HomeMy WebLinkAbout031 - 04/06/2010 - ADOPTING LANDSCAPE DESIGN STANDARDS AND GUIDELINES FOR STORM WATER AND DETENTION FACILITIES AS AN AD ORDINANCE NO. 031, 2010
OF THE COUNCIL OF THE CITY OF FORT COLLINS
ADOPTING LANDSCAPE DESIGN STANDARDS AND GUIDELINES
FOR STORMWATER AND DETENTION FACILITIES
AS AN ADDENDUM TO THE CITY'S STORM DRAINAGE DESIGN
CRITERIA AND CONSTRUCTION STANDARDS
WHEREAS, in 1984, the City Council adopted Resolution 1984-41, approving "Storm
Drainage Design Criteria and Construction Standards" for the purpose of setting forth the
technical criteria to be used in the analysis, design and construction of storm drainage systems
within the City; and
WHEREAS, in 1991, the City Council adopted Resolution 1991-44, amending the Storm
Drainage Design Criteria and Construction Standards by the addition of"Construction Erosion
Control Criteria"; and
WHEREAS, in 1999, the City Council adopted Ordinance No.042, 1999, amending the
Storm Drainage Design Criteria and Construction Standards to substitute and replace the
Rainfall Intensity Duration Curve, and reaffirming, readopting and reenacting the Standards as
amended; and
WHEREAS, all new developments in the City are required to comply with the Storm
Drainage Design Criteria and Construction Standards, as amended, pursuant to Section 26-544 of
the City Code and Section 3.3.3 of the City's Land Use Code; and
WHEREAS, at a work session in December 2009, the City Council considered staff
recommendations for updating and improving the City's stormwater program and provided
feedback to staff, and
WHEREAS, one priority area for improvement identified in City Council discussions
was the development of landscape design standards and guidelines to establish and encourage a
more integrated approach for stormwater and detention facilities; and
WHEREAS, City staff has worked with stakeholders, the general public and the City
Water Board to develop and refine a proposed set- of "Landscape Design Standards and
Guidelines for Stormwater and Detention Facilities", attached hereto as Exhibit A and
incorporated herein by this reference (the "Landscape Standards and Facilities Guidelines"; and
WHEREAS, the Landscape Standards and Facilities Guidelines are aimed at facilitating
the infiltration of runoff, enhancing stormwater quality, increasing habitat value and plant
conservation, and increasing aesthetic appeal of detention facilities; and
WHEREAS, the Water Board voted unanimously in November 2009 to recommend
approval of the Landscape Standards and Facilities Guidelines; and
WHEREAS, the Landscape Standards and Facilities Guidelines were presented to the
Planning and Zoning Board at its February 2010 work session, and at that time members of the
Board offered positive feedback and expressions of support; and
WHEREAS, based on consideration of the anticipated economic, environmental and
social impacts of adoption of the Landscape Standards and Facilities Guidelines as part of the
Storm Drainage Design Criteria and Construction Standards, the City Council desires to adopt
the same in order to promote a holistic and integrated stormwater program consistent with the
City's 21st Century Utility Initiative.
NOW, THEREFORE, BE IT ORDAINED BY THE COUNCIL OF THE CITY OF
FORT COLLINS as follows:
Section 1. That the Storm Drainage Design Criteria and Construction Standards are
hereby amended to add as an addendum thereto the Landscape Design Standards and Guidelines
for Stormwater and Detention Facilities attached hereto as Exhibit A.
Section 2. That the Storm Drainage Design Criteria and Construction Standards as
amended are hereby reaffirmed, readopted and reenacted by the City Council.
Section 3. That the newly adopted addendum to the Storm Drainage Design Criteria
and Construction Standards as set forth herein shall not apply to any land development for which
an application for preliminary or final subdivision plan approval, or project development plan or
final plan approval has been filed with the City prior to April 6, 2010.
Introduced, considered favorably on first reading, and ordered published this 16th day of
March, A.D. 2010, and to be presented for final passage on the ay of April, A.D. 201 .
` V �
_ V
ATTEST:
City Clerk
Passed and adopted on final reading on the 6th day of pril,,A.D. 2010.
Mayo
ATTEST:
City Clerk
EXHIBIT "A"
Forta Collins
Co '
City of Fort Collins
Landscape Design Standards and Guidelines
for
Stormwater and Detention Facilities
November 5, 2009
PREPARED BY BHA DESIGN INC .
WITH CITY OF FORT COLLINS UTILITY SERVICES
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ACKNOWLEDGEMENTS :
STEERING COMMITTEE AND CONTRIBUTORS
Rodney Albers - City of Fort Collins Utilities
Justin Morrison - Mountain - n - Plains Real Estate Services
Michael Bello - Larkspur Homes, LLC
Les Kaplan
Stu MacMillan - Everitt- MacMillan
Jim Sell - Jim Sell Design, Inc .
Jason Claeys - Jim Sell Design, Inc .
Matt Blakely - Jim Sell Design, Inc .
Jennifer Williams Almstead - VFR
Nick Haws - Northern Engineering
Herman Feissner - Feissner Consulting, LLC
Brad Anderson - Anderson Consulting Engineers, Inc .
Steve Long - Cedar Creek Associates, Inc .
Basil Hamdan - City of Fort Collins Utilities
Dana Leavitt - City of Fort Collins Planning
Steve Olt - City of Fort Collins Current Planning
Mark Sears - City of Fort Collins Nat Resources
Angela Milewski - BHA Design Inc.
Jason Messaros - BHA Design Inc .
