March 23, 2007 | General

Building Soils For Storm Water Compliance And Successful Landscapes

BioCycle March 2007, Vol. 48, No. 3, p. 48
West Coast Conference Preview
Research, regulations, innovative projects and professional outreach are making the soil-water connection in Washington.
David McDonald, Sandy Salisbury and Kris Beatty
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THE SOILS for Salmon project – initiated in 1999 by the Washington Organic Recycling Council (WORC) – has been building momentum through collaboration with the Washington Department of Transportation (WSDOT), regulators at the state Department of Ecology, local governments, scientists, and green leaders in the building, landscape and development industries. Over the years, the Soils for Salmon has been building awareness – via policies, projects, research and more – about the need to restore soil life by amending damaged soils with compost. The consistent message is that soil protection and restoration are essential to restoring Northwest streams and salmon.
Builders, developers, designers, and landscapers are adopting practices that preserve soil quality on building sites and protect waterways. State and local governments are beginning to require these simple soil “best management practices” (BMPs), which include preserving site topsoil and vegetation where possible, reducing compaction, and amending disturbed soils with compost to restore healthy soil functions.
Soil improvement with compost has benefits for public health (through reduced need for pesticides and cleaner streams), summer water conservation, and long-term landscape success and ease of maintenance. But the big driver in Washington has been stormwater management. The federal Clean Water Act standards, and Endangered Species Act listings of threatened salmon species, have put regulatory force behind the urgent need to protect and restore soils in our developing region.
Background and history of the Soils for Salmon program are found in these BioCycle articles: “Organics Play Role In Salmon Recovery In Pacific Northwest,” April 2000; “Composting Advances In Oregon And Washington,” February 2001; “Organics Recycling Initiatives Spawned By Salmon Recovery,” September 2001; “Best Management Practices For Post-Construction Soils,” February 2004; and “Soil Restoration with Organics Enters Mainstream of Storm Water Practices,” April 2005. This update highlights recent developments around Washington.
Here in the Northwest, the increasing frequency of intense “100 year” storms over the last few years, and decreasing average winter snow pack, tell us that global climate change is real, and it’s here. Now, in addition to our long winter drizzles and dry summers, we need to plan for more frequent intense, tropical-like rainfall events (minimonsoons or the “pineapple express” as we call it here). We also need to plan for the possibility of multiyear low snow packs stressing our summer water supplies. (Our snow pack decreases rapidly with warming, because most of it is at lower elevations.)
It turns out that the simple soil BMPs, as part of the toolbox of Low Impact Development (LID) techniques, can play a key role in drought and flood-proofing our urbanizing region. Healthy soil grows deeper rooted, more drought-resistant landscapes, recharges groundwater, and as noted is the key to slowing and cleaning storm runoff.
On a larger, global scale, soil sequestration of carbon in large agricultural regions through soil building (organic and sustainable farming methods for building soil organic matter) is one of the essential strategies for slowing global climate change.
The clock is ticking for western Washington’s big cities and small towns to build soil BMP requirements into their local stormwater codes, and to enforce those requirements with all builders. Stormwater runoff that is collected in municipal separate storm sewers and discharged to surface waters is required to have a permit under the federal Clean Water Act. The Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES) regulations established two phases (Phase I and Phase II) for the municipal stormwater permit program.
Around the U.S. the Phase I NPDES permits – in effect since the early 1990’s – applied to big cities (Seattle and Tacoma in Washington), state departments of transportation, and large county-owned stormwater systems. Phase II permits, now taking effect around the nation, will apply to most smaller towns and counties (at least 80 smaller cities and five counties in western Washington).
With the new NPDES permits issued this February in Washington, the big cities and counties in Phase I have 18 months to adopt local regulations that comply with the state’s Stormwater Manual. The smaller towns in Phase II (the rest of western Washington) have 30 months (until August, 2009) to adopt compliant regulations.
The big news is that all these counties, cities and towns will have to adopt and enforce a Soil Quality BMP like the one in the state’s Stormwater Manual. (The Soils for Salmon team helped to write this BMP – see a summary in the sidebar, “Soil Best Management Practices – New Construction,” and full information on the website.)
The first local jurisdiction to adopt a compliant BMP was King County, in early 2005. Big cities, led by Seattle, have been working on stormwater regulations that permit the full range of Low Impact Development stormwater techniques, including soil restoration, to fit a built-out, urban landscape. A key result of this collaboration is the Low Impact Development Technical Guidance Manual for Puget Sound, assembled by the Puget Sound Action Team and Washington State University to give the “how to” for LID practices specified in the state Department of Ecology’s Stormwater Manual. (All these documents are linked from the website, These regional partners have been reaching out to smaller jurisdictions to help them apply LID methods locally, and meet their NPDES permit requirements in a local context.
Many recent projects (easy to find if you Google them) have used soil BMPs for stormwater management, landscape success, and higher public and resale values, including: Seattle’s Natural Drainage System – urban retrofits with compost amended swales; High Point public housing redevelopment project – swales, plus amended soils on whole site; and New private developments at Redmond Ridge, Issaquah Highlands, Salishan, and many more.
