DHM
RESTORATION Floodways, Ponds, and Wetlands
TOWN OF BASALT RIVER RESTORATION CLEAR W RANCH WETLAND RESTORATION THREE SPRINGS STORMWATER WETLANDS JENNIE ADAIR PARK STORMWATER WETLANDS MAROON CREEK WELTANDS WETLAND RESTORATION CITY OF CHEYENNE BROWNFIELD REMEDIATION RALSTON CENTRAL PARK URBAN RIVER CORRIDOR
03-16 17-30 31-40 41-48 49-54 55-66 67-77
Water has played a significant role in DHM Design’s body of work for the past four decades. Rivers, open space, wetlands and other pristine ecosystems require detailed and conscientious planning that is rooted in ecology and inspired to promote the health and interconnectivity of our communities. From our early restoration work with the National Park Service at Sequoia National Park and continuing today with federal, municipal, and private projects, we act to honor and support the human and ecological systems at play. With the addition of an Ecological Services Director, DHM provides the highest level of ecological evaluation and planning within the confines of the firm. The following projects highlight our most recent interventions in wetlands and river systems in the West.
DOWNTOWN BASALT ROARING FORK RIVER - FLAT RIVER CORRIDOR PRONE TO FLOODING LEVEE TRAILER PARK
Since its creation in the mid 1950’s as temporary housing for Ruedi Dam construction workers, the 5-acre Pan and Fork Mobile Home Park has seen a series of high water events.
TOWN OF BASALT RIVER RESTORATION The Basalt Community Campus (BCC) represents a collaborative and comprehensive approach to achieving a number of long-standing social, environmental, economic and community goals including public access to the river, a riverfront park, redefinition of the floodplain and the transformation of a prominent downtown corner location. DHM has been retained by both the Town of Basalt and The Roaring Fork Community Development Corporation to assist with master planning and land use approvals for this five acre parcel. Proposed uses for the parcel, in addition to a riverfront park, include a 75 room hotel, mixed use retail, commercial and office, a branch location for Colorado Mountain College, and a nonprofit center to provide affordable rental space for vital community services. DHM is involved in all aspects of the process from community meetings and design to coordination with engineers and federal agencies for proposed development proposals. In the end, this project has the potential to offer the best of public/private partnerships resulting in new community based development and a riverfront park that will add immeasurably to the character and vitality of the Town of Basalt.
5 ACRES SITE INVENTORY + ANALYSIS
River stability and flood mitigation Riparian habitat and water systems restoration Gold medal fishing waters preservation
PROJECT GOALS
Riverfront park Realignment of river Redefinition of floodplain Transformation of downtown core
PROJECT TEAM
Ellsperman Ecological Services Matrix Engineering DHM Design
PROJECT SITE- core of downtown Basalt
FRYING PAN RIVER
ROARING FORK RIVER
TOWN OF BASALT RIVER RESTORATION 06
SITE - ROARING FORK RIVER - BASALT COLORADO
The project site is located in the heart of the town of Basalt. The goal of the project is to ultimately engage the river and incorporate it into the lives of Basalt residents and visitors. The intent is to restore a native river edge condition while allowing opportunities for pedestrian interaction. However, this portion of the river is not safe for kids to play in. Therefore we are targeting different uses such as fishing access spots, a boardwalk along the river edge, and the restoration of native riparian vegetation. Park elements constructed within the floodplain zone will be designed and constructed to withstand and recover from flood events. The site provides a key green space link between Roaring Fork Conservancy’s River Center, Old Pond Park, and Downtown Basalt.
TOWN OF BASALT RIVER RESTORATION 22
SITE - ROARING FORK RIVER - BASALT COLORADO
Interventions in river systems are a delicate balance, requiring careful study and planning. The placement of these few rocks several years ago resulted in the erosion of the opposite river bank in front of the library.
The new Basalt Library is located on the bank opposite of the project site. The wetlands existing between the library and the river will be preserved and enhanced, providing passive enjoyment of the natural riparian area.