Glen Schlueter - City of Fort Collins Utilities
Lisa Kokes - City of Fort Collins Utilities
Louise Herbert - Landscape Architect
ACKNOWLEDGEMENTS
Page 2 of 21
Stormwater Standards and Guidelines
MEN
TABLE OF CONTENTS
INTRODUCTION 1
VISION AND GOALS 1
STRUCTURE 1
VARIANCE PROCEDURES 1
BACKGROUND 2
CONCEPTS 2
INFILTRATION VS . RUNOFF 2
HABITAT VALUE 2
STORMWATER IS AN AMENITY 3
OBJECTIVES 4
DESIGN GUIDELINES 5
GENERAL CONSIDERATIONS 5
PLANNING/SITE CONTEXT 5
LANDFORM AND SLOPES 6
PLANTING DESIGN 8
PLANT SPECIES SELECTION 8
TABLE 1 : RECOMMENDED PLANT LIST 9
PLANTING TECHNIQUES 10
IRRIGATION 12
MAINTENANCE 13
APPENDICES 14
GLOSSARY OF TERMS & CONCEPTS 14
STAKEHOLDER & OPEN HOUSE COMMENTS 16
TABLE OF CONTENTS
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City of Fort Collins
Stormwater Standards and Guidelines
INTRODUCTION
The following standards and guidelines have been • Larimer County Urban Area Street Standards
developed to inform the design and maintenance of • Army Corps of Engineers
landscaping within storm drainage and detention facilities • Neighborhood Home Owner's Association
in Fort Collins . Currently the City of Fort Collins follows Requirements
written standards for the technical design of drainage and • Neighborhood Design Review Committee
detention facilities . These facilities represent a significant Requirements
portion of open space within both public and private
developments in the city. As a result, these standards VARIANCE PROCEDURES
and guidelines will improve the overall character of our These standards and guidelines illustrate and regulate
community, storm drainage function , reduce irrigation the implementation of the concepts and objectives of
demand, improve wildlife habitat, and promote the 21st Century Utilities Initiative . Their purpose is to
maintenance of these open areas . convey these fundamental concepts, but also to foster
design innovation and collaboration between city staff,
VISION AND GOALS developers, and design professionals . Proposed designs
These standards and guidelines are part of a that illustrate the spirit and accomplish the goals, but
larger vision of both the City of Fort Collins City-Wide do not conform to these standards must be approved
Sustainability Initiative and the 21st Century Utilities by the City of Fort Collins Utilities Executive Director
Initiative . This vision is : or the Director's designee . A variance request shall be
submitted in writing prior to or as part of an application
"To inspire community leadership by reducing for development review. The variance request ( s ) shall
environmental impacts while benefiting customers, the include :
economy and society" • Identifying Issue : Identification of the standard to be
waived or varied and why the standard is unfeasible .
In order to help achieve this vision, these standards and • Alternate Design : Identification of the proposed
guidelines for landscaping have been developed with the alternative design or construction criteria .
following goals : • Comparison to Standards : A thorough description
• Promote water infiltration and water quality of the variance request and how the new design
• Habitat value and plant conservation compares to the standard .
• Improve aesthetic quality • Justification : Indication of how the proposed plan
( as varied ) advances the purpose of the standard
STRUCTURE sought to be varied equally well or better than would
This document includes background information compliance with such standard .
and describes concepts and objectives for design of
stormwater facilities to meet the goals of the 21st Based upon review of the plans and additional
Century Utilities Initiative . It includes both guidelines information submitted, the Director may approve or deny
( suggested recommendations for design improvements) the variance request . If the Director of Utilities approves
and standards ( mandatory requirements for design or the variance request, the plans will continue to be
documentation ) . The standards or requirements are reviewed and approved within the typical review process .
outlined a the end of each section . If the Director denies the variance request, the applicant
This document is intended to supplement, not shall subsequently submit revised plans in compliance
supercede, current regulatory documents which may with these Standards . The Director shall provide a written
include : response outlining the basis for all approvals or denials of
• Fort Collins Land Use Code variance requests .
• Fort Collins Stormwater Design Criteria Manual
' 11 •
Page 5 of 21
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BACKGROUND
CONCEPTS through the soil and bedrock, recharging the groundwater
The basic concepts of stormwater management are system .
not complicated . The goal is to restore the hydrological
cycle to the extent possible and to utilize the available Runoff occurs when the soil is saturated, has become
precipitation to promote a naturalized environment impermeable or when structures and impermeable
in developed areas . This requires understanding the materials are placed on the site . Runoff tends to contain
pre-development conditions so they can be an integrated silt and pollutants that require mitigation . Excessive
system in the development . runoff also contributes to adverse hydraulic downstream
conditions causing unnatural stream bank erosion and
Site stormwater design should not simply focus on basin limited groundwater recharge .
sizing and outfall rates, but should address site drainage
as an integrated multi- use hydrologic system . This system Appropriate site design promotes natural infiltration
may include detention , water quality treatments, stream resulting in fewer downstream impacts including excessive
bank erosion control, habitat creation, infiltration, energy steam flow, exaggerated geomorphology, and reduced
dissipation, and/or recreational use . The concepts stormwater capacity of natural systems .
here illustrate specific measures which affect landscape
treatments within this overall, integrated stormwater HABITAT VALUE
design approach . Historically the area that is now Fort Collins was a
short grass prairie with a large variety of plant and animal
INFILTRATION VS . RUNOFF species . Many of these species have been displaced by the
Infiltration is a natural process by which precipitation is onset of development. Natural waterways and drainage
absorbed into the soil . Depending on the local soil type, patterns are altered by development . This decreases
some of the water remains in the top layers of soil and the functionality of existing hydrologic systems . It is
is used by vegetation . The rest of the water percolates necessary to reasonably accommodate and/or reestablish
PRE-DEVELOPMENT POST- DEVELOPMENT the hydrologic systems that existed prior to development
(TYPICAL) through the site and landscape design process .
RUNOFF INCREASED
RUNOFF '
F -
DECREASED
INFILTRATION l INFILTRATION
bone
DECREASE
RUNOFF
INCREASE INFILTRATION Naturalized Planting Improved Habitat
Value
GOAL: POST - DEVELOPMENT
DESIGNED FOR INFILTRATION
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Clity of Fort Collins
Stormwater Standards and Guidelines
STORMWATER IS AN AMENITY
Stormwater facilities have a reputation for being
functional site features without natural qualities . The basic
design parameters for a detention pond design is capacity
or volume and rate of discharge . These parameters
combined with economic factors typically result in designs
that maximize the amount of stormwater detention within
the smallest possible area .
