. Denver Parks and Recreation (DPR) own a
significant amount of land in the watershed, as well as the Regional Transportation District (RTD) who have light rail stations and
tracks that are impacted by Stormwater overflows at the 10th & Osage light rail station and at Colfax Street and 13th Avenue. In
addition, Denver Public Works (DPW) and Urban Drainage and Flood Control District (UD) are key players in the regional
Stormwater planning and infrastructure implementation.
These major developers and landowners need to coordinate their Stormwater management efforts and investments in order to
achieve a comprehensive regional solution that will minimize development cost, increase functionality and create economies of
scale. However, several major barriers are preventing this from happening. Current Stormwater management efforts focus on
individual site solutions that can be costly and limit site development. It is possible that a shared regional solution will increase the
development potential within the neighborhood while being more cost effective and sustainable in the long term.
CURRENT PRACTICE - INDIVIDUAL SITE SOLUTIONS
WITH WATERSHED MAJOR LANDHOLDERS
GOAL - SHARED REGIONAL SOLUTION
WITH WATERSHED MAJOR LANDHOLDERS
"> .
1*1 - T ^
Curtis Street Outfall Watershed (DHA site highlighted in red)
AHEC DPR DHA
1.2 Summary of Key Findings
The following report is a detailed summary of the discussions, working group sessions, presentations and analysis that occurred
before and during the Stormwater / Green Infrastructure Charrette. The key findings below are a summary and synthesis of the
major issues that were identified during the charrette.
Fund and complete a regional Stormwater engineering study: Analysis completed for the charrette was primarily
site-oriented but did included some evaluation of how LID would impact the Stormwater issues on a regional level.
Although there was a general consensus at the charrette that a shared regional Stormwater solution is probably more
efficient and cost effective, this is not yet proven. A Stormwater engineering study would evaluate the regional
Stormwater impacts and opportunities and build upon the analysis that was completed for the charrette. Neighborhood
stakeholders, who will likely see reduced capital costs with a regional solution, will need to fund or pursue joint grants for
this study. Those same stakeholders will also need to determine the boundaries and scope of the study in order to
address and capture possible opportunities that may be outside of the watershed.
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- Create a convening body that supports inter-agency communication and collaboration: It was clear during the
charrette discussions that there is a real need for a "convener" that can bring together the major developers and land
owners in the watershed to communicate and coordinate efforts and investments. This "convener" will need to be a key
stakeholder in the neighborhood and have decision-making authority over possible regional solutions. The City of
Denver, RTD, and the EPA were three organizations identified as possible "conveners", and it was acknowledged that
participation by Urban Drainage would be crucial. Major stakeholders will likely need an incentive to opt-in to the group
since it will require additional time and effort beyond current practices.
Develop a funding mechanism for shared regional stormwater projects: One of the major barriers charrette
participants identified is that individual developers work with separate budgets and schedules. This makes it very
difficult for developers to collaborate on joint stormwater management solutions. Another challenge is that the city and
federal funding cycles are much shorter than the time required to develop a comprehensive stormwater solution for the
watershed. A funding mechanism needs to be developed that will allow individual developers to both buy into a regional
solution and acquire funding for stormwater solutions that go beyond the requirements of individual projects. This
mechanism will likely need to pay for temporary short-term strategies as well as comprehensive long-term solutions.
Several charrette participants recommended a 20 to 40 year bond to achieve this goal.
- Use the South Lincoln Redevelopment Project to verify effectiveness and operational costs of innovative
stormwater strategies: Some of the more innovative stormwater strategies, such as porous retention basins in the
right-of-way, are considered by some to be risky and unproven in Denver, yet the potential benefits of these strategies is
significant. The Soli project is ideal as a pilot project for various innovative stormwater strategies because DMA has a
strong working relationship with the City of Denver and Phase 1 of the project (1099 Osage) has already incorporated
some of these strategies. (Under the pilot program at 1099 Osage, DMA is responsible for monitoring and maintenance
of these systems). In the long run, the City and its stakeholders will need to determine how to incorporate these designs
into the City standards to ensure adoption by the development community. The City will need to work with the
independent community to determine the best approach to monitoring, maintenance, and overseeing the long-term
improvements to these stormwater strategies. This pilot project would also allow the city to verify the effectiveness of
new stormwater strategies and implement those that are most successful in other watersheds throughout the city.
Implementation of Low-Impact Design (LID) strategies can provide significant benefits to Curtis Street Outfall
Watershed: Low-impact design utilizes decentralized small-scale strategies to manage stormwater. LID strategies are
typically implemented on a site-by-site basis but can manage large stormwater volumes when integrated at a regional
scale. With the right partnerships and approach, SoLi could be an ideal project for showcasing innovative LID strategies
such as rain gardens, vegetated swales and permeable pavements.
Develop shared metrics for success: Each neighborhood stakeholder will have their own goals and needs for a
regional stormwater solution. It will be important for all of the key stakeholders to develop a shared definition of success
that identifies specific goals and metrics. These metrics and goals will likely be influenced by the results of the potential
regional engineering study and the potential strategies identified therein.
All of these recommendations are focused on determining whether a shared regional solution to stormwater management is more
cost effective and efficient than maintaining the current practice of individual site-based solutions. Once this is determined,
neighborhood developers and local regulators can coordinate any viable regional solutions.
Charrette working group sketch
Charrette working group report out
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2. Introduction
The South Lincoln Redevelopment Project is a 17.5 acre development that seeks to revitalize the La Alma / Lincoln Park
community by enabling residents the opportunity to enjoy the unique advantages of a holistic, transit-oriented development
realized through the core attributes established during the design process: a highly green mixed-use community, focused on a
healthy lifestyle, increased non-auto mobility, an integration of resource conservation and management systems, and a diverse
mix of new and existing residents. The redevelopment will include new residential units and a mix of retail, commercial and
community services at the ground floor to encourage and promote activity along the streets. The project also includes planned
outdoor amenities, including a new plaza and promenade, and a variety of open spaces, to enrich the neighborhood.
SoLi is a large multi-phase development project that is currently constructing the Phase 1 building (1099 Osage) and site plan in
the Northwest corner of the development. Active and continuous community involvement and support has contributed to the
development of the Master Plan that was created in September 2009 and the Neighborhood Plan that was approved in
September 2010. An ongoing group of committed stakeholders have focused on defining the project goals and vision, and have
begun to identify the design elements of the project. As the SoLi project has been selected to receive support by the Partnership
agencies (HUD, DOT, and EPA), DMA plans to utilize this interagency support to execute the vision and ideals for the project.
Although future phases of the project included in the SoLi Master Plan are awaiting funding and have not yet been designed, the
scope of the Stormwater/Green Infrastructure Charrette focused on the full development of all future phases of the SoLi
development and surrounding neighborhood areas. The charrette utilized the efforts and progress to date, and allowed
opportunity to further define the project's vision and next steps.
2.1 Framing the Problem
The SoLi project sits at the top of the Curtis Street Outfall Watershed that drains North and East into Cherry Creek and eventually
the South Platte River. This project has the potential to significantly improve the quality and quantity of the stormwater flowing out
of the watershed but it is unclear which strategies will be most effective at SoLi and how these strategies will compliment other
efforts in the watershed. Although there are questions about the technical and financial feasibility of some innovative stormwater
strategies, the real challenge at SoLi and in the neighborhood is a lack of adequate coordination between the major developers
and landowners as well as coordination between those developers, the City, and other regulatory agencies. As one working group
put it:
" There seems to be efforts underway within silos - but not between..." - a comment from the charrette
The SoLi project team and other developers in the Curtis Street Outfall Watershed need to find a way to break down the barriers
between the key players in the neighborhood and develop a comprehensive stormwater plan that is feasible, and benefits the
neighborhood and all of the parties involved.
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2.2 Charrette Process
DMA is committed to making the South Lincoln Redevelopment Project a successful development that includes progressive
stormwater management strategies addressing both water quality and quantity for storm and surface water. The purpose of the
charrette was to identify the current efforts, barriers, opportunities, and key partners for creating a comprehensive stormwater /
green infrastructure solution for the DMA project and the Curtis Street Outfall Watershed.