TOWN OF BASALT RIVER RESTORATION 10
ROARING FORK RIVER - UNDER CONSTRUCTION
Our design team has been hired to study the hydraulics of the river. They will remove the existing levee that currently protects the trailer park from being flooded and restore the river corridor, shifting the river’s alignment to the north.
TOWN OF BASALT RIVER RESTORATION 12
Existing wetlands adjacent to the development site will be preserved. They provide crucial ecological services for the surrounding area, including stormwater management, flood control, and important bird habitat. This portion of the park will have limited human activity and be geared towards passive recreation.
TOWN OF BASALT RIVER RESTORATION 14
SITE - OLD POND PARK - WETLANDS ADJACENT TO ROARING FORK RIVER
STORMWATER CROSS-SECTION TOWN OF BASALT RIVER RESTORATION 16
CLEAR W RANCH WETLAND RESTORATION DHM is developing a master plan for this 550 acre ranch that aims for the coexistence, enhancement, and preservation of the natural character of the site. Located in a secluded valley near Snowmass, the site has a variety of diverse ecosystems including: pasture grasslands, mixed sagebrush, native grasslands, east and west facing oak brush, aspen forests, and wetlands. Portions of the site have been identified by the Colorado Department of Wildlife as primary elk production habitat within the Roaring Fork Valley. Stephen Ellsperman led the project team in developing construction drawings and USACOE permit approvals for approximately 1 mile of stream restoration as well as 15 acres of wetland restoration and enhancement. DHM is providing construction administration for all restoration activities and remains actively involved in the permit monitoring phases of the project.
550 ACRES SITE INVENTORY + ANALYSIS
Habitat and water systems restoration Elk breeding habitat
PROJECT GOALS
Ecological preservation Wetland habitat restoration and enhancement
PROJECT TEAM
DHM Design
clear w ranch CONCEPTUAL RENDERING 20
CONCEPTUAL RENDERING | COMPLETED PONDS & STREAM
1 MILE STREAM - TO BE CONSTRUCTED
CONSTRUCTED WETLANDS: 5,000 s.f.
STREAM CROSS-SECTION CLEAR W STREAM RESTORATION 22
WILLOW
WETLAND
COTTONWOOD
SITE CONTEXT - PLANTING PLAN
WETLANDS TO REMAIN
CLEAR W RANCH 24
POND IMPROVEMENTS NATIVE SPECIES PLANTINGS, FISH HABITAT, SEDIMENT MITIGATION
FISH HABITAT STRUCTURES
NATIVE SPECIES
WETLAND PLANTING
HERBACEOUS WETLAND GRASS PLANTING LAYOUT
WETLAND BENCH | POND EDGE
Water Sedge Carex aquatilis Wooly Sedge Carex lanuginosa Nebrasca Sedge Carex nebrascensis Beaked Sedge Carex utriculata Hardstem Bulrush Schoenoplectus acutus American Burred Sparganium eurycarpum Small Wing Sedge Carex micropetra Creeping Spike Rush Eleocharis palustris Arctic Rush Juncus arcticus Colorado Rush Juncus confuses Sword Leaf Sedge Juncus ensifolius Tracy’s Rush Juncus tracyii American Threesquare Bulrush Schoenoplectus pungens Blue Joint Reed Grass Calamagrostis canadensis Thurbers Fescue Festuca thurberii Manna Grass Glyceria striata
CLEAR W PONDS RESTORATION 26
HERBACEOUS WETLAND GRASSES
WETLAND PLANTING
WETLAND BENCH STAKING
CLEAR W PONDS RESTORATION 28
WETLAND PLANTING CLEAR W PONDS RESTORATION 30
THREE SPRINGS STORMWATER WETLANDS DHM Design developed a landscape masterplan as a framework for tying the Three Springs community together. As part of that effort, DHM designed and completed construction documents for 50+ acres of parks and open space that are dedicated to the City of Durango. The parks include trails that link Three Springs neighborhoods together, as well as playgrounds, basketball courts, reconstructed wetlands, native restoration areas and water quality areas. Southern Open Space and Confluence Park were constructed to treat stormwater, restore wetlands, and provide passive recreation. The wetlands, forebay, and water quality swales catch and filter run-off from the impervious surfaces created for the new community. Oil, sediment, and other contaminants are collected and treated by the forebay and wetlands before entering the larger watershed. The wetlands help protect the water quality of Wilson Gulch and the Animas River.