These parameters are typically accomplished by the
creation of geometric basins with calculated volume and
outflow rates, connected to site and local utilities through
standard gray concrete and steel structures . The typical
detention basin is functional as a facility, yet, provides
little or no aesthetic or habitat benefits . In many cases
detention basins of this kind detract from the overall
project image or appeal and adversely affect surrounding
properties .
Detention ponds and waterways can instead be
designed to both meet the engineering requirements and
provide an attractive diverse space . A detention pond can
serve as a multi - use area , wildlife habitat, picturesque
scene, entry experience or educational opportunity
while maintaining the necessary functions of stormwater
detention and water quality improvement . Stormwater
facilities should be considered an opportunity for aesthetic
interest and natural integration rather than solely
necessary features of a development .
E
" Front
1 • • • A • • • l - Improved Aesthetics
BACKGROUNDErr
Page 7 of 21
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OBJECTIVES
In order to achieve the overall goals, the following and showy flowers, fall leaf color, winter texture, and
objectives must be met : grasses that persist through the winter while they
provide good wildlife habitat .
Is INFILTRATION AND WATER QUALITY • Use vegetation to frame viewsheds and enhance the
Reduce excess runoff and downstream pollution by natural aesthetic qualities of the site .
increasing on -site infiltration and water quality. Maintain
the primary functions of detention ponds and stream
drainages to attenuate flows and improve water quality
while creating and improving wildlife habitat .
• Increase pervious surface area and surface
conveyance .
• Decrease flow concentration .
• Take advantage of natural processes through
bio-filtration and bio- retention .
• Manage vegetation to insure proper drainage
functions are maintained while allowing habitat values
to be expressed to the extent possible .
2 . HABITAT VALUE AND PLANT
CONSERVATION
Create and protect habitat for a diverse array of plants
and animals; birds, mammals, insects, amphibians, and
wetland plants .
• Increase plant species diversity including the number
and variety of butterfly host plant grasses, forbs, and
shrubs as well as the number of nectar plants and
shelter plants .
• Increase the number and variety of native shrubs and
trees that provide valuable cover, berries, insects, nest
sites and other resources for migratory, nesting, and
wintering birds .
• Increase the number and variety of wetland species
that provide optimal conditions for amphibian and
reptile breeding to occur.
3 . AESTHETIC APPEAL
Create a beautiful landscape that people will enjoy
and appreciate without sacrificing function and value for
wildlife and plant habitat .
• Increase the amount of shade and resting areas along
trails and open spaces while providing habitat for
wildlife and viewing opportunities for visitors .
• Use plant species that maintain their beauty in a
variety of seasons, such as a species with colorful
Page 8 of 21
Clity of Fort Collins
Stormwater Standards and Guidelines
DESIGN GUIDELINES
GENERAL CONSIDERATIONS • Residential Development — neighborhood greenbelts,
A significant portion of a developed site often must multi - purpose recreational fields * , pedestrian trails,
be used for drainage conveyance and site detention . entry features, water features, wildlife habitat,
In planning your site, consider how the storm drainage wetland/riparian amenities, community gardens * ,
facilities can contribute to the overall character of the orchards, natural playgrounds, off- leash dog play
project . areas * .
Developers and designers should consider :
• How will the stormwater facilities be designed to
achieve the goals of this document and the needs of w
the project? j ~
r. y
• How will the stormwater facilities be designed as an
amenity rather than a necessary nuisance for this �y
project?
,y Y
PLANNING/SITE CONTEXT • Business / Retail Development — Water features, entry
Obtain and understand information about site
conditions and site context before designing the features, loop trails, picnic shelters * , visual buffer to
detention facilities, including : screen service areas from public spaces, bioswale/
landscape islands, etc .
• Adjacent and regional drainage, recreational, and
open space patterns
• On -site topography and drainage conditions
• Soil conditions
• Unique natural features, amenities or views
• Aesthetic expectations
Consider how the design of drainage facilities and
detention areas can contribute to the overall plan and
adjacent developments . Collaborate with adjacent • Industrial Development — Visual buffer to screen
property developers to formulate a more effective service and loading areas, trail connections, recreation
neighborhood or regional storm drainage plan . Look for areas, etc .
opportunities to integrate storm drainage conveyance
and water quality systems into the planned development. +�
Using bioswales, linear conveyance with check dams, and 1
inverted landscape islands throughout the project will
increase distributed infiltration and can result in reduced - or
—
land dedication requirements for larger detention ponds .
Different development types will have differing needs
that can be enhanced by thoughtful design of stormwater -*
systems that can serve multiple functions. Some concepts
to consider for detention areas based on development * Structures and fences should be designed for
types include : flooding conditions .
DESIGN GUIDEL1NEJ9mL_.
Page 9 of 21
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o
LANDFORM AND SLOPES
f
Detention ponds engineered solely to meet the
minimum holding capacity of the required storm flows
generally result in ponds with uniform side slopes with
little natural character, or with vertical side walls that may
r
create unsafe conditions . Design pond slopes in a way that
they may also contribute to other goals . stow
know
If a detention pond is designed to also serve as a FIA
neighborhood recreation or athletic field, use gentle side MultimUse : • Passive Recreation
slopes to allow for easy access to the play fields . Steeper
side slopes can be designed with terraced flat areas to
serve as spectator seating . Other greenbelt amenities such
as picnic areas and pedestrian trails can be developed
adjacent to these spaces to create a neighborhood park
amenity that also serves as stormwater detention . While
gentler slopes for detention may require more land for the
pond, by combining the required pond area with required i
community uses, less land may be used for these open
areas overall .