The "Leadership Team" below was responsible for planning the charrette. This effort included defining the overall charrette goals,
identifying the scope of any analysis needed, and ensuring that charrette outcomes and lessons learned are distributed
throughout the Partnership agencies to support implementation on the SoLi project. This team included representatives from each
of the Partnership agencies as well as the design and technical assistance team. The members of this team included the
following:
Devon Bertram, YRG sustainability
Cindy Cody, EPA Region 8
Kimball Crangle, DMA
Greg Dorolek, Wenk Associates
Stacey Eriksen, EPA Region 8
Rebecca Fox, SRA International
Jim Godwin, Vision Land
Narada Golden, YRG sustainability
Jay Peters, Vision Land
Josh Radoff, YRG sustainability
Bill Wenk, Wenk Associates
The Stormwater / Green Infrastructure Charrette was an 8-hour session that occurred on December 6th and 7th of 2010. A
charrette is an interactive meeting with a large group of stakeholders that is intended to generate innovative design ideas, identify
strategies and barriers to implementation, and build key partnerships. The Stormwater / Green Infrastructure Charrette
participants were introduced to the analysis completed by Vision Land Consultants, Inc., and were then asked to focus on
PARTNERSHIPS and TECHNICAL solutions in the working groups and discussions by first identifying current stormwater efforts,
barriers, and key stakeholders in the neighborhood (Day 1), and then exploring solutions to some of the major challenges (Day 2).
The following report is a summary of these discussions and working groups' outcomes.
2.3 Stormwater / Green Infrastructure Charrette Goal
The Stormwater / Green Infrastructure Charrette goal was developed to guide the charrette agenda, discussions, and working
groups. Charrette participants discussed and agreed to this goal at the beginning of the charrette.
Identify the current efforts, barriers, and opportunities to creating a comprehensive stormwater/ green infrastructure
solution within the DHA site and develop an implementation plan to increase interagency collaboration on these issues
in the regional watershed.
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3. Stormwater Management Strategy Overview
Charrette participants divided into working groups to discuss stormwater management strategies, current efforts, major barriers,
and key partnerships for a regional approach. They were also asked to develop separate implementation plans focused on
funding opportunities, policy and coordination, technical solutions, and operations and maintenance. Below is a summary of the
outcomes from these working groups divided into three broad categories.
g SITE BASED STRATEGIES
P
Site-based strategies include all stormwater iniatives included in the building
designs and on the Soil Development property
L
RIGHT-OF-WAY STRATEGIES
Right-of-way strategies include all stormwater efforts in the public right-of-way
.
-i-*-
Shared regional strategies include comprehensive stormwater initiatives within the Curtis Street Outfall Watershed and require collaboration and coordination between
key stakeholders.
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3.1 Site Strategies
Although stormwater management extends beyond the Soli property and needs to be addressed at a regional level, DMA has the
ability to significantly improve the current stormwater issues by implementing LID strategies within the Soli Redevelopment
Project. This impact will extend beyond the property boundaries by reducing the frequency of surface discharges into the RTD
light rail station, the frequency of split flows to the west at 13th Ave. and reduce the Total Suspended Solids (TSS) leaving the site.
Soli will have approximately 82% imperviousness made up of 23 new buildings (including townhomes and mid-rise buildings 3-8
stories in height), parking lots, alleys, improved roadways, plaza areas and green space and park areas. The Summary of Land
Uses Table and the corresponding map are based on the current Master Plan and depict the land use breakdown at the site. As
the planned redevelopment will increase the density of the site as well as improve roadways, water, sewer and stormwater
management facilities and infrastructure, various stormwater and green infrastructure management strategies have been
evaluated to determine their beneficial impact to the site.
Impact on water quantity and rate, water quality improvements, maintenance demands, and water collection and reuse capabilities
were considered for all strategies outlined below. The cost of each strategy relative to traditional stormwater management
practices has also been considered.
In addition to the site strategy analysis provided, the 1099 Osage project is a valuable Pilot project to Soli as it has implemented
many of the stormwater management and LID strategies explored for the larger development, and can provide first hand feedback
on the strategies' implementation and success.
Summary of Land Uses
Type
Perviojs
Streets
Sidewalks, Plaza Areas
Alleys and Parking Lots
Townhomes
Large Buildings
Areas not Inwoved
Total
Area (acres)
3.98
4.43
3.90
2.63
1.94
3.55
1.45
21.88
Percent of Total
18
20
18
12
9
16
7
100
LID Functions
LID Type
Porous Landscape Detention
Grass Buffer and Swales
Porous Pavement
Rooftop Detention
Green Roofs
Function
Water Quality
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Porous Landscape Detention (PLD)
Implementing deeper (6 -12") detention areas on the project site and adjacent to
buildings can improve water quality and provide modest improvements to water
quantity. This strategy has a moderate cost impact in comparison to the other
site strategies explored. Maintenance demands including trash removal and
safety / trip hazards would need to be considered.
Grass Buffers and Swales
Providing additional vegetated areas such as grass buffers and swales within the
development can also help manage and improve water quality on-site, and is
considered a low cost strategy (capital cost only) relative to traditional
management practices. These strategies can be implemented along parking lots
and within streetscapes.
Porous Pavement
Porous pavement can be implemented in the alleys and parking lots within Soli,
as well as the plaza areas to improve water quality and support detention of the
100-year flood. These areas make up 30% of the Soli development. The 1099
Osage pilot project is implementing porous paving on-site, so can provide
valuable information in regards to installation, maintenance, and costs of the
strategy (estimated as moderate in comparison to traditional approaches).
Rooftop Detention
Providing rooftop detention on buildings with flat roofs at Soli can greatly support
the management of the 100-year flood, and is considered a very low cost
strategy requiring little maintenance. By incorporating weirs at the roof drain
inlets, the roof is able to create temporary ponding and slow the release of
stormwater. Additional research is needed to determine if and how rooftop
detention can help to improve water quality. This strategy could also support
water reuse for on-site demands if it can be approved as a pilot project through
the City.
Green Roofs
Green roofs, although a higher cost strategy, can provide numerous benefits to
the Soli development. While improving water quality and supporting some
stormwater detention, green roofs can also improve building energy use, provide
green amenity space, provide habitat for increased biodiversity, and support
reducing the urban heat island effect.
BMP Performance Analysis
Urban Storm Drainage: Stormwater Manual - Volume 3
UDFCD BMP
Grass Swale
Grass Buffer
Constructed
Wetland Channel
Green Roof
Permeable
Pavement Systems
Bioretention
Extended
Detention Basin
Sand Filter
Constructed
Wetland Pond
Retention Pond
Underground
BMPs
UDFCD BMP
Grass Swale
Grass Buffer
Constructed
Wetland Channel
Green Roof
Permeable
Pavement Systems
Bioretention
Extended
Detention Basin
Sand Filter
Constructed
Wetland Pond
Retention Pond
Underground
BMPs
Hydrologic Processes
Peak
Flow
Attenuation
I
I
I
P
P
P
P
P
P
P
Variable
Volume
nfiltration
S
S
N/A
S
P
P
I
P
I
I
N/A
Evapo-
transpiiation
I
I
P
P
N/A
S
I
I
P
P
N/A
Treatment Processes
Physical
Sedimentation
S
s
P
N/A
S
P
P
P
P
P
Variable
Filtration
S
s
s
P
P
P
N/A
P
S
N/A
Variable
Straining
P
P
P
N/A
N/A
S
S
N/A
&
N/A
Variable
Chemical
Adsorption/
Absorption
S
S
s
I
N/A
S1
S
s1
P
P
Variable
Biological
Biological
Uptake
S
S
P
P
N/A
P
I
N/A
P
S
N/A
Notes:
P = Primary; S = Secondary. I = Incidental; N/A = Not Applicable
Depending on media
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3.2 Right-of-Way Strategies
One of the ideas that was discussed extensively at the Stormwater / Green Infrastructure Charrette was constructing stormwater
BMPs into the public right-of-way. This idea would allow more land area within a given acre to manage stormwater because the
streets, sidewalks, and planting strips next to the sidewalks are not typically used to manage stormwater. It could also allow some
developers to build out more of their property because they would need less land dedicated to stormwater management. Finally,
stormwater management strategies in the public right-of-way would create a unique identity in the neighborhood by acting as a
visible commitment to regional stormwater management and sustainability.
Representatives from the City of Denver Public Works department who attended the charrette were open to this idea as they are
willing to investigate green infrastructure solutions, yet wanted to ensure that any development within the right-of-way did not
significantly increase the City's liability or operations and maintenance costs. Several questions and concerns about right-of-way
developments included:
Safety: There is concern that open stormwater detention basins directly adjacent to sidewalks and the street (similar to
the one shown on the left) could become a safety hazard. Since these basins are typically 12-18 inches deep and are
surrounded by a continuous 4-6 inch curb, it is possible that they could become a tripping hazard. The city has approved
a basin with no curb at DHA's 1099 Osage project but this design requires a full grate to cover the depressed area.