50+ ACRES SITE INVENTORY + ANALYSIS
Reconstructed wetlands Stormwater management Passive recreation area Parks and drainage master plan
PROJECT GOALS
Restore native areas and wetlands Manage contaminated runoff to protect Animas River water quality Create a community asset
PROJECT TEAM
Bechtolt and Russell Planning & Engineering
Nelsen Partners
DHM Design
We think of drainage systems as amenities. Bringing together engineering, ecology and recreation, we develop creative solutions that handle many functions within challenging corridors. Stormwater harvested and filtered on the surface improves water quality, sustains planting, and supports habitat.
Retail Core Springs Side basins absorb pollutants before run off enters primary channel
Forebay Surface forebay captures sediment
Interpretive Signage System designed to be on the surface as much as possible
Existing Wetland System components designed to invite people
Secondary Loop Trail Detention area designed as visual and recreational amenity
Cottonwood Shelf
Wildlife habitat created
Stone Slab Bench
Stone structures designed for people to interact with water
Detention Basin Wetland Mimics natural patterns Stone and vegetation stabilized flood channels instead of hard structure
Open Water Water regime geared to support biodiversity
Existing Wetlands Riparian Shrubs Wildlife habitat preserved
THREE SPRINGS STORMWATER 34
INTERPRETIVE EDUCATION THREE SPRINGS STORMWATER 36
REVEGETATION Bioengineering techniques were used for the revegetation, channel stabilization and wetland restoration at Three Springs. This image shows a willow log, constructed using 100% biodegradable coir fabric, topsoil with organic amendment and native willow cuttings. The mixture is rolled up into a 16� diameter log and installed between the toe of the slope and the water’s edge. Willow stakes harvested on-site were installed into the ground deep enough to get to groundwater. Through these techniques a healthy stand of willows, and critical Willow Fly-Catcher habitat, has been restored on the once disturbed site. The willows help to stabilize the slope along the edge of the channel and prevent erosion.
THREE SPRINGS STORMWATER 38
THREE SPRINGS STORMWATER 40
JENNIE ADAIR PARK STORMWATER WETLANDS The Jennie Adair Regional Stormwater Quality Project demonstrates how a stormwater and water quality extended detention basin can be designed to meet specific engineering criteria while simultaneously providing valuable wildlife habitat and beautiful public park space. Stephen Ellsperman, Director of Ecological Planning, planned, designed, and implemented this project with the owners (City of Aspen), the Aspen Center for Environmental Studies, the design team of City of Aspen, and WRC Engineering. The project was originally conceptualized as a stormwater facility that would utilize natural and engineered systems to improve the quality of water flowing into the Roaring Fork River from approximately one-third of the storm sewers in central Aspen. The primary design challenge was to develop a stormwater quality facility integrated with a large scale constructed wetland within an environmentally sensitive riparian corridor located in central Aspen. The project was a result of a long-term collaboration between the Owner and the Aspen Center for Environmental Studies, a local non-profit organization providing environmental education.
4.2 ACRES SITE INVENTORY + ANALYSIS
Constructed wetlands Stormwater conveyence system Pre-treatment sedimentation vaults Public park and interpretive signage Riparian habitat wildlife restoration
PROJECT GOALS
Expand public understanding of the importance of stormwater Stormwater management Re-establish riparian wildlife corridor
PROJECT TEAM
Stephen Ellsperman - City of Aspen Aspen Center for Environmental Studies WRC Engineering
AWARD
2008 CCASLA Design Award ALCC Presidents Stewardship Award
WETLAND CONSTRUCTION The Jennie Adair Regional Stormwater Quality Project entails two general components: an underground stormwater pipe infrastructure/conveyance system and a 2.3 acre constructed wetland. An on-line diversion system was designed using a total of three (3) pre-treatment sedimentation vaults to divert the design water quality storm event (2-year) into the vaults, while events larger than the 10 year water quality event continue to flow through the underground system to discharge into the stormwater wetland. Specific features of the constructed wetland include an ephemeral pond habitat and open water habitat with associated open water fringe wetland pond habitat. Streambank and slope protection was accomplished with the utilization of large logs, root wads, coir logs, and wattles in place of riprap. Plant material was critical to the success of the project. Cuttings and seeds of genetically important plant materials were collected and harvested prior to construction, and then propogated by a local native plant nursery for inclusion in the project.