Sports
MultimUse Basin * Detention & Passive Recreation, Trails /MultimUse Basine Detention Passive Recreation, Trails
THIS � NOT THIS
DESIGN GUIDELINES
Page 10 of 21
Stormwater Standards and Guidelines
Im
Detention ponds designed to be naturalized open and/or brush hogs . Consider that trash and debris must
space should include varied side slopes and an be regularly removed by maintenance personnel . Periodic
undulating bottom . Varied slope conditions will promote cleanup operations may also require the use of heavy
opportunities for plant diversity and wildlife habitat by equipment . If walls are used , they shall be limited to the
creating subtle changes in elevation above the average minimum required height and length needed . Ideally no
water level . Combine these techniques to create a wide more than 50% of a basin perimeter should be bound by
array of diverse soil conditions and exposures for plants walls . All walls shall be built of suitable materials matching
and animals to inhabit and " naturalize". adjacent architecture or designed into the landscape
scheme with natural stone or integral color concrete with
Design detention ponds with positive slopes ( 2% form liner.
minimum ) near the outlet to avoid standing water
and limit mosquito habitat . Manicured turf areas
that require regular mowing should also be sloped to Required Design Standards :
drain appropriately (4 : 1 Max) . However, flatter areas In all cases the following standards apply :
are encouraged to increase infiltration, but must be • No concrete trickle channels shall be used where
landscaped appropriately with wetland plants, forbs free draining soils are present ( Soil Group A, B ) .
and shrubs that do not require regular mowing and will Limit their use to areas with clayey soils ( Soil Group
tolerate wet and dry conditions . C, D) if necessary.
• Side slopes should vary and range from 4 : 1 to 20 : 1
Avoid the use of concrete trickle pans in areas with • No vegetated slope should exceed 3 : 1
well -draining soils as they reduce infiltration and promote • Landscaped areas should slope to drain ( 2%
evaporation and increased runoff. Where necessary, minimum ) or be planted appropriately so regular
trickle pans shall be designed as an integrated part of mowing is not required ( see PLANTING DESIGN
the landscape . Horizontal alignment shall complement section ) .
topographic character and be non linear. Embedded • Basin area cannot be 100% bound by walls . All
cobbles and/or boulders are encouraged . Color shall be a walls proposed for the pond perimeter are required
subtle earth tone . to have a high quality visual character (such as
natural stone or integral color concrete with form
General access is a primary safety consideration . liner) . Walls should not exceed 30" in height . Fences
Ramped access and gentle side slopes allow people and may be required for safety.
animals to evacuate the basin in the event of high water. • Provide a minimum of one entry point for regular
access by maintenance vehicles and mowers,
Access for maintenance equipment and personnel is and for occasional access by heavy equipment if
necessary for proper care and management of stormwater necessary. Provide adequate egress to allow users
facilities . Design slopes to provide appropriate access for to safely evacuate the area in the event of high
wheeled service vehicles, utility vehicles, lawn mowers water.
THIS Naturalized drainage channel slows drainage, NOT THIS Concrete trickle channel eliminates
promotes infiltration, allows for habitat infiltration and promotes
l „�r�� establishment evaporation and excessive runoff
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DESIGN GUIDELINES 7
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PLANTING DESIGN PLANT SPECIES SELECTION
There is no universal approach to landscape design for Delineate planting zones with similar characteristics
detention areas . Planting design must respond to site- and proposed function . Characteristics should include
specific stormwater functions, soil types and hydrology, slope, aspect, soil type, and moisture levels . Functions may
slopes, solar aspect, availability and type of irrigation, include wildlife habitat, recreational use, or visual amenity
habitat creation , planned uses and planned maintenance . or visual screening .
A Landscape Architect can assist with a comprehensive
plan for the landscape design for your project's open space Develop a plant list for each zone type . See TABLE 1 for a
and detention areas . The following guidelines outline sample listing of appropriate plant types .
important criteria for the development of landscape plans
for these areas .
Before finalizing planting plans and seed mixes, obtain
horticultural testing of the on -site soils where planting
will occur. Testing can be completed by the Colorado
State University Soil and Crop Sciences Department for
a nominal fee . Contact the Soil -Water- Plant Testing Lab
at http ://www. extsoilcrop . colostate . edu/SoiILab/soiIlab .
html for more information . Often planting plans must
be completed before construction activities take place,
so final soil conditions for areas to be planted are not
available at the time of design . If overlot grading is planned
to occur after the planting plans are complete, require
the contractor to incorporate 6" of topsoil from on -site or
imported source into final grading operations, and indicate
that the final seed mixes will be modified after final
grading is complete and subsequent horticultural tests are
evaluated .