By summer, we’ll have case studies of many projects up on the website.
Soils for Salmon partners have kept up a dizzying pace of professional education to help the new regulations, especially soil BMPs, hit the ground. King County is in full implementation mode – they have trained building inspectors and builders, written a local guide, and are reaching out to help smaller, NPDES Phase II towns. Seattle led on recent regional professional training, and on developing the new website, with an updated state-wide Soil BMP Manual, compost calculator, cut-and-paste construction soil specifications, explanatory slide show, resources, and more. (The manual, available on the website, was originally developed under funding from Snohomish County Solid Waste, another founding Soils for Salmon member.)
Over the last few years, professional training on soil BMPs have reached several thousand builders, developers, landscape architects, engineers, planners, and landscapers around the Northwest. As we’ve said before, we’ll just keep talking until every builder in the region knows how to, and does protect and restore soil on all sites.
Another effect of the federal Clean Water Act is that all construction projects are now required to have a trained, Certified Erosion and Sediment Control Lead (CESCL) on site, who is responsible for meeting erosion and water quality standards. Our Soils for Salmon team (through great efforts by Cedar Grove Composting) has been invited to join in training builders and project managers as CESCLs. We bring our expertise in applying the recently EPA-approved erosion control methods: compost blankets, berms, and socks (see website for specs and links). In these trainings, we also briefly cover the soil protection and compost amendment BMPs, in the context of practical site grading and construction sequencing. Just since they began last August, we’ve trained over 400 builders – try this in your state!
Meanwhile, in eastern Washington, WORC members, WSU scientists and extensionists, the USDA Natural Resources Conservation Service, and local conservation districts and health departments are helping farmers learn how to build better soils. They have just completed their second Building Better Soils conference on recycling organic residues for more sustainable farming in an uncertain future. Washington State University’s (WSU) sustainable and organic farming programs, funded by the legislature through a groundswell of popular support, are researching and demonstrating farm composting and anaerobic digestion for dairy waste, compost use in plant pathogen control, sustainable bio-fuels development, and other organics reuse strategies.
David McDonald is a Resource Conservation Planner for Seattle Public Utilities. Sandy Salisbury is Region Liaison Landscape Architect for the Washington Department of Transportation. Kris Beatty is a Program Manager for King County Solid Waste Division. Other Soils for Salmon project members contributed information for this article.
IN AN EFFORT to quantify the flow control and water quality benefits of compost-amended roadside shoulders (a Low Impact Development technique known as Compost Amended Vegetated Filter Strips, or CAVFS), the Washington State Department of Transportation (WSDOT) has installed monitoring devices north of Seattle. The study is expected to help WSDOT and the Washington State Department of Ecology calibrate models for estimating how much water is detained or infiltrated in compost-amended roadside shoulders. Secondary objectives include documenting how effectively compost removes sediment, metals, phosphorus, and oil. Originally a three-year project funded by the Federal Highway Administration, a fourth year is now being projected. Two years of water infiltration data have been gathered and the third year is now being analyzed. One year of pollutant removal data has been obtained, and the second year is in progress.
The study is designed to quantify the capacity of compost to hold storm water and the ability of compost-amended vegetated filter strips to clean storm water. The study area consists of four sites: one curb and gutter control site; one grassed control site without compost; and two composted plots. A slope drain was installed to hydraulically isolate the roadside shoulder from the slope above. The compost-amended plots received 3 inches of compost tilled in to a depth of 12 inches.
Conclusions as of the end of the first water-year:
Water Quantity/Flow Control: Of the two plots with compost, one infiltrated 90 percent of the flow and the other infiltrated 50 percent of the flow. The differences in infiltration rate are because of the soils that are under the test plots. Plot 2 is on glacial till, a common soil in the Puget Sound basin. Glacial till has an impermeable layer at one to several meters depth. Plot 1, with the 90 percent infiltration rate is on variable subsoil; about 75 percent is glacial till, but the remainder is highly permeable sand and peat. At a minimum the composted areas hold 50 percent of the water that flow into them.
Water Quality: Data from an earlier study indicated a 60-95 percent removal rate for most common road pollutants. Data from this study are still being analyzed, and will be reported as available.
This research project will continue for a minimum of one more year. We will continue to study the data from the 2006 year, but it appears to show the same trends as the 2005 water year. On other projects around Washington, WSDOT has found that compost increases the germination and establishment of grass and other plants, even in arid climates. Look for a full report on this and related WSDOT studies in BioCycle, in early 2008.
Soil Best Management Practices
New Construction
o Retain and protect native topsoil & vegetation where practical
o Restore disturbed soils by tilling 2-3 inches of compost into upper 8 inches of soil
o Loosen compacted subsoil, if needed, by ripping to 12 inches depth
o Mulch landscape beds after planting
Existing Landscapes
o Till in compost when relandscaping
o Mulch beds with organic mulches
o Topdress turf with compost
Benefits to Builders, Consumers, and the Environment
o More marketable landscapes and buildings
o Better erosion control
o Easier planting
o Healthy, attractive landscapes
o Easier maintenance with less water and chemical needs
o Reduced storm water runoff, with better water quality for fish, wildlife, and people too

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