CONSTRUCTED WETLANDS JENNIE ADAIR PARK 44
INTERPRETATION The project’s public education and interpretation component has a long term value to the environment. More citizens and visitors will gain an expanded knowledge of how stormwater gets polluted and how that polluted stormwater can enter the Roaring Fork River. Given that the river provides so much recreational opportunity, habitat value, aesthetic value, and agricultural value, every citizen and visitor to the Roaring Fork Valley is in some way vested in having the best water quality possible in the river. A small public park was also developed adjacent to the upper wetland, which includes picnic tables and opportunities for users to closely interact with the wetland edge.
JENNIE ADAIR PARK 46
The Jennie Adair Restoration Project is the ultimate example of solving complicated ecological restoration needs that intersected the most challenging of landscape situations. Through careful analysis of opportunities and constraints, the project was able to accomplish all of the critical project goals while being incredibly sensitive to a critical riverine corridor. In order to ensure that sound ecological restoration principles were carried out on the project, ecological site attributes were studied for a full year before one shovel full of soil was disturbed. A thorough understanding of the dynamic relationships between the floodplain, riparian corridor, and hydrology of the site was critical to the eventual success of this highly acclaimed restoration project.
ROARING FORK RIVER JENNIE ADAIR PARK 48
MAROON CREEK WETLANDS WETLAND RESTORATION Maroon Creek Wetlands restores natural wetland areas displaced by a local bridge construction project. A secondary goal is to provide stormwater detention for a nearby golf clubhouse and apartment project. The resulting design is a seamless blend of form and function. Maroon Creek’s natural wetlands were drained for agricultural use in the late 1800s. Today, the restored area offers valuable plant and animal habitat, and provides a natural filter system for improving runoff storm water quality for the area. Construction of the project required tight tolerances to mimic natural water flows. Genetically important plant materials were collected before construction began, propagated by a local nursery, then planted by community volunteers. Stephen Ellsperman and the City of Aspen directed all aspects of the project, including project planning, management, excavation, irrigation, construction, planting and monitoring.
14 ACRES SITE INVENTORY + ANALYSIS
Wetland Restoration Stormwater Management Fisheries Habitat Improvement Amphibian Habitat Improvement
PROJECT GOALS
Restore natural wetland areas displaced by a local bridge construction project Restore and invigorate native Narrowleaf Cottonwood Gallery Riparian Forest Provide stormwater detention for a nearby golf course and apartment complex Provide critical wildlife habitat corridor connections from Maroon Creek to confluence of the Roaring Fork River
PROJECT TEAM
Stephen Ellsperman and the City of Aspen
AWARDS 2003 CCASLA Merit Award
Land Stewardship Designation
The Maroon Creek Wetland Project included a careful examination of the riparian ecology and riverine conditions of Maroon Creek near Aspen, Colorado. Initial goals of providing constructed wetland for stormwater management quickly morphed as careful biological inventory of the site revealed that the area was both severely degraded and had significant restoration potential. The project design included provisions for reconnecting the floodplain of the project zone to Maroon Creek, utilizing the shallow water table for significant opportunity for constructed wetlands, identifying native vegetation and ensuring that it was genetically connected to the site for restoration, and finally providing a long term monitoring and management plan to ensure the project success.
MAROON CREEK WETLANDS 52
Specialized bio-engineering techniques utilized for stream restoration
Utilizing baseline inventory and reference sites in adjacent, undisturbed areas to ensure natural characteristics in restoration process.
MAROON CREEK
Utilization of natural materials (woody debris) provides a deep fabric of holistic habitat characteristics for multiple species.