Use native and adapted plants . Proper landscape design
with native plants based on a site's unique conditions can :
• Reduce or eliminate need for supplemental irrigation
• Reduce fertilizer and chemical pest control needs
• Enhance wildlife habitat
• Reduce maintenance needs
Plants should be screened for invasiveness by using
the Nature Conservancy's Nature Serve Explorer website
at http ://www. natureserve . org/explorer/servlet/
NatureServe ? init=Species
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Clity of Fort Collins
Stormwater Standards and Guidelines
MEN
TABLE 1 : RECOMMENDED PLANT LIST
TREES AND SHRUBS GRASSES
Upland Species — North and East Facing Species for Upland Slopes
Fourwing Saltbush (Atriplex canescens) Little Bluestem ( Schizachyrium scoparium )
Rubber Rabbitbrush (Chrysothamnus nauseosus) Side Oats Grama ( Bouteloua curtipendula )
Three- leaf Sumac (Rhus trilobata) Blue Grama ( Bouteloua gracilis )
Native Smooth Sumac (Rhus glabra) Western Wheatgrass ( Pascopyrum smithii )
Wood's Rose (Rosa woodsii) Green Needlegrass ( Nassella viridula )
White Snowberry (Symphoricarpos alba) Slender Wheatgrass ( Elymus trachycaulus )
Western Snowberry (Symphoricarpos occidentalis) Buffalograss ( Buchloe dactyloides )
Netleaf Hackberry (Celtis reticulate) Bottlebrush Squirreltail ( Elymus elymoides )
Sand Dropseed ( Sporobolus cryptandrus )
Upland Species — South and West Facing Alkali Bluegrass ( Poa juncifolia )
Fourwing Saltbush (Atriplex canescens) Sun Sedge ( Carex inops ssp . heliophila )
Rubber Rabbitbrush (Chrysothamnus nauseosus)
Three- leaf Sumac (Rhus trilobata) Species for Subirrigated Areas
Desert False Indigo (Amorpha canescens) Big Bluestem (Andropogon gerardii)
Winterfat (Krascheninnikovia lanata) Switchgrass (Panicum virgatum)
Yucca (Yucca glauca) Yellow Indiangrass (Sorghastrum nutans)
Alkali Sacaton (Sporobolus airoides)
Species for Moist, Well-drained Areas Green Needlegrass (Nassella viridula)
(2. 5-6 feet above high water line or one-year storm ) Western Wheatgrass (Pascopyrum smithii)
Saskatoon Serviceberry (Amelanchier alnifolia) Nuttall Alkaligrass (Puccinellia airoides)
Shiny- leaved Hawthorn (Crataegus erythropoda) Canada Wildrye (Elymus canadensis)
Wild Plum (Prunus Americana)
Western Chokecherry (Padus virginiana var. Species for Wetland Areas
melanocarpa) Prairie Cordgrass (Spartina pectinate)
Western Sand Cherry (Prunus bessyi) Canada Wildrye (Elymus canadensis)
Cottonwood Tree (Populus spp. ) Switchgrass (Panicum virgatum)
Netleaf Hackberry (Celtis reticulate) Inland Saltgrass (Distichlis spicata)
Fowl Bluegrass (Poo palustris)
Species for Subirrigated Areas Nebraska Sedge (Carex nebrascensis)
( 1-3 feet above high water line) Woolly Sedge (Carex lanuginose)
Leadplant (Amorpha fruticosa) Creeping Spikerush (Eleocharis palustris)
Redosier Dogwood (Cornus sericea) Torrey's Rush (Juncus torreyi)
Golden Currant (Ribes aureum) Baltic Rush (Juncus balticus)
American Black Currant (Ribes americanum)
Peachleaf Willow (Salix amygdaloides)
JAL_ Aim
DESIGN GUIDELINES 9
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PLANTING TECHNIQUES Drill seed specified mix in two passes, each at right
angles to each other. Drill half of the seed in each pass . If
Soil Preparation areas are too wet or steep to drill seed, broadcast seed in
Good soil is the foundation of a successful landscape . two opposite directions . Restore fine grade after seeding,
Planting areas require topsoil with appropriate levels of and cover seed to depth of 1/4 inch by raking or dragging.
organic matter. Spread imported or stockpiled topsoil to Firm seeded areas with a roller weighing maximum of 100
a minimum depth of four inches over areas to be planted . lbs . per foot of width .
For native seed areas, additional soil amendments are
not necessary. Native plants are adapted to the native Use of erosion control blankets may be needed on
soils, and the additional organic matter found in soil steeper slopes (greater than 6 : 1 ), or non - irrigated south -
amendments may instead promote weed growth . facing and west-facing slopes to reduce erosion, improve
soil moisture and seed germination . Natural fiber blankets
Sub-grade in planting areas should be loosened to a are preferred to synthetic blankets which can entangle
minimum depth of twelve ( 12 ) inches overall ( 8" of existing reptiles and amphibians in pond settings . Install erosion
sub-grade and 4" of new topsoil ) . Remove stones and control blankets as per manufacturer's recommendations .
clods that could impede planting, seeding, and mowing .
Stones protruding from the soil more than 3" should be Remaining seeded areas should be mulched to reduce
removed . Collect and legally dispose of sticks, roots, seed loss and improve soil moisture and germination .
rubbish, and other extraneous matter. Repeat cultivation Large sites without irrigation can be mulched with straw
in areas where equipment used for hauling and spreading mulch . Straw mulch should be certified weed -free hay or
topsoil has compacted the soil . Fine grade disturbed certified weed-free straw with no seed heads, crimped into
planting areas to a smooth , uniform surface plane with the seed bed after seeding has occurred . Irrigated sites can
a loose, uniformly fine texture . Grade to within the be hydromulched after seeding has occurred .
acceptable tolerances provided by the certifying civil
engineer. Roll and rake, remove ridges, and fill depressions Wetland Plantings and Subirrigated Plugs
to meet finish grades based on grading plans . Concentrate wetland plantings in areas where erosion
is anticipated or where favorable moisture zones are
Weeds thrive in soil disturbed by grading operations . likely to exist . Since planned moisture levels are difficult
Use of appropriate herbicides prior to planting can help to to predict, plant species in, above, and below their ideal
reduce the onset of noxious weeds and other aggressive zone to accommodate for both high water and low water
non-desirable plants . Apply non-selective herbicides seasons . Plants are then likely to establish in their optimal
to weeds after fine grading has occurred and prior to conditions . Since detention areas fluctuate with storm
planting. Herbicide shall be ' Round - Up' or similar product conditions, use species with wider tolerances to moisture
that will not persist in the soil and negatively affect conditions .
planting operations .
Wetland plugs may be necessary in areas that cannot
Seed Mixes and Installation Techniques be seeded due to constant inundation or saturation .
Seed mixes should be developed based on the on-site Plant plugs after drill seeding from mid - May through
soil conditions determined with the soil horticultural tests . July. Planting small plugs in the fall is less desirable due
Since detention and drainage areas have varying moisture to loss of plants to Canada Geese . Plug plantings can
conditions and slopes, develop a diverse seed mix with a be completed immediately after seeding. Subsequent
wide ecological amplitude . When multiple seed species are plug plantings are recommended after initial seed
used, they will tolerate a wide array of soil and moisture establishment when weeds are under control ( 2 -5 seasons
conditions . See TABLE 1 for a list of appropriate grass types after initial construction ) . These later plantings can be
for various planting zones . concentrated in bare areas and those areas needing
erosion control protection .
