v>EPA United States Environmental Protection Agency Off ice of Water Washington, D.C. EPA 832-F-99-027 September 1999 Storm Water Technology Fact Sheet Vegetative Covers DESCRIPTION Soil erosion and sedimentation caused by vegetation removal, soil disturbances, changes to natural drainage patterns, or increases in impermeable ground cover are two of the primary problems associated with storm water runoff. One of the most effective ways to prevent erosion and sedimentation is to stabilize disturbed land through the addition of vegetation. This practice is referred to as "vegetative covering." Vegetative covers can be used to preserve existing vegetation and/or revegetate disturbed soils. They can provide both dust control and a reduction in erosion potential by increasing infiltration, trapping sediment, stabilizing the soil, and dissipating the energy of hard rain. One method for establishing vegetative covers is planting either temporary or permanent new vegetation. Specific practices can include applying sod to a site, or temporarily or permanently seeding the site. Sod is a strip of permanent grass cover placed over a disturbed area to provide an immediate and permanent turf that both stabilizes the soil surface and eliminates sediment loss. Temporary seeding consists of planting grass seed immediately after rough grading to provide soil protection until a final cover is established. Permanent seeding establishes perennial vegetation in disturbed areas. A second method for enhancing vegetative covering is by preserving existing vegetation. This allows a site's natural vegetation (existing trees, vines, bushes, and grasses) to function as a natural buffer zone during land disturbance activities. APPLICABILITY Vegetative covers can be applied at any site and are not restricted by the size of the site or local land uses. The type of soil, topography, and climate at the site determine the appropriate tree, shrub, and ground cover species for that particular management practice. Local climatic conditions help determine the appropriate time of year for planting. Temporary seeding is most suitable in areas disturbed by construction where the ground is left exposed for several weeks or more. Permanent seeding and planting is appropriate for any graded or cleared area where long-lived plant cover is desired. Some areas where permanent seeding is especially important are filter strips, buffer areas, vegetated swales, steep slopes, and stream banks. ADVANTAGES AND DISADVANTAGES Vegetative covering can be a relatively low-cost and low-maintenance practice for controlling dust and preventing erosion. It also adds to the aesthetics of a storm water control area. Limitations of vegetative covers as a management practice include: • Vegetative covering must be coordinated with climatic conditions for proper establishment. For example, cold climate areas have limited growing seasons and arid regions require careful selection of plant species. • An appropriate maintenance program must be implemented to ensure the optimum performance. ------- DESIGN CRITERIA REFERENCES Table 1 summarizes the design criteria for vegetative covers. PERFORMANCE Qualitatively, vegetative covers are clearly effective in controlling dust and erosion when properly implemented. The amount of runoff generated from vegetated areas is considerably reduced and of better quality than runoff from unvegetated areas. However, based on data currently available, it is not possible to quantify the water quality benefits of vegetative coverings as a BMP. OPERATION AND MAINTENANCE Several measures must be taken after seeding and sodding an area to promote successful growth. It is especially important to check and monitor an area after a rain event to ensure that the seeds and sod have not been damaged. If damage has occurred, the cause of damage must be assessed before repeating seed bed preparation and seeding procedures. Once a vegetative cover has been established, it is important to attend to the following: • Watering the sod frequently and uniformly. • Maintaining appropriate grass height for the species selected and the intended use. Performing occasional soil tests to determine if the soil is being appropriately fertilized. • Controlling weeds. Spot seeding small and damaged areas. COSTS The general base capital costs for constructing a vegetative cover average around $13,800/acre for seeding and $29,000/acre for sodding. A more detailed summary of the cost estimates for sodding and seeding is provided in Table 2. Please note that costs vary depending on regional climates and soil conditions. 