Furthermore, the fire department has required that this grate be engineered to support a fire truck. The approved design
has addressed these safety concerns but comes at a significantly increased cost.
Operations and Maintenance: The long term operations and maintenance costs for BMP strategies such as porous
landscape detention areas and permeable paving is not yet established in Denver. There is some concern that a large
number of small BMPs, all possibly different sizes and designs, could significantly increase the time and effort it would
take to maintain and repair them. It will be important for several designs to be tested and evaluated, and for operations
and maintenance efforts to be streamlined. If the city were to approve a large-scale implementation of stormwater
management strategies in the right-of-way, it may make sense to develop a training program for the contractors who
would operate and maintain these BMPs. Other cities such as Portland, OR have developed similar programs that could
act as a model for the City of Denver.
Long Term Performance: The City needs to ensure that permitted stormwater management strategies can provide
adequate long term water quality and quantity performance. If BMPs do not provide consistent performance, the City will
need to implement additional strategies to improve overall stormwater management because they are responsible for
maintaining regional stormwater quality and quantity. Because of this, it is risky for the City to test and approve new
unproven strategies. Research from local pilot projects that have installed and maintained new and innovative BMPs will
be critical for the approval of a large-scale rollout of such strategies.
In addition to the concerns outlined above, any stormwater BMP that is developed in the right-of-way will need to comply with the
right-of-way requirements of the City. This includes a possibility that the BMP could be partially or entirely dug up if the City or
another agency needs to access utilities next to or under the BMP. This ongoing cost will be seen as a major barrier for
developers, including DMA.
The following BMP strategies were identified by charrette participants and likely candidates for use in the public right-of-way.
There are a number of possible designs to each of these strategies that could make them viable and effective for the project.
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Porous Landscape Detention (PLD)
Implementing deeper (12" - 18") detention areas in the right-of-way can improve both water quality and water quantity
downstream from the development. This strategy has a moderate cost impact in comparison to the other site strategies explored
and is effective for managing sedimentation and peak water flows. As described above, this strategy would need additional
support and approval from the City in order to manage maintenance and safety demands, as well as further evaluation regarding
suitable vegetation to grow in this area.
Other cities around the country are using this strategy to manage stormwater in the public right-of-way. The City of Portland
Green Street program (http://www.portlandonline.com/bes/index.cfm?c=44407) is one example of a program that has been
developed over the last 10 years to support similar stormwater strategies.
-S"K#v-*./
-e> j_
H/orfe'ng group stefc/i of right-of-way detention basin for Denver
Porous Pavement
Porous pavement can be implemented in the roadways at Soli to manage stormwater runoff and improve water quality. Roads
make up 20% of the land area in the Soli development so this strategy could have a significant impact on the overall
management plan in addition to the strategies outlined in the Vision Land analysis included below.
The 1099 Osage project is piloting porous paving on-site and can provide valuable information in regards to installation,
maintenance, and costs (estimated as moderate in comparison to traditional approaches) of the strategy. The project could help
The City of Denver develop a long-term maintenance policy that could be used for porous paving applications throughout the city.
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3.3 Shared Regional Strategies
Most of the discussion about shared regional stormwater solutions focused more on collaboration and coordination with key
stakeholders than it did on actual stormwater strategies. The key recommendations for those discussions included the following:
Acquire funds to complete a regional stormwater engineering study and start inter-agency convening body
Complete a regional stormwater engineering study
Create a convening body that supports inter-agency communication and collaboration
Develop a funding mechanism for shared regional stormwater projects
There were also several discussions about specific regional strategies that may be important to explore further. A few of these
strategies include:
- Using a portion of Lincoln Park to detain and infiltrate most or all of the stormwater volume from the upper third
of the Curtis Street Outfall Watershed: Lincoln Park sits in almost the exact center of the Curtis Street Outfall
Watershed. This park is a major amenity for the neighborhood and is heavily used on nice days. The central location of
the park, along with its large land area, makes it an ideal place to capture and detain stormwater from large storm
events (5-year storm or larger). This solution, in conjunction with a storm sewer improvement along a portion of Osage,
would be able to eliminate all of the stormwater overflows into the RTD 10th & Osage station and slow a large
percentage of the stormwater flowing from the upper third of the watershed. A representative from Denver Parks and
Recreation attended the charrette and stated that the park may not be a viable location for managing stormwater due to
its historic nature. However, understanding that this solution could be designed so the park would flood once every 5
years or less may make this a good option to explore further.
Auraria Campus's new recreational ball fields: The Auraria Campus may be developing a new athletic complex
South of Colfax and West of Osage. Since this project has not yet been confirmed, it could be designed to manage
significant stormwater volumes from the upper half of the Curtis Street Outflow Watershed. In order for this project to
move forward as a shared stormwater strategy, the planning and coordination goals above would need to be
implemented so that other developers like DMA could provide both political and financial support for the project.
Neighborhood-wide approval of LID strategies: The LID strategies that are addressed in this report and that are
being implemented at the 1099 Osage project have the potential to manage much of the stormwater quality needs in the
Curtis Street Outflow Watershed if they are approved and installed throughout the neighborhood. This type of regional
approach will allow LID to be a major component in the regional stormwater plan.
Additional regional stormwater goals include:
Detain about 2 acre-feet immediately upstream of Colfax Avenue at Osage Street to achieve a 100-year level of service
to Colfax Avenue and eliminate the split flow to the west.
Detain about 1-acre-foot on the Auraria Campus to alleviate the split flows to the west and provide a 100-year level of
service to the storm sewer system.
Detain 3.3 acre-feet on the South Lincoln site in a regional approach rather than on an individual site-specific approach
to eliminate the overflows into the RTD light rail station and the split flow west down 13th Street for events up to and
including the 100-year event.
Mariposa and Osage Streets from 9th Avenue to Colfax Avenue have wider tree lawns that could more easily allow for
the implementation of PLDs within the right-of-way to further address water quality and flooding issues within the
watershed.
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4. Vision Land Analysis and Results
This section presents the stormwater analysis for the South Lincoln Redevelopment Site and the
Curtis Street Outfall Watershed. Discussed are the South Lincoln and Curtis Street watersheds,
the hydrology and hydraulics, results of the analysis, potential LID strategies at South Lincoln,
the benefits of stormwater improvements at South Lincoln, and regional improvements that
address the identified problem areas.
Vision Land Consultants, Inc. (VLC) conducted a hydrologic and hydraulic analysis as well as a
pollutant loading analysis for both the South Lincoln Redevelopment site and the Curtis Street
Outfall Watershed. The background and results of the analysis are discussed below.
4.1 Summary of Analysis
South Lincoln lies within a local sub-watershed that is 28 acres in size at the project outfall at 11th and Osage. There are off-site
flows from the east that enter the site from a 5 acre area, as well as a 2 acre area from the south. The watershed is 100%
developed, consisting of single-family houses to the east, some commercial development to the south, and the DMA multi-family
units.
The stormwater infrastructure serving the South Lincoln Site is limited to 12- to 21-inch diameter vitrified clay pipe storm sewers.
There are currently no water quality treatment or detention basins that serve the site. The site has mild slopes to the west at an
average of 1.5%. There is a low point at the intersection of 10th Ave. and Osage Street, preventing overland flow to the north
when the storm sewer capacities are exceeded. Runoff in excess of the storm sewer capacities flows to the west into the RTD
light Rail Station. In March of 2006, 8 soil borings were taken at South Lincoln to for structural engineering purposes, and it was
found that the soils were predominately clayey sands falling within hydrologic soil groups B and C. The clay content of the soil
varies from 5 to 45%, with an average of 35%.
LID Functions
LID Type
Porous Landscape Detention
Grass Buffers and Swales
Porous Pavement
Rooftop Detention
Green Roofs
Function
Water Quality
/
s
/
/
100-Year Detention
/
/
^
Cost
Comparison*
Moderate
Low
Moderate
Very Low
High
*For capital costs only, and does not include land values
The site is located within the upper reach of the Curtis Street Watershed which outfalls to
Cherry Creek. The watershed is served by a storm sewer system ranging in size of 12-inches to
39-inches at the outfall to Cherry Creek.