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Stormwater Standards and Guidelines
Wetland plugs may be planted 12" to 24" on center a natural habitat and reduce the cost of structured
and may need protection with turf reinforcement mats, protection measures . Seeding schedule should be per
jute or similar erosion control devices . Plugs can be seed source recommendation . Trees and shrubs should be
caged or covered with wire fabric, jute or other products planted prior to seeding .
for protection if damage by geese or small mammals is
anticipated . In areas of standing water, grids of string � ;
slightly above the water elevation can also be installed to Required Design Standards :
reduce waterfowl access to newly planted areas . In all cases the following standards apply :
•Trees and Shrubs Enlist the services of a Landscape Architect to
prepare the required landscape construction plans
Concentrate or group shrubs and woody plants into for commercial project detention areas .
beds or groups to more quickly create habitat for wildlife • Develop plant lists and seed mixes based on
and to reduce weeding, watering and maintenance horticultural testing of site soil conditions .
requirements . Select species based on the optimal • Delineate planting zones based on soil
moisture zones . Construct planting wells around each tree characteristics and function . Develop plant lists
or group of woody plants to capture natural moisture for appropriate for each planting zone .
the plants . Use organic mulch in planting beds or in tree • Use native and adapted plants .
wells to increase moisture retention and to reduce weed • provide a minimum of one entry point for regular
and grass encroachment . Avoid using weed barrier around access by maintenance vehicles and mowers,
trees an shrubs . and for occasional access by heavy equipment
if necessary. Do not block access with designed
Use shrubs and wetland plants strategically near inlets landscape features .
to soften the visual impact of these man- made structures • Stockpile and redistribute ( or import if necessary) a
without impeding storm drainage function . Avoid the use minimum of four inches of topsoil over areas to be
of exposed rip- rap . Rip- rap if used shall be a subtle earth planted .
tone color, not pink, and should be buried and integrated • Use non - persistent herbicide prior to planting to
with erosion control matting, and planting to soften
curtail weed establishment .
the visual impact and provide opportunities for habitat • Incorporate erosion control blankets and/or
establishment . Other types of less intrusive erosion appropriate mulch to reduce erosion and improve
control materials which incorporate planting materials soil moisture conditions for new plantings .
should be considered . Bio-engineered solutions are • Use wetland species in appropriate areas and pond
preferred in lieu of structural erosion control measures . bottoms likely to be too wet for regular mowing
Brush layering and use of live branch cuttings can restore and maintenance .
and protect stream banks and outFall areas while creating
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stones partially buried, broken �1"ii� �� 1 ' exposed rip-rap of uniform color and
edges, streambed appearance size, straight edges and square corners
DESIGN GUIDELINES I I
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F6rta
CollinsCo '
IRRIGATION
Since storm drainage and detention areas account
for the most significant portions of open landscaped
space in most projects, their design can greatly impact
the amount of irrigation water demand for a project .
Irrigation and landscape design should correspond to
the types of uses planned for the detention areas . Areas
planned for high pedestrian use such as recreational fields
will require higher irrigation needs to provide regular,
controlled irrigation levels . More natural areas may be
able to minimize or eliminate completely the need for
supplemental irrigation . Landscape designs are encouraged
to respond to each site's unique soil conditions and
planned hydrology to minimize or eliminate the need for
supplemental irrigation .
DESIGN GUIDELINES
Page 16 of 21
MAINTENANCE
Required Design Standards :
Weed Control In all cases the following standards apply :
The primary method of weed control during the initial � Use regular mowing as a primary weed control
establishment period (two to three growing seasons ) for method during initial establishment period .
seeded areas is regular mowing . Regular mowing helps e Limit use of chemical herbicides, and only use those
prevent weed seeds from being produced . Careful spot appropriate for conditions . Use non persistent
spraying is also acceptable, but many herbicides affect herbicides in upland areas, and aquatic approved
seedling grasses and non-target plants . Always read and herbicides near wet, wetland or water areas .
follow label directions . After the initial establishment • Suppress cattails for the first three to five growing
period , if chemical weed controls are needed in the seasons to allow less aggressive native species to
pond bottoms of wet detention areas, herbicides should establish .
be selected that have an aquatic label . Even herbicides Monitor and correct areas of erosion .
approved for aquatic use should only be used during • Limit irrigation and fertilization to that needed for
periods of dry weather and dryer conditions to reduce the plant establishment and specific designed needs .
amount of herbicide that gets into the water itself. Side Naturalized areas with native plants are adapted
slopes generally above the high water line can be sprayed to Colorado soils so should only require irrigation
with non -aquatic but non - persistent herbicides as per the during the initial establishment period , and
manufacturer's recommendations . should not require fertilization . High - use or active
recreation areas will require more regular irrigation
Cattails will generally establish in created detention and standard fertilization practices .
areas through natural dispersal . Although they are a
native species, they are often so competitive that they
become a mono-culture if not managed . Cattails should be
suppressed for the first three to five growing seasons to
allow less aggressive native species to establish .
Erosion Control
Areas of erosion should be monitored and corrected
to prevent damage to the landscape and storm drainage
structures .
Irrigation and Fertilization
Supplemental irrigation will be needed during the
initial establishment period . However, once established,
naturalized drainage and detention areas using native
plants and species appropriate for the specific moisture
regimes should not require fertilizers or supplemental
irrigation after establishment . Irrigation used during
establishment can either be reduced or eliminated
altogether. Limit the use of fertilizers in native plant areas .
In detention basins that also serve as recreation fields
or active neighborhood spaces, permanent irrigation and
more standard fertilization , aeration , and weed control
practices are appropriate to keep a more manicured
appearance .