MAROON CREEK WETLANDS 54
CHEYENNE, WYOMING BROWNFIELD REMEDIATION LOWER CAPITAL BASIN BROWNFIELD PROJECT The City of Cheyenne needs an adequate storm drainage system for the downtown and near west side. DHM was part of a team that helped the City win a $1 million Brownfield EPA Coalition Grant to help the community redevelop the west side into a revitalized downtown amenity. This project will incorporate essential stormwater drainage management and stormwater quality features within a park amenity and create connectivity to the Greater Cheyenne Greenway System.
30 ACRES - 7 CITY BLOCKS SITE INVENTORY + ANALYSIS
Brownfield remediation Stormwater management Park connectivity
PROJECT GOALS
Strategically shape the physical and social character of the area around arts and cultural activities following assessment and remediation of the brownfield properties.
PROJECT TEAM
Cheyenne Downtown Development Authority
Ayers Associates DHM Design
RISK OF FLOODING Flooding is a nationwide problem for our cities in the United States and Cheyenne is no different. With more development of buildings and hardscape such as roads and parking lots, the amount of stormwater run-off is increased. Currently in Cheyenne, the storm drain system is undersized for most storm events.
An efficient drainage system that is a combination of surface treatment and the existing piped system will address health and environmental concerns, incorporating both flood control and water quality measures. This map shows the lower capitol basin and delineates the areas that could possibly be affected by a 100 year flood event. Additionally, the existing Union Pacific Railroad embankment restricts the natural flow path of Capitol Basin to its historic confluence with Crow Creek.
Approximate 100 Year Flood Inundation Limited existing green space throughout the North Capitol Basin neighborhood Areas of Opportunity Improved Rail Spur : Pedestrian corridor with surface stormwater treatment
SITE MAP - CAPITOL BASIN - CHEYENNE, WYOMING
The next major storm may cost the city more than $70 million directly and more than $100 million, including indirect costs. Increasing the pipe sizes of the existing sewer system is possible but will be very expensive.
CHEYENNE BROWNFIELD 58
STORMWATER AND PUBLIC SPACE Our many years of brownfield revitalization experience have shown us that economic development blossoms when arts and cultural investments bring people into the community. This newly created centralized park and connected parkway system will preserve the historic character of the near west side while creating new vibrant public venues. HEALTH BENEFITS OF GREEN SPACE Research has proven the connection between wellness and access to nature, access to safe play spaces, to walking and biking, and to other forms of physical activity. We also know that children are healthier and happier when they play safely outdoors and experience the natural world first-hand. Art, culture and social cohesiveness have also been shown to reduce stress and improve mental and physical health. A well-designed public park can provide all of this and more. This project seeks to not only address health concerns and remove the current barriers to redevelopment, but also to consciously create a public space that actively contributes to the health and well-being of the community - now and for decades into the future.
CHEYENNE BROWNFIELD 60
CONSTRUCTED WETLANDS A constructed wetland is built to naturally treat stormwater runoff from impervious pavement. The wetland would be stepped down from the street at the lowest part of the Park. Trails, lawn areas and trees could also be incorporated tying the constructed wetland to a formal park-like setting.
STREETSCAPE WITH SURFACE DRAINAGE
BIORETENTION
BIOSWALES AND VEGETATED SWALES
An urban streetscape can have a water quality and conveyance swale meandering through the landscape strip between the sidewalk and the street. Not only does this swale allow for movement of stormwater, it also creates a buffer between the pedestrian zone and the street.
Bioretention is an engineered basin created to hold stormwater run-off and allow it to filtrate slowly. The basins are typically filled with native vegetation that is used to remove pollutants from the water.
Swales are densely vegetated shallow channels designed to move run-off slowly. Check dams may be incorporated into swales to reduce velocity and encourage infiltration.