As part of this project, VLC evaluated the implementation of low-impact development
stormwater management strategies on the South Lincoln Site. LID that could be implemented
on the site are:
Porous Landscape Detention or grass buffers and swales within the green space
areas and tree lawns in the roadway right-of-way;
Rooftop detention on the multi-story buildings;
Green Roofs on the multi-story buildings;
Porous pavement in alleys and parking lots; and
Volume and Depths for LID Scenarios
Description
Detention in Pervious Areas
Only
Rooftop Detention
Rooftop Detention,
Pervious Pavement in
Parking Lots and Alleys
Rooftop Detention,
Pervious Pavement, 50%
Plaza areas with P1CP
Rooftop Detention,
Pervious Pavement, 50%
PICP, Green Roofs
Volume in Pervious Areas
(AF)
3.3
2.7
2
1.7
1.5
Depth in Pervious Areas
(ft)
0.8
0.7
0.5
0.4
0.4
PICP = Permeable Interlocking Concrete Pavers
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[tt^Bffi'i
I <ğI_L
4.2 Analysis Conclusions and Recommendations
The results of the analysis indicate the following:
The 21-inch storm sewer in Osage Street from 10th to 11th Avenue, and the storm sewer in 10th Avenue between Mariposa
and Osage have less than a 5-year capacity (this system overflows during the 5-year storm);
The remaining storm sewers in the watershed have a 5-year capacity;
Surface flows on the streets in the watershed are less than one foot deep during the 100-year storm event, except at Colfax
and Osage;
There is excessive ponding, cross-street flow, and split flow at the intersection of Colfax Avenue (arterial roadway) and Osage
Street; and
Surface flows leave the watershed at numerous locations.
During the 100-year storm, stormwater surface flows leave the watershed and discharge to the south towards the RTD light rail line
and Auraria Parkway. This occurs at the intersections of 10th and Osage, 13th and Osage, Colfax and Osage, and on the Auraria
Campus at 9th and 10th Streets. At 10th and Osage, it is estimated surface flows will enter the RTD station in a 5-year storm event.
We have estimated that the existing Curtis Street Outfall Watershed contributes approximately 20 tons of pollutants, in the form of
total suspended solids (TSS), to Cherry Creek every year. The existing South Lincoln site contributes almost 6 tons of TSS per
year. This means that runoff from the Soli site contributes almost one third of all TSS pollutants coming from the watershed and
effective stormwater strategies at Soli could provide significant improvements to water quality in Cherry Creek.
This analysis clearly shows that the La Alma / Lincoln Park stormwater system is not able to manage the 100-year storm, and in
some areas the 5-year storm. When the watershed overflows, pollutants drain into Cherry Creek and eventually the South Platte
River impacting water quality. Stormwater overflows in this watershed also impact transportation at the 10th and Osage light rail
station, on Colfax, and on all roads where overflows occur. It will be important for the City and neighborhood stakeholders to
address these issues by improving stormwater quantity and quality, increasing infrastructure, or a combination of both.
For a full copy of Vision Land Consultant's South Lincoln Redevelopment Project Stormwater Analysis go to the Appendix or the
following link.
http://vrgsustainabilitv.centraldesktop.com/denverscpcharrettesexternal/
\
O,h = 13 CFS
QIoof = 55CFS
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5. Conclusions and Recommendations
The South Lincoln Redevelopment Project has enormous potential to become a catalyst for innovative, cost effective, and
sustainable stormwater solutions that could be applied throughout the City of Denver and the regional basin. The first phase of the
project is already a pilot for several innovative low-impact design strategies and the future phases could provide the testing
grounds for the full range of LID strategies that could be applied throughout the region. It is believed that these strategies could not
only provide all of the stormwater needs required by the City at SoLi, but they could also provide benefits to other developers in the
La Alma / Lincoln Park Neighborhood and Curtis Street Outfall Watershed as part of a comprehensive regional stormwater plan.
One of the major barriers to developing a regional stormwater plan is the lack of communication, coordination, and collaboration
between major stakeholders and regulatory agencies in the neighborhood. It is also difficult for individual developers to collaborate
on a shared regional solution when they are working on various projects with different funding sources and schedules. To
overcome these barriers, key stakeholders such as the Denver Housing Authority, the Auraria Higher Education Center, Denver
Parks and Recreation, Regional Transportation District, the City of Denver Public Works, and Urban Drainage and Flood Control
will need to create a new vehicle for communicating and collaborating on stormwater projects within the region.
Two actions that are critical for achieving this goal are:
Fund and complete a regional stormwater engineering study that identifies the opportunities for cost effective and sustainable
regional stormwater solutions
Create a "convening body" that enables active communication and collaboration between these key stakeholders.
If this study and convening body are created as an outcome of the Stormwater / Green Infrastructure Charrette, it would be a major
success and significant change in the way that stormwater issues are currently addressed in the City of Denver.
Ultimately, this report is not intended as a concise summary of the presentations and discussions that happened at the Stormwater
/ Green Infrastructure Charrette. It is, in essence, a call to action; a reflection of the opinions and recommendations of the many
charrette participants and consultants involved in this project who think it is time to change the way we think about, coordinate, and
implement stormwater and green infrastructure solutions in the City of Denver.
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5.1 Funding and Incentive Opportunities
DMA will need to acquire additional funding to implement many of the strategies outline in this report. The following funding
sources were identified to help support these strategies.
Urban Drainage and Flood Control District
Environmental Protection Agency
State Revolving Funds and Clean Water Act 319 grants
Developer Stormwater Fees
Better Denver Bond Program
5.2 Strategic Partnerships
DMA will need to develop active working relationships with the following strategic partners in order to successfully implement the
stormwater/green infrastructure strategies recommended in this report.
Housing and Urban Development (HUD) - HUD can provide support for programs that support LID stormwater
strategies and implementation.
Denver Public Works (DPW) - Denver Public Works plays a critical role in the development, approval, and ongoing
management of regional stormwater management solutions in the Soli development and La Alma / Lincoln Park
neighborhood.
Denver Community Planning and Development (CPD) - Denver CPD has developed a comprehensive
neighborhood plan for La Alma / Lincoln Park and will need to be involved in many of the major decisions moving
forward.
Regional Transportation District (RTD) - RTD is affected by stormwater overflows and will need to be involved in
stormwater management strategies and solutions in the neighborhood.
Colorado Department of Transportation (CDOT) - CDOT will need to be involved if the comprehensive
neighborhood stormwater plan impacts traffic flows through the La Alma / Lincoln Park neighborhood.
La Alma /Lincoln Park Neighborhood Association (LPNA formerly known as La Alma / Lincoln Park Planning
Group (LLPPG)) - Many of the programs and infrastructure developments included in this report will not be
successful without engaging and developing support within the LALP resident community.
Auraria Higher Education Campus (AHEC) - AHEC covers roughly one third of the land area in the Curtis Street
Outfall Watershed and is currently developing new projects in the area.
Urban Drainage and Flood Control District (UD) - Urban Drainage and Flood Control District oversees
comprehensive stormwater management strategies for areas in and around the City of Denver.
Denver Parks and Recreation (DPR) - DPR owns and maintains Lincoln Park which covers a large land area in the
middle of the Curtis Street Outfall Watershed.
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6. Appendix
6.1 Charrette Agenda, Presentations, and Handouts
The agenda, a PDF of the PowerPoint presentations, and all handouts for the Stormwater / Green Infrastructure Charrette
have been posted on a public website for participants and the general public to access. Go to the following website to access
those documents.
http://vrgsustainabilitv.centraldesktop.com/denverscpcharrettesexternal/
6.2 Charrette Photos
Go to the following link to see photos taken during the Stormwater / Green Infrastructure Charrette.
http://picasaweb.google.com/yrgconsultants/PSCCharrettes?feat=directlink
6.3 Charrette Notes
The following pages contain all of the notes that were recorded on flip charts and taken during the discussions and working
groups in the Stormwater / Green Infrastructure.
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Charrette Notes:
EPA Stormwater Charrette Notes (Transcribed):
South Lincoln Redevelopment
Stormwater/Green Infrastructure Charrette: December 6 & 7
Charrette Notes: Flip Chart Notes / Discussion Notes
Stormwater/Green Infrastructure Charrette Goal:
To identify current efforts, barriers, and opportunities to creating a comprehensive
stormwater/green infrastructure solution within the DMA site and develop an implementation
plan to increase interagency collaboration on these issues in the regional watershed.
Day1:
What metric is used if discussing 'success' for stormwater management?:
Effective imperviousness; how much of the total project area can absorb run off
Meets regulatory requirements and adds value (measurable financial value) to site
(e.coli issues, sedimentation issues, etc.)