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F6rtclCollinsf
APPENDICES
GLOSSARY OF TERMS & CONCEPTS
Base Flow — The portion of stream flow that is not runoff and Green Roof - A contained space over a building that is covered,
results from seepage of water from the ground into a channel partially or entirely, with living plants .
over time . The primary source of running water in a stream
during dry weather. Groundwater - Water that flows below the ground surface
through saturated soil, glacial deposits, or rock.
Best Management Practice ( BMP), nonstructural— Strategies
implemented to control stormwater runoff that focus on Hydrologic Soil Groups - Soil groups based on estimates of runoff
pollution prevention, such as alternative site design, education, potential . Soils are assigned to one of four groups according to
and good housekeeping measures . the rate of water infiltration when the soils are not protected by
vegetation, are thoroughly wet, and receive precipitation from
Best Management Practice ( BMP), structural — Engineered long-duration storms.
devices implemented to control, treat, or prevent stormwater Group A . Soils having a high infiltration rate ( low runoff
runoff. potential ) when thoroughly wet . These consist mainly of
deep, well drained to excessively drained sands or gravelly
Bio-filtration — The use of vegetation such as grasses and sands . These soils have a high rate of water transmission .
wetland plants to filter and treat stormwater runoff as it is Group B . Soils having a moderate infiltration rate when
conveyed through an open channel or swale, or collects in an thoroughly wet . These consist chiefly of moderately deep
infiltration basin (see Bio- retention ) . or deep, moderately well drained or well drained soils that
have moderately fine texture to moderately coarse texture .
Biological Diversity — The concept of multiple species or These soils have a moderate rate of water transmission .
organisms living together in balance with their environment and Group C. Soils having a slow infiltration rate when
each other. thoroughly wet . These consist chiefly of soils having a layer
that impedes the downward movement of water or soils of
Bio-retention — The use of vegetation in retention areas moderately fine texture or fine texture . These soils have a
designed to allow infiltration of runoff into the ground . The slow rate of water transmission .
plants provide additional pollutant removal and filtering Group D. Soils having a very slow infiltration rate ( high
functions . runoff potential ) when thoroughly wet. These consist chiefly
of clays that have a high shrink-swell potential , soils that
Detention - The storage and slow release of stormwater have a high water table, soils that have a claypan or clay
following a precipitation event by means of an excavated layer at or near the surface, and soils that are shallow over
pond, enclosed depression, or tank. Detention is used for nearly impervious material . These soils have a very slow rate
both pollutant removal, stormwater storage, and peak flow of water transmission .
reduction . Both wet and dry detention methods can be applied . If a soil is assigned to a dual hydrologic group (A/D, B/D,
or C/D ), the first letter is for drained areas and the second
Evapotranspiration - The loss of water to the atmosphere is for undrained areas . Only the soils that in their natural
through the combined processes of evaporation and condition are in group D are assigned to dual classes .
transpiration, the process by which plants release water they
have absorbed into the atmosphere . Hydrology - The science addressing the properties, distribution,
and circulation of water across the landscape, through the
Filter Strip - Grassed strips situated along roads or parking ground, and in the atmosphere .
areas that remove pollutants from runoff as it passes through,
allowing some infiltration, and reductions of velocity. Impervious surface - A surface that cannot be penetrated by
water such as pavement, rock, or a rooftop and thereby prevents
Floodplain - Can be either a natural feature or statistically infiltration and generates runoff.
derived area adjacent to a stream or river where water from the
stream or river overflows its banks at some frequency during Imperviousness - The percentage of impervious cover within a
extreme storm events . defined area .
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Stormwater Standards and Guidelines
Infiltration - The process or rate at which water percolates from gravitational settling to remove soil or rock particles from the
the land surface into the ground . Infiltration is also a general water column .
category of BMP designed to collect runoff and allow it to flow
through the ground for treatment . Siltation - A solid -liquid separation process utilizing gravitational
settling to remove fine-grained soil or rock particles from the
Metered Detention and Discharge - A system where stormwater water column .
is collected in a cistern pond and then slowly released into the
landscape beds or the storm drain in the following hours at Storm sewer system - A system of pipes and channels that carry
the rate that allows for better filtration and is less taxing to the stormwater runoff from the surfaces of building, paved surfaces,
overall community storm drain . and the land to discharge areas .
National Pollutant Discharge Elimination System ( NPDES) - A Stormwater - Water derived from a storm event or conveyed
provision of the Clean Water Act that prohibits discharge of through a storm sewer system .
pollutants into waters of the United States unless a special
permit is issued by the EPA, a state, or (where delegated ) a tribal Surface water - Water that flows across the land surface, in
government or and Indian reservation . channels, or is contained in depressions on the land surface (e .g.
Runoff , Ponds, Lakes, Rivers, and Streams) .
Outfall - The point of discharge from a river, pipe, drain, etc. to a
receiving body of water. Swale - A natural or human- made open depression or wide,
shallow ditch that intermittently contains or conveys runoff.
Peak discharge - The greatest volume of stream flow occurring Swales can be equipped with an underdrain or other man- made
during a storm event. drainage device . and can be used as a BMP to detain and filter
runoff .
Pervious - Admitting of passage or entrance . Material that
permits elements such as water and oxygen to enter and or pass Urban runoff - Runoff derived from urban or suburban land-
through . uses that is distinguished from agricultural or industrial runoff
sources.
Polluted runoff - Rainwater or snow melt that picks up pollutants
and sediments as it runs off roads, highways, parking lots, lawns, Water ( hydrologic) cycle - The flow and distribution of water
agricultural lands, logging areas, mining sites, septic systems, and from the sky, to the Earth's surface, through various routes on or
other land- use activities that can generate pollutants . in the Earth, and back to the atmosphere. The main components
are precipitation, infiltration, surface runoff, evapotranspiration,
Porous pavement and pavers - Alternatives to conventional channel and depression storage, and groundwater.
asphalt that utilize a variety of porous media, often supported
by a structural matrix, concrete grid, or modular pavement, Water table — The level underground below which the ground is
which allow water to percolate though to a sub- base for gradual wholly saturated with water.
infiltration .