1. Hennepin Conservation District, Minnesota, 1989. Erosion and Sediment Control Manual. 2. Metropolitan Washington Council of Governments, Controlling Urban Runoff, 1987. A Practical Manual for Planning and Designing Urban BMPs. 3. Minnesota Pollution Control Agency ,1989. Protecting Water Quality in Urban Areas. 4. Southeastern Wisconsin Regional Planning Commission, 1991. Costs of Urban Nonpoint Source Water Pollution Control Measures. Technical Report No. 31. 5. U.S. EPA, Pre-print, 1992. Storm Water Management for Industrial Activities: Developing Pollution Prevention Plans and Best Management Practices. 6. Washington State Department of Ecology, 1992. Storm Water Management Manual for the Puget Sound Basin. ADDITIONAL INFORMATION Hennepin Conservation District Ali Durgunoglu 10801 Wayzata Blvd. Suite 240 Minnetonka, MN 55305 International Erosion Control Association P.O. Box 774904 Steamboat Springs, CO 80477 North Carolina State University Dr. Greg Jennings 214 Weaver Labs, NCSU Box 7625 Raleigh, NC 27695 Southeastern Wisconsin Regional Planning Commission Bob Biebel 916 N. East Avenue, P.O. Box 1607 Waukesha,WI53187 ------- TABLE 1 DESIGN CRITERIA FOR VEGETATIVE COVERS Measure Temporary Seeding Permanent Seeding Sodding Preservation of Natural Vegetation Extent and Material Place topsoil as needed, to enhance plant growth. A loamy soil with an organic content of 1 .5 percent or greater is preferred. Use rapid- growing annual grasses, small grains, or legumes. Apply seeds using a cyclone seeder, drill, cultipacker seeder, or hydroseeder. Place topsoil as needed to enhance plant growth. A loamy soil with an organic content of 1 .5 percent or greater is preferred. Where possible, use low maintenance local plant species. Apply seeds using a cyclone seeder, drill, cultipacker seeder, or hydroseeder. Sod should be machine- cut at a uniform thickness of 1/2 to 2 inches. Careful planning is required prior to start of construction. Dimensions Place topsoil where needed to a minimum compacted depth of 2 inches on 3:1 slopes or steeper; and of 4 inches on flatter slopes. Apply mulch to slopes 4:1 or steeper if soil is sandy or clayey, or if weather is excessively hot or dry. Place topsoil where needed. Wherever possible, maintain existing contours. Hydraulic Divert channelized flow away from temporarily seeded areas to prevent erosion and scouring. Divert channelized flow away from temporarily seeded areas to prevent erosion and scouring. In waterways, select plant types able to withstand design flow velocity. Maintain existing hydraulic characteristics Avoid Heavy clay or organic soils as topsoil. Handbroadcasting of seeds (not uniform), except in very small areas. Mowing temporary vegetation. High- traffic areas. Heavy clay or organic soils as topsoil. Hand broadcasting of seeds (not uniform), except in very small areas. High-traffic areas. Gravel or nonsoil surfaces. Unusually wet or hot weather. Frozen soils. Mowing for at least two to three weeks. Activities within the drop line of trees. Concentrating flows at new locations. Miscellaneous Use where vegetation cover is needed for less than 1 year. Use chisel plow or tiller to loosen compacted soils. As needed, apply water, fertilizer, lime, and mulch. Incorporate lime and fertilizer into top 4-6 inches of soil. Plant small grains 1 inch deep. Plant grasses and legume 1/2 inch deep. Use chisel plow or tiller to loosen compacted soils. As needed, apply water, fertilizer, lie, and mulch. Incorporate lime and fertilizer into top 4-6 inches of soil. Plant small grains 1 inch deep. Plant grasses and legume 1/2 inch deep. Prior to laying sod, clear soil surface of debris, roots, branches, and stones bigger than 2 inches in diameter. Sod should be harvested, delivered, and installed within 36 hours. Lay sod with staggered joints along the contour. Lightly irrigate soils before sod placement during dry or hot