Watershed/WQ issues - amount of water leaving site, rate / quantity; quality
Don't adversely affect those down stream
Lasts a long time, robust and durable
Reduction of utilities, how will this impact reducing utility and ongoing
maintenance?
Profitability / marketability to other investments in neighborhood
Finding solution that fit the site - not a one size fits all solution
Considerations:
How do we approach with 'this is overarching umbrella strategy?'
How do we incorporate strategies in a phased manner on site? How do phases 2,
3, 4,etc move forward in overarching plan?
How can 1099 present a successful test case?
Current Public Works process:
Concerned with maintenance, safety, aesthetics and functionality
Maintenance of retention at DHA Site is ok because it is tied in well - developing a
green job core
Maintenance requirements / Issues:
Remove sedimentation in each of the basins on a regular basis
Regular fixing and upkeep
Utilities are required under some of these strategies (e.g. porous paving) and need
to be taken care of (e.g. Denver water may lie new line with porous paving, and
then later put asphalt over porous paving)
It is expensive to make grates flush (however east coast has been able to
implement better strategies and design that allows them to not be as expensive)
Regular trash removal
Day 1: Guiding Questions for Brainstorming Groups (5 Groups):
1. How does stormwater landing on the site and streets within the DHA development
at 10th and Osage impact the following agencies? (DHA, RTD, Public Works, EPA,
Urban Drainage, Auraria Campus, Denver Water)
2. What current efforts are in place within these agencies to address stormwater in
this neighborhood?
3. Do you have long-range plans that include attention to this area?
4. How do these agencies currently work together around stormwater issues?
5. What funding is in place to support stormwater improvements in this
neighborhood? If this funding is allocated for specific improvements, what are
they?
6. What are the regulatory and procedural obstacles to implementing a
comprehensive stormwater strategy on this site?
7. What other barriers will limit or prevent a comprehensive stormwater solution
within this development?
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Day 1: Group 1
Day 1: Group 2
1. Impacts
EPA - environmental standards; water quality
City- Liability, transportation, aging infrastructure, storm capacity
DMA - Access and safety; liability; funding; ongoing maintenance
Auraria - Capacity; funding; maintenance; short-term fix
2. Current Efforts
EPA - Collaboration with Fed. Family and local organizations; exploring the "what
if
City - Streamlining permit process; Better Denver Bond projects; Long-term goals
DMA - Healthy development measurement; 6 "liability principles"
Auraria - project evaluation of current system; fostering spirit of collaboration
3. Plans
Yes.
4. Current Cooperation
City - regional detention solution with private partner opt-in/pay-in
Auraria - Maintenance and students doing projects; urban drainage funds
5. Funding
EPA - creative connecting for grants
DMA - allocation for "greening"
Auraria - dealing with land limits; project by project
6/7. Obstacles/Barriers
- Federal/State/Local ordinances
- Water rights issue
- Theory vs. practice (competing interests; liability)
- Maintenance responsibility
- Cost effectiveness
- Short term funds for long term goals
1. Impacts
DMA- address site drainage; BMP maintenance
RTD - flooding operations
EPA - support sustainable community(ies) initiative; funding opportunities
Auraria - limited impacts
Urban Drainage - potential increased impact to downstream facilities
Denver Water - irrigation/water harvesting; future potential
City - manage infrastructure; BMPs; site plan review; inspect and enforce
2. Current Efforts
DMA - Phase 1 1099 Osage project and Master Plan initiatives
RTD - Discussing potential partnership w/ DMA to address station area flooding
Denver Public Works - Phase 1 1099 Osage project and future plan review;
development services
EPA - project involvement and monitoring
Denver Water and AHEC - public involvement
3. Long-range Plans
City - Master Plan
DMA - Master Plan for site
EPA/Urban Drainage - use as potential neighborhood redevelopment model
AHEC - future nearby athletic fields
4. Current Cooperation?
(see drawing on flip chart Day 1: Group 2 p. 2)
5. Funding
Urban Drainage
6. Regulatory and Procedural Obstacles
Water Rights?
Soils (in certain areas)
ADA accessibility/connectivity
Development standards/procedures
Safety and health (i.e. fire truck accessibility, etc.)
Cost and maintenance
MS4 requirements (City and RTD)
7. Other Barriers
Agency culture
Funding
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Day 1: Group 3
Day 1: Group 4
1. Impacts
DMA - developers who must comply with regulations
RTD - overflows stop train traffic
Public Works - improvements can shift and lower capital costs of storm sewer
upgrades
EPA - Water quality/human health impacts of flooding
Urban Drainage - Maintenance and improvement
Auraria - Save money on vaults
Denver Water - Conservation measures can impact water rights/usage; Future
rate impacts
2. Current Efforts
"There seems to be efforts underway within silos but not between."
RTD - study initiated to solve flooding problem
City/Wastewater - Capital Improvement Plan (CIP)
Auraria - Individual schools building solutions to flooding
DMA - Implementing site solutions for 1099 Osage project
"Timing of projects among these groups is a problem"
Metropolitan State College of Denver is building vaults now
RTD feels a sense of urgency
DHA's timeframe is longer
"Less expensive 'temporary' solutions might accommodate these timing problems."
"The 'efficiency' of vaults to private developers who buy/own expensive urban land. What are
other potential options? - Chicago's 'Green Alleys'."
3. Long-Range Plans (See #2)
4. Current Cooperation?
Generally, agencies are not working together.
But they are all here today (at the charrette).
5. Funding
"Even if you can show that a regional solution is cheaper than one silo's solution:"
- Who handles the money?
- Who oversees the projects?
- Who monitors the projects?
6. Obstacles/Barriers
"We lack a leader for unifying the stakeholder agencies."
1. Impacts
EPA-Ecoli, TMDL
City- Flooding @ RTD, Storm Capacity, Maintenance
DMA - Access and Safety, Liability, Maintenance
Auraria - Capacity, maintenance
RTD - Flooding
2. Current Efforts
RTD - Flooding study in place
City - CIP: City's plan vs Public Works plan
Auraria - has buildings in design and construction phases with detention basins
DMA- 1099 and Master Plan -> formalized
"There is a great need for plans to work together"
3. Plans
First development gets to use stormwater capacity.
City has stormwater plan but this area is not a priority project.
Formalization of stormwater strategies from 1099 into Master Plan, outcome from
this charrette.
4. Current Cooperation
Happens at the site level -> There is a need for looking at the bigger picture.
There is a need for an on going forum -> needs specific project, specific goal
5. Funding
Need upfront capital for a comprehensive/regional solution
- May have interim solution?
- Participation of other agencies
6. Obstacles/Barriers
Water law
Funding
Integration of agency agendas
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Day 1: Group 5
1. Impacts
DMA - 10th and Osage station flood; no flooding for structures (density; project
cost; design); undersized systems
Public Works - Capital improvement needs; partnerships needed for maintenance;
money is needed for this basin
PW/Urban Drainage/developers - New BMPs from update; the nontraditional may
be tested
EPA - water quality, stormwater regulations
"Which agency is responsible for looking at the big picture?"
2. Current Efforts
DMA - Start w/ Phase 1 1099 Osage project; design Master Plan
PW - no efforts, nothing in the 6 year plan
EPA - pay for charrettes, water quality improvements for S. Platte/Cherry Creek
3. Long-Range Plans
DMA - will have to do flood control in a more constrained way because the agency
is undersized
PW - don't put too much effort on the 6 yr plan.
"A financial partnership will have to be made to do it right - fix upstream sites."
4. Current Cooperation
Site solutions vs Regional Improvements (no funding): Agencies must work
together on site solutions
Agencies can identify regional solutions through design criteria
Interim measures/options impact the fee structure (upfront $$)
5. Funding
No regional project money
Development paid site by site
Future Bonds?
Next Building HOPE VI
6. Obstacles/Barriers
Water Law
Grand Partnering
Money
Timing
Multi-jurisdictional problems
Day 1: Breakout Notes and Further Questions:
-What mechanisms exist for outside organizations to work with the city around stormwater
issues and coordinated funding?
- Are there bonding structures to fund a comprehensive 30-40 year solution?
- Where do you find the land?
- How do you set up a fee structure to pay for a Comprehensive Plan?