Watershed - The land area, or catchment, that contributes water
Retrofit - The creation or modification of a stormwater to a specific water body. All the rain or snow that falls within
management practice, usually in a developed area, that this area flows to the water bodies as surface runoff, in tributary
improves or combines treatment with existing stormwater streams, or as groundwater.
infrastructure .
Runoff - Water from rainfall, snow melt, or otherwise discharged
that flows across the ground surface instead of infiltrating the
ground .
Sanitary sewer system - Underground pipes that carry only
domestic or industrial wastewater to a sewage treatment plant
or receiving water.
Sedimentation - A solid- liquid separation process utilizing
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STAKEHOLDER & OPEN HOUSE COMMENTS
• A landscape plan for all stormwater facilities must natural state and not manicured .
be prepared by a professionally licensed Landscape • Encourage bioswales, etc . in and around site .
Architect with experience in stormwater facility • Incentive to allow water to be treated at source in rain
design . gardens / bioswales / etc .
• List possible techniques/solutions with examples • Provide support that will lead to decrease in required
and case studies to help appease those entering into pond volumes such as narrower streets, pervious
uncharted territory ( both applicants and reviewers ) . . . pavements, etc . Currently engineering will not allow
this will help avoid the " pioneers get the arrows, and pervious pavement or bioswales
the settlers get the land" dilemma . • No pan requirements in ponds
• Along with various options, include the design • Don 't just default to Urban Drainage; allow variation
criteria to which City Staff will review against. If suitable to project type and size . Allow credit for
every applicant and design team needs to justify the developments that try several LID practices even if it
proposed solutions on their own, and spend extra can't be modeled or formulated in U . D. Let 's see if it
time and money getting Staff on board, it will serve works provided downstream not affected .
as a deterrent to implementing some of these new • How can we quantify infiltration / to allow for smaller
techniques . Obviously, the guidelines cannot account ponds?
for every potential option , and they need to remain • What plants can work in flat- bottom swales ( no
fluid to allow future solutions and innovations not yet concrete pan )
known . However, to get the ball rolling and encourage • City inspectors requiring concrete pans !
more imminent alternatives, not asking each project • Keep in mind expansive clay soils, cannot hold / direct
to 'fight the battle' so-to-speak would be a great water across them without issues .
benefit . • Different standards ( maintenance / design /aesthetics )
• Please put these boards on the website . for different uses / districts = industrial vs . retail
• More Wet Ponds, or flat bottom, because it provides • Civil Engineers tend to "engineer" a solution in the
additional volume least amount of space
• n Desi
• How do you handle clay soils ? Integrated g
• Use appropriate landscaping materials • Go from utilitarian to "aesthetic"
• If using sub drain , provide outlet • Multi use spaces included in final design
• Ponds should have concrete weir — because it provides • Need more cooperation between city departments to
a reference elevation reduce maintenance requirements ( onerous) on HOA's
• Slow H2O down to increase infiltration . • Go for the more natural look.
• Remove concrete pans to assist / allow areas to be • Materials :
more natural . Use planting in this area to build upon A . No rock?
drainage path . B . No concrete ?
• Reevaluate stormwater requirements to over store C . No vertical edges ?
H2O. D . No irrigation ? — ( native and adaptive )
• Take into account H2O uptake of plant material . • Green ( grass ) vs . Green ( money) vs . Green
• Use of injection / percolation wells to speed ( sustainable )
absorption . • Flexible aesthetics per property / project
• Combine system with pervious pavement solutions to • Distributed smaller detention
maximize usable land .
• No regional pond .
• Provide incentives for innovation .
• Savings from less storm sewer.
• How can green roofs help with the reduction / delay of • Raised landscape islands converted to depressed
stormwater discharge ? landscape islands
• Incentive to developer to allow pond areas to be in • Incentives for :
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Clity of Fort Collins
Stormwater Standards and Guidelines
A . Dispersed system • Standards vs . Guidelines
B . Water quality • Prescriptive vs . Proscriptive
• Slow down the water ! • Requirement for Landscape Architect on design team
• Regional / Neighborhood detention facilities vs . each • Combination ? If walls then upgrade
site — with fee similar to street over sizing • Engineering staff on team
A . Regional ( City) • LUCASS staff on team
B . Neighborhood • Life cycle vs . Front end cost
C . Private • Continue to promote growth and development
• Infill projects • Multiple use = multiple approaches
A . Smaller facilities • Difficult with little used areas
B . Swales with infiltration • No fertilizer unless play fields
• Linear detention keep larger ponds sizes down • No irrigation ( except during establishment)
• Inverted landscape islands in parking lots • Required ground cover
• Alternatives for wetland mitigation similar to Corp of • Context for plant types
Engineers in lieu of fee ? A . Categories for use, wetland , soil type, landscape,
• May not apply to detention ponds maintenance
• LID — encourage small ponds close to source B . Review Urban Drainage Standards
• Concentration of surface area C . New development vs . Infill / redevelopment
A . Less curb and gutter
B . More infiltration
C . * Increased surface area
D . Greenbelts conveying and slowing water
( check dams) to increase infiltration
• Native soils = little infiltration but slowing rate through
bioswales still help with down stream flows
• Tucson = standards top in nation as model
• City needs to be able to accept new ideas
A . Rocky mountain innovation
B . Infiltration ? City requires 2X capacity if case it
doesn't work
C . Include innovation process in standards
• Collaboration — encourage collaboration among project
team members and between team and city
• City to take a leadership role in new techniques
• Help developer to understand benefits . * Examples of
successful projects ?
• Example projects schematics, concepts illustrated
• Eliminate risk by having guidelines on the books
• Access for maintenance
• Mowing ( private Maintenance )
• Backhoes / Dumptrucks for sediment removal ( city)
• Partnership between private and city
• Gently sloping sod, few trees
• No walls?
• Limit walls to allow maintenance
• Underground detention ?
• How do you deal with long term maintenance ?
JAKEHOLDER & OPEN HOUSECOMMENTS
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