CHEYENNE BROWNFIELD 62
REVITALIZE CORRIDOR RESTORE EXISTING STEAM PLANT CONNECT PEDESTR IAN PATHWAYS
BROWNFIELD REDEVELOPMENT Reinvestment in the heart of our community is a wise decision. Brownfield redevelopment of the west edge of downtown and near west side will leverage public funding to attract greater private investment. Brownfield redevelopment will integrate much needed stormwater drainage management for the downtown area, providing a great return on investment. Redevelopment of under-used areas can significantly increase overall property values in the area. EPA studies have shown that on average, $18.68 are leveraged for each EPA Brownfield dollar expended. Moreover, EPA studies indicate nearly eight jobs are leveraged for each $100,000 of EPA Brownfield dollars expended.
TRANSITION RAIL SPUR TO WALKABLE PEDESTRIAN CORRIDOR WITH REGENERATIVE LANDSCAPE STRIP
SITE - STEAM PLANT - CHEYENNE, WYOMING
Reusing valuable downtown space generates local property and sales tax revenues that can be devoted to streets, lighting, sanitation, greenery, police and fire. Additional jobs are generated or retained in construction, retail businesses, and arts and cultural production. As a result, new businesses are attracted to these communities.
CHEYENNE BROWNFIELD 64
INTERIOR STORMWATER ELEMENTS: RESIDENTIAL RAIN GARDEN
PARK GATEWAY
INTERIOR STORMWATER ELEMENTS: BIOSWALE TREATMENT OF URBAN RUNOFF STRENGTHEN THE URBAN FOREST: ADD TREES & SIDEWALKS ALONG EDGES
SITE - DINEEN HBLOCK- CHEYENNE, WYOMING
INTERIOR STORMWATER ELEMENTS: CONSTRUCTED WETLAND
CHEYENNE BROWNFIELD 66
RALSTON CREEK - FLOODING - ARVADA, COLORADO
RALSTON CENTRAL PARK URBAN RIVER CORRIDOR In the summer of 2010, DHM Design joined a multi-discipline planning team led by the City of Arvada for the Garrison Street Corridor. One of the goals of the team was to have a well integrated planning and design process for the park and adjacent projects. The floodplain improvements to Ralston Creek removed 90 homes from their floodplain designation by shifting the floodplain into the parkland to the south, creating a significant change to the existing park site. In order to accommodate the floodplain improvements, the existing Garrison Recreation Center and corner building were relocated to another site; existing trees within the floodplain were removed and the entire site lowered by approximately five feet. This significant change allowed the City of Arvada an opportunity to redevelop the entire park site, including the Ralston Creek Regional Trail, the Garrison St. and Brooks Dr. streetscape.
22 ACRES SITE INVENTORY + ANALYSIS
Floodplain improvements
PROJECT GOALS
Floodplain realignment Reconstruction of existing regional trail Replacement of pedestrian bridges Renovation of community park and open space
PROJECT TEAM
City of Arvada
Urban Drainage and Flood Control District
URS Corporation
DHM Design
SEPTEMBER 2013 COLORADO FLOODS
2013 FLOODING - DAMAGE AVERTED
Flooding on the front range caused Ralston Creek to breach its banks but new improvements to the Ralston Central Park Corridor kept the rushing waters contained and on course through the park corridor. Ninety homes adjacent to the park were saved from flood damage due to the recent realignment of the floodplain.
RALSTON CENTRAL PARK 70
FLOODPLAIN AND PUBLIC SPACE New park structures were designed to help minimize potential flood hazards in the future. The project includes construction of a 100 ft. span bridge on Garrison Street at Brooks Drive for increased water flow, the removal of the old buildings and facilities on the park site, realignment of the creek including a the entire park area. Excessive rain and stormwater now move more efficiently through the area and any overflow from the creek remains in the park area which has been lowered by nearly 5’ in elevation. Now, with the increased floodplain capacity of the park, the adjacent neighborhood is spared from floodwaters.
RALSTON CENTRAL PARK - UNDER CONSTRUCTION
broader, deeper channel, tree mitigation, riparian restoration, and re-creation of
RALSTON CENTRAL PARK 72
RALSTON CENTRAL PARK - UNDER CONSTRUCTION
100 YR FLOODPLAIN - BEFORE 100 YR FLOODPLAIN - AFTER
RALSTON CENTRAL PARK 74
RALSTON CENTRAL PARK 76
JOHNSON HABITAT . DENVER, CO
www.dhmdesign.com