- Is there tension between having BMPs and Active Zones? (Currently, BMPs do not count
as open space)
-The solution for water quality will likely focus on a 2-year storm. This is different than
focusing on flooding and there is a clear need for focus and balance here
- We are also in need of a forum where we can discuss these issues
- We need to develop incentives to encourage developers and agencies to participate in this
forum (highlight the risks of not participating)
- Timing is a huge funding issue
- How do we encourage participation in a regional solution? How do you illustrate financial
benefits of participation?
Current Cooperation:
- "Flooding can be service issue for RTD"
- RTD right-of-way (ROW) could be shared
- RTD can contribute money or land
- Auraria downgradient - looking at building vaults
- LaFarge as a possible partner
- Maintenance issues for Denver Water for pervious pavements
- State role - funding pieces of watershed planning education and outreach, projects
- Opportunity to redefine urban priorities
Habitat for Humanity has tried to implement SW BMPs (eg porous concrete)
Obstacles:
Denver Parks - historic park
Approval of innovative BMPs by City
SW fee structure
Preference for traditional SW measures
Disconnect between funding sources and cycles
Unknown cost of maintenance for new BMPs how to bring together everyone
for planning
Planning scales are different as well as timeframes and levels of urgency
How to pay for long term incremental improvements that are part of a long
term goal
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Day 2:
Day 1 RECAP (big issues and ideas):
There are different schedules / timeframe for everyone involved. Particular set of
issues (DMA, Auraria, the city) puts SW process / implementation on different
timeframe, but all are invested in working with the city
o Individual players have common problems but are all on individual
schedules. Need coordination of funding and planning, however these
are difficult to align
Investment: city doesn't look at investment in terms of capital improvements, works
in very limited perspective; a political issue.
o In order to get to sustainable solution, need to get the money in at the
right cycles, bonding, etc.
Don't want to mix water quality with early needs for flood control:
o Distinction between water quality short term needs vs flooding needs
o Bigger pipe does not benefit people downstream - water quality is
integral to flooding issues
Current DMA Master Plan has budgeted to facilitate all rules and guidelines for
DHA's site, but does not consider regional approach
Vision Land Analysis Discussion
Can rooftop detention include a water quality component? (sand filters, etc.?).
o maintenance may be an issue, and it's not a design standard so would
have to overcome these hurdles for implementation
Grass buffer and swale costs only includes capital costs, does not include land
value so cost could potentially be much higher
Detention volumes include 22-23 acre site, not only development site of 17 acres
Have there been revisions to policies within cities to incorporate maintenance and
regulation requirements. What would this take to do in Denver?
o pilot program...
A challenge in this area will be the soil conditions - soils vary in type and depth
dramatically across the site (clay ranges from 5-45%).
Master Plan needs support from city for ROW improvements
Proposed strategies are only meeting the city's SW requirements, not going above
and beyond (not all meet LEED or Enterprise criteria)
Cost of last step "is not feasible for individual developer" - way too much money
If any of these steps are implemented, it will benefit neighboring lands as well
o Because of this, how would neighboring lands' plans change and be
modified?
o How is this done with the varying project timeframes?
Vision Land Analysis Discussion (Cont.)
Don't want to implement strategies of lost opportunity costs - have ponds instead
of functional landscape features
Next level of analysis would look at how grading works, how to phase strategies,
etc.
RTD would be more interested in regional solutions
How do we ensure strategies are going to work as well as existing conditions (and
ideally better)?
After Colfax, have to deal with major overflow
At Auraria, can this all be dealt with on site?
Where are we going to get economies of scale?
Main concern is not 5 or 10 year storms, its 100 year storms: build these strategies
into infrastructure (i.e. storage in roads, etc.).
o Try to separate extreme events around / out and may come up with
better cost solution
4 Working Groups:
1. Funding/Policies
2. Coordination and Planning
3. Operations and Maintenance
4. Technical Implementation
4 Brainstorming Tasks / For Each Recommendation:
1. Identify Principles
2. Recommend Step-by-step Implementation Strategies
3. Identify Elements of Success
4. Identify Resources
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Day 2: Funding Group
-What would the funding opportunity be with a regional approach?
-20 year life cycle for operations and maintenance
-Who funds capital?
o RTD
o Auraria
o DMA
o Smaller Developers
-An incentive program
-Temporary detention approach
-Water harvesting over 8 years
-Proportional share
-EPA provides $2 Million/annually to state water quality division for non-point source projects
(competitive process once a year)
-Create stormwater utility
-Bond issue
-State revolving loan funds ($30 Million)
FUNDING GROUP REPORT OUT
Main focus: Identify the need ("ask") and figure out proposal to request this
What resources would be available to help fund this? (approach by site or basin-
wide?) = BASIN WIDE
o Need to start with joint engineering study that would explore
alternatives to help flooding issue - RTD, Auraria, DMA, smaller
developers -this would identify solutions, priorities, requirements,
funding/cost requirements, etc.
This would look at WQ and flood control
This study could be a next step to Vision Land's analysis, cost
benefit analysis, showing different solutions beyond just DMA
site. How does DMA tie into Auraria and surrounding areas?
o Research grants available from state WQ nonpoint source or state
revolving fund
There is a pool of money received from EPA (section 319,
nonpoint source) - annual grant cycle (can be tricky in urban
corridor - No precedent in the urban corridor in CO). Close to
$2 million available every year, half of which is pretty flexible to
use on state-wide demo projects/info & education projects esp
with LID strategies (typically work on a lot of mining and ag
sites; want to link with land use planning related to water
quality)
State revolving fund: Wastewater utility is common recipient,
could maybe fund engineering study
o Issuing bonds? (depends on source of issuing agency) - this would pay
for capital costs of implementing the solution (whatever this would be)
o Once study completed, look at everyone's portion required to fund the
ultimate goal and meet requirements, and determine what share of the
cost everyone would owe
City and county of Denver has requirements to meet 5 year storm event. This is
not met in this area.
Possible Resource:
o Identify a temporary or short term solution (i.e. detention area that can
be taken out when funding becomes available) - this could buy some
time for the project
o Fund the study while fund temp solution
Elements of Success
o Fixing the problem, Getting it done
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Day 2: Coordination and Planning Group
- RTD - issues at 10th and Osage and Colfax and Osage
- DMA will help 10th and Osage, but not Colfax and Osage
- Expand analysis and depth of other parts of drainage basin
- DHA's work lowers priority for RTD to do additional work
- In need of a convener with institutional knowledge, capacity, clout: ie, Urban Drainage, City
of Denver
- Potential to create a stormwater metro districts)?
-Link districts to area of change or station areas
-Ability to fund/tax
-Boundaries and participants
-Put stormwater tax into district fund instead of a general fund
-Solve issues cooperatively to lower the stormwater fee
-Resources - Funding to support stormwater district convener
-Principle - coordinate large-scale stormwater management
-Implementation - convener; prioritize plans for each basin
Elements of success - A coordinated plan
-Principle - review Capital Improvement Plan (CIP) criteria to refine project priority and
stormwater master plan priorities
-Stormwater money as seed money for coordinated effort
- City as convener for continued work on site (stormwater/wastewater)
- New partners - 13th and Osage; Colfax and Osage
- Define boundaries of project area
- Engage Auraria with their detention issues
- City convene by January
- EPA/HUD/DOT/RTD co-convene with City
- EPA support as resource
- Technical design
Meeting #1: Collaboration and funding for technical study; define boundaries and scope
COORDINATION AND PLANNING REPORT OUT
Only a few are defining the watershed. Fewer partners are better.
How do we move forward with planning?
o Have a convener because some entity needs to take the responsibility
(i.e. the City, EPA?) to help coordinate and organize these efforts, and
act as technical review point of contact
o Timeframe is very important here. Need interim agreement because
everyone is under tight timeframe
o Need to have a technical study to definitively look at alternatives (park,
Auraria ball fields, looking at water quality, etc.)
What's the nature of a district?
o Areas of change, new zoning codes, station areas = any areas that have
large investments
o Be able to be flexible and aware where there are pockets of
development; understand their issues and acknowledge overall solutions
o Difficulty is that there is no 'hammer' to get this done - there needs to be
a public entity
o Where are the boundaries?: keep it within the basin (however, auraria's
ball fields are in another basin...)
The goal of the convener is to establish a technical study; plan to have a
meeting in January to get people talking and looking at what needs to be
discussed, what agencies should participate and develop an agreement to
collaboratively work together. Once this agreement is in place, identify who has
funding, what the partnerships and resources are, and the next steps.
Partnership for Sustainable Communities EPA Brownfield Pilot - Denver, CO 25
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Day 2: Operations and Maintenance Group
-Depends on design selected
-Owner is responsible for maintenance
-Green Infrastructure O&M cost maybe higher than conventional O&M
-DMA has to do/conduct maintenance as per regulatory requirements
-Use "outside" contractors to do O&M
-Green Team
-City does maintenance at a higher, inflated cost
-DMA hires a green team director
-Study other successful "green jobs" programs
-Possible partnerships with existing green jobs providers (e.g., community colleges,
consultants)
-Green team director to evaluate scope of O&M at Lincoln Park Project
-Work with city to determine scope of work of BMPs in place
-DMA Housing management program Section 3
-Recommendation: "City Plays Nice"
OPERATIONS AND MAINTENANCE REPORT OUT
Suggestions:
o Site specific design
o Owner is responsible for maintenance
o Options to take care of strategies are to: look at existing housing
management, outside contractors or the city at a much higher cost
o Have a current tax law or assess an extra cost / sf to be for maintenance
(there is current storm drainage fee)
o Green team: hire a director to see what demands are across portfolio
and begin a program; identify who partners may be; what resources are
available? (DHA has section 3 requirement)
o Will City have to have a work force to discuss LID strategies and
implementation?
Yes, as it gets more complicated. Currently there is not a
maintenance / ops team that deals with the green strategies
o Some cities stormwater groups offer training for maintenance and
construction workers
Denver is going to need to do this - right now, will do this for
construction activities only
- Look at Portland's Green Street stewardship program as
example
26 Partnership for Sustainable Communities EPA Brownfield Pilot - Denver, CO
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Day 2: Technical Implementation Group
-Regional solutions
-Right of Way (ROW) PLD's w/100 year
-Hybrid System
-Separating Water quality and quantity and 100-yr (parking and streets)
TECHNICAL IMPLEMENTATION REPORT OUT
Regional solutions: biggest restriction on site is 10th & Osage sewer. In order to
increase conveyance here, can upsize pipe to west and manage additional
capacity; add improvements in ROW (focused on flood control). Also look at how
Colfax is influenced and impacted.
o Identified site on park to manage 25-100yr flooding AND storage
opportunity in Auraria sports complex - however, time and money are
the main issues. Alternative is sub-regional approach to manage water
on-site only
Historic park has some issues / reqs. Neighborhood is dense
so park is being used quite a bit.
Need to assure maintenance and usability (however,
this is going to only be used once every 5 years)
sensitive issue to use parks, need to be very specific
on what parks are going to be used for and what
they need
What is depth? Driven by invert of pipe more than by the depth
o Putting in LIDs in ROW: manage water quantity volumes for 100-year
storms (see Jay's Image) and water quality treatment.
Concept is approved, but not in the ROW (detention is not
approved in ROW, but precedent is other parts of the country)
What is depth? Driven by invert of pipe more than by the depth
needed
o Consider using rooftop detention for site - use water for reuse, New
Mexico is doing this and can do this. Colorado can pursue through pilot
projects.
How do we manage risks? This needs to be further evaluated and determined,
look at:
o Need to evaluate risks related to fire trucks, safety, parking
requirements, transportation / pedestrians, building in the ROW, etc.
o Look at what is happening / what is happening in these areas? Are there
risks? What has been done and what is happening? (i.e. trip hazards,
how does snow impact the proposed solution?)
Consider if EPA can do this research
Larry's example of New Hampshire porous pavement ok with
snow
Consider a hybrid system
Resources / Tools:
Urban Drainage Stormwater tool
Volume 3 water quality manual just been released (posted last week)
Sustainable sites initiative
Overall Next Steps:
Convener meeting in January
Joint engineering study
Research grant opportunities that can help fund engineering study
Set up meeting with Fire Dept
Look at precedent
o Portland's Green Street stewardship program (green team)
o East coast case studies / costs on implementing flush grates with
success and low cost
o Larry's example of New Hampshire porous pavement - proved to be ok
with snow
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6.4 Charrette Attendees:
First Name
Tamara
Eric
Terry
Devon
Andy
Cindy
Matthew
Kenneth
Brad
Devon
Amy
Cindy
Kimball
Michelle
Greg
Stacey
John
Saeed
Rebecca
Kristin
Jim
Narada
Karen
Nicole
Guadalupe
Last Name
Allen
Barendsen
Baus
Bertram
Blackmun
Bosco
Brady
Brewer
Buchanan
Buckels
Clark
Cody
Crangle
DeLaria
Dorolek
Eriksen
Ewy
Farahmandi
Fox
Fritz
Godwin
Golden
Good
Harwell
Herrera
Organization
Water Quality Control Division
Department of Energy
Denver Public Works
YRG sustainability
Habitat for Humanity Metro Denver
Greenprint Denver
-
Denver Development Services
BYG Group
City and County of Denver Parks and
Recreation
EPA Region 8
EPA Region 8
Denver Housing Authority (DHA)
CO Dept of Public Health and the Environment
Wenk & Associates
EPA Region 8
RTD
Denver Community Planning and Development
SRA International
Denver Community Planning & Development
Vision Land
YRG sustainability
Denver Public Works
RTD
HUD
First Name
Jack
Kenneth
Abigail
Peter
Jill
Elaine
Charles
Jon
Chris
Jody
Christopher
Jay
Holly
Susan
Josh
Tim
Larry
Karl
John
Eddie
Brian
Alan
Ryan
Bill
Len
Last Name
Hidinger
Hoagland
Holmquist
Hynes
Jennings
Lai
Lawton
Novick
Olson
Ostendorf
Parr
Peters
Piza
Powers
Radoff
Rehder
Roesner
Schemling
Shonsey
Sierra
Smith
Sorrel
Tobin
Wenk
Wright
Organization
EPA Region 8
Community Capital Corp
Denver Water
South Lincoln Steering Committee
Auraria Higher Education Center
EPA Region 8
EPA
Denver Dept of Env Health
CSU
EPA Region 8
Denver Housing Authority (DHA)
Vision Land
Urban Drainage and Flood Control
Urban Ventures
YRG sustainability
EPA Region 8
Colorado State University
Denver Development Services
RTD
EPA Region 8
EPA
Denver Development Services
Denver Housing Authority (DHA)
Wenk & Associates
UC Boulder
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6.5 Acronyms List:
Acronym
AHEC
BMP
CCoD
CDOT
CPD
DMA
DOT
DPR
DPW
EPA
HUD
LA/LP
LID
LPNA
OBLR
PICP
PLD
ROW
RTD
Soli
TSS
UD
VLC
Auraria Higher Education Campus
Best Management Practice
City and County of Denver
Colorado Department of Transportation
Denver Community Planning and Development
Denver Housing Authority
Department of Transportation
Denver Parks and Recreation
Denver Public Works
Environmental Protection Agency
U.S. Department of Housing and Urban Development
La Alma /Lincoln Park
Low Impact Design
La Alma Lincoln Park Neighborhood Association
EPA Office of Brownfields and Land Revitalization
Permeable Interlocking Concrete Pavers
Porous Landscape Detention
Right-of-Way
Regional Transportation District
South Lincoln Redevelopment Project
Total Suspended Solids
Urban Drainage and Flood Control District
Vision Land Consultants, Inc.
Partnership for Sustainable Communities EPA Brownfield Pilot - Denver, CO 29
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6.6 Vision Land Report
MEMORANDUM
To: Rebecca Fox, SRA International, Inc.
Narada Golden, YRG Consultants, Inc.
From: Jay Peters, PE, Vision Land Consultants, Inc.
Date: January 24, 2011
f?e; South Lincoln Redevelopment - EPA Charrette
Summary of Stormwater Analysis for Report
This technical memorandum provides the analysis write-up for the Stormwater charrette report as presented in the draft report outline dated 12/10/10 by YRG.
3.0 Vision Land Analysis
This section presents the Stormwater analysis for the South Lincoln Redevelopment Site and the Curtis Street Outfall Watershed. Discussed are the South Lincoln
and Curtis Street watersheds, the hydrology and hydraulics, results of the analysis, potential LID strategies at South Lincoln, the benefits of Stormwater
improvements at South Lincoln, and regional improvements that address the identified problem areas.
3.1 Regional Watershed Analysis
Vision Land Consultants, Inc. (VLC) conducted a hydrologic and hydraulic analysis as well as a pollutant loading analysis for both the South Lincoln
Redevelopment site and the Curtis Street Outfall Watershed. The background and results of the analysis are discussed below.
3.1.1 South Lincoln Watershed
The Denver Housing Authority is planning to redevelop the South Lincoln Public Housing Site. The site is located in the La Alma/Lincoln Park neighborhood
south of downtown Denver near the Buckhorn Exchange Restaurant. The site currently consists of 270 public housing townhome units on 15.1 acres. Also within
the site are the RTD light rail station, a commercial site, parking lots both paved and earthen, and the Buckhorn Exchange Restaurant.
South Lincoln lies within a local sub-watershed that is 28 acres in size at the project outfall at 11th and Osage. There are off-site flows from the east that enter the
site from a 5 acre area, as well a 2 acre area from the south. The watershed is 100% developed, consisting of single family houses to the east, some commercial
development to the south, and the DHA multi-family units.
The Stormwater infrastructure serving the South Lincoln Site is limited to 12- to 21-inch diameter vitrified clay pipe storm sewers. There are currently no water
quality treatment or detention basins that serve the site. The site has mild slopes to the west at an average of 1.5%. There is a low point at the intersection of 10th
and Osage, preventing overland flow to the north when the storm sewer capacities are exceeded. Runoff in excess of the storm sewer capacities flows to the west
into the RTD light Rail Station. 8 soil borings were taken at South Lincoln. Soils are predominately clayey sands falling within hydrologic soil groups B and C.
The clay content of the soil varies from 5 to 45%, with an average of 35%.
3.1.2 Curtis Street Outfall Watershed
The site is located within the upper reach of the Curtis Street Watershed which outfalls to Cherry Creek. The watershed is served by a storm sewer system ranging
in size of 12-inches to 39-iches at the outfall to Cherry Creek. The area of the watershed is 101 acres at the outfall to Cherry Creek. The watershed has a variety
of land uses, including parks, single family residential, multi-family residential, commercial, industrial, retail, and institutional. The watershed includes the RTD
30 Partnership for Sustainable Communities EPA Brownfield Pilot - Denver, CO
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light rail station at 10th and Osage, the North Lincoln Park Public Housing site, the RTD light rail line along Colfax, and the Auraria Campus at the lower reach of
the watershed. The North Lincoln Park site is served by a detention basin and 18-inch outfall pipe.
3.1.3 Hydrologic and Hydraulic Model Development
VLC used the Environmental Protection Agency Stormwater Management Model (EPA SWMM) to evaluate the hydrology and hydraulics of the Curtis Street
Outfall Watershed. The hydraulics were evaluated using the unsteady flow (dynamic wave) method to account for varying backwater conditions over time,
evaluate existing detention basins, determine pipe and street conveyance capacities, and determine divided flows within the watershed. We evaluated the
watershed for the 5- and 100-year design storm events.
3.1.4 Analysis Results
The results of the analysis indicate the following:
The 21-inch storm sewer in Osage Street from 10th to 11th Avenue, and the storm sewer in 10th Avenue between Mariposa and Osage have less than a 5-year
capacity;
The remaining storm sewers in the watershed have a 5-year capacity;
Surface flows on the streets in the watershed are less than one foot deep during the 100-year storm event, except at Colfax and Osage;
There is excessive ponding, cross-street flow, and split flow at the intersection Colfax Avenue (arterial roadway )and Osage Street; and
Surface flows leave the watershed at numerous locations.
During the 100-year storm event, stormwater surface flows leave the watershed and discharge to the south towards the RTD light rail line and Auraria Parkway.
This occurs at the intersections of 10th and Osage, 13th and Osage, Colfax and Osage, and on the Auraria Campus at 9th and 10th Streets. At 10th and Osage, it is
estimated surface flows will enter the RTD light rail station for the 5-year storm event.
We have estimated that the existing Curtis Street Outfall Watershed contributes approximately 20 tons per year of total suspended solids to Cherry Creek. The
existing South Lincoln site contributes almost 6 tons per year.
3.2 Proposed Plan for South Lincoln
The stormwater system will be improved as part of the South Lincoln Redevelopment. The improvements will be designed to meet current CCD criteria and
standards. There are opportunities to address both local and regional problems on a watershed based approach which may be more cost effective.
The project consists of new multi-story buildings, townhomes, parking lots, alleys, improved roadways, plaza areas, and green space/park areas. The site will have
about 82% imperviousness. The table below summarizes the land use areas at South Lincoln.
Summary of Land Uses
Type
Pervious
Streets
Sidewalks, Plaza Areas
Alleys and Parking Lots
Townhomes
Large Buildings
Areas not Improved
Total
Area (acres)
3.98
4.43
3.90
2.63
1.94
3.55
1.45
21.88
Percent of Total
18
20
18
12
9
16
7
100
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The planned redevelopment will increase the density of the site with mixed use including retail, commercial, multi-story residential buildings, and townhomes.
The redevelopment will occur over about a 22 acre site including improving the local infrastructure such as roadways, water, sewer, and stormwater management
facilities. The redevelopment does not include the Buckhorn Exchange Restaurant or the commercial property on the southwest Corner. The current plan for the
project includes 23 buildings, ranging from townhomes to mid-rise buildings three to eight stories in height. Roadways within, and adjacent to, the project site will
be improved to meet CCD public works standards.
3.2.1 Strategies
As part of this project, VLC evaluated the implementation of low impact development stormwater management strategies on the South Lincoln Site. LID that
could be implemented on the site are:
Porous Landscape Detention or grass buffers and swales within the green space areas and tree lawns in the roadway right-of-way;
Rooftop detention on the multi-story buildings;
Green Roofs on the multi-story buildings;
Porous pavement in the alleys and parking lots; and
Porous pavement in the plaza areas.
These strategies can have multi-use objectives, including active use areas within green space areas, and manage stormwater for both quality and quantity. The
function of each type of LID strategy is summarized in the table below.
LID Functions
LID Type
Porous Landscape Detention
Grass Buffers and Swales
Porous Pavement
Rooftop Detention
Green Roofs
Function
Water Quality
S
V
/
/
100- Year Detention
S
S
S
Cost Comparison*
Moderate
Low
Moderate
Very Low
High
*For capital costs only, and does not include land values
3.2.2 Local and regional Improvements
VLC estimated the needed detention volumes to meet CCD stormwater management criteria. The detention volumes for the site are:
WQCV: 0.8 AF
100-Year: 2.5 AF
Total: 3.3 AF
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We analyzed different scenarios using LID concepts for managing storm water, and the resulting detention volumes necessary within the pervious areas of the
development project, which are summarized in the table below.
Volume and De
Description
Detention in Pervious Areas Only
Rooftop Detention
Rooftop Detention, Pervious Pavement in Parking Lots and Alleys
Rooftop Detention, Pervious Pavement, 50% Plaza areas with PICP
Rooftop Detention, Pervious Pavement, 50% PICP, Green Roofs
pths for LID Scenarios
Volume in Pervious Areas (AF)
3.3
2.7
2
1.7
1.5
Depth in Pervious Areas (ft)
0.8
0.7
0.5
0.4
0.4
Providing water quality treatment and 100-year detention on the South Lincoln Redevelopment site will result in significant improvements to the performance of
the off-site storm system. Improvements include significantly reducing the frequency of surface discharges into the RTD light rail station, and the frequency of
split flows to the west at 13th Avenue. Total suspended solids leaving the site could be reduced by 4 tons per year.
VLC also developed conceptual cost estimates for managing stormwater on the South Lincoln site to compare traditional stormwater management facilities to LID
strategies. The costs are comparable, and are listed below.
Traditional Management: $2.46M
LID Strategies: $2.65M
The traditional management costs assumes detention in underground vaults. Both estimates are for capital costs only, and do not include land costs.
VLC evaluated other potential regional improvements that would alleviate problems within watershed. The improvements included:
About 2 acre-feet of detention immediately upstream of Colfax Avenue at Osage Street would provide a 100-year level of service to Colfax Avenue and
eliminate the split flow to the west.
About 1 acre-foot of detention on the Auraria Campus would alleviate the split flows to the west and provide a 100-year level of service to the storm sewer
system.
Implementing 3.3 acre-feet of detention on the South Lincoln site in a regional approach rather than on an individual site specific approach, will eliminate the
overflows into the RTD light rail station and the split flow west down 13th street for events up to and including the 100-year event.
Mariposa and Osage Streets from 9th Avenue to Colfax Avenue have wider tree lawns that could more easily allow for the implementation of PLDs within the
right-of-way to further address water quality and flooding issues within the watershed.
P:\2549.EO-EPA Stormwater Charrette\Documents\Reports Studies & Due Diligence\SoLi Memo.doc
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