periods. After placement, roll sod and wet soil to a depth of 4 inches. On slopes steeper than 3:1 , secure sod with stakes. In waterways, lay sod perpendicular to water flow. Secure sod with stakes, wire, or netting. Preservation of vegetation should be planned before any site disturbance begins. Proper maintenance is vitally important. Clearly mark areas to be preserved. Source: HCD, 1989. ------- TABLE 2 INSTALLATION COSTS Description Sodding Level >400 yd2 101 yd2 50yd2 Slopes 401 yd2 Seeding Mechanical Seeding Unit yd2 yd2 yd2 yd2 yd2 yd2 yd2 yd2 Acre yd2 Acre yd2 Acre yd2 Location Loganville Dubuque Loganville Dubuque Loganville Dubuque Loganville Dubuque Hollston, Hollston, Loganville Loganville Dubuque Dubuque , GA1 , IA2 , GA1 , IA2 , GA1 , IA2 , GA1 , IA2 MA3 MA3 , GA1 , GA1 , IA2 , IA2 Material $2.07 $1.15 $2.70 $1.15 $2.70 $1.15 $2.70 $1.15 $653.00 $0.14 $931 .40 $0.18 $1 ,267.21 $0.26 Labor Equipment $1.80 $0.93 $1.80 $0.94 $1.80 $0.98 $1.80 $1.23 $435.00 $0.09 $600.00 $0.12 $142.94 $0.13 $0.30 $0.05 $0.30 $0.05 $0.30 $0.05 $0.30 $0.05 $222.00 $0.05 $300.00 $0.06 $258.70 $0.24 Indirect Cost $1.68 $1.07 $1.68 $1.46 $1.68 $2.00 $1.68 $1.13 $430.00 $0.09 $497.10 $0.10 $436.23 $0.10 Total Cost $5.85 $3.20 $6.40 $3.60 $6.48 $4.18 $6.48 $3.56 $1 ,940.00 $0.36 $2,328.50 $0.46 $2,105.08 $0.73 YSost°f Jan-99 1998 Jan-99 1998 Jan-99 1998 Jan-99 1998 1998 1998 Jan-99 Jan-99 1998 1998 Comments Indirect costs include:$0.1 1 for indirect time, and $0.40 for shipping/semi load. Indirect costs include: $0.43 for indirect time and $0.40 for shipping/semi load Indirect costs include: $0.86 for indirect time and $0.40 for shipping/semi load Indirect costs include: $0.1 1 for indirect time and $0.40 for shipping/semi load pricing includes seed, fertilizer, hydromulch, pricing includes seed, fertilizer, hydromulch, $0.56 for profit, , $0.64 for profit , $0.75 for profit , $ 0.62 for profit and water only and water only Indirect costs include: $103.50 for indirect time, $332. 73 for profit, provided that equipment is available. Does not include grading. Includes straw mulch. ------- TABLE 2 (CONTINUED) INSTALLATION COSTS Description Fine Grade/Seed Push Spreader Grass Seed Limestone Fertilizer Level Areas Sloped Areas Unit yd2 yd2 1 ,000 ft2 1 ,000 ft2 1 ,000 ft2 1 ,000 ft2 1 ,000 ft2 1 ,000 ft2 Acre Acre Acre Acre Location Loganville, GA1 Dubuque, IA Loganville, GA1 Dubuque, IA2 Loganville, GA1 Dubuque, IA2 Loganville, GA1 Dubuque, IA2 Loganville, GA1 Dubuque, IA2 Loganville, GA1 Dubuque, IA2 Material $0.18 $0.26 $15.00 $15.18 $2.85 $2.50 $3.33 $2.80 $750.00 $661 .24 $750.00 $661 .24 Labor $0.12 $0.13 $6.25 $8.88 $6.25 $8.88 $8.88 $600.00 $109.26 $600.00 $222.12 Equipment $0.06 $0.24 $0.30 $54.00 $0.30 $54.00 $54.00 $139.50 $120.00 $139.50 $120.00 Indirect Cost $0.10 $0.10 $3.45 $100.82 $1.00 $98.28 $98.34 $839.50 $251 .30 $839.50 $257.83 Total Cost $0.46 $0.73 $25.00 $178.88 $10.00 $163.66 $164.02 $2,328.50 $1,141.80 $2,328.50 $1,261.19 Year of Cost Jan-99 1998 Jan-99 1998 Jan-99 1998 1998 Jan-99 1998 Jan-99 1998 Comments Includes fertilizer & lime Indirect costs include: 0.02 for indirect time and 0.08 for profit; equipment is owned and costs include straw mulch) Indirect costs include: $80.00 for indirect time and $20.82 for profit; does not include mulch Indirect costs include: $80.00 for indirect time and $12.28 for profit; does not include mulch Indirect costs include: $80.00 for indirect time and $18.34 for profit; does not include mulch Indirect costs include: $81 .00 for indirect time and $1 70.30 for profit; does not include mulch Indirect costs include: $81 .00 for indirect time and $1 76.83 for profit; does not include mulch 1 information provided by Earthscape Landscaping and Lawn Care 2 information provided by Weathers Landscape Services 3 information provided by New England Hydroseeding, Inc. ------- Wisconsin Valley Improvement Company Cathy J. Wendt 2301 North 3rd St. Wausau, WI 54403 The mention of trade names or commercial products does not constitute endorsement or recommendation for the use by the U.S. Environmental Protection Agency. For more information contact: Municipal Technology Branch U.S. EPA Mail Code 4204 401 M St., S.W. Washington, D.C., 20460 Excellence In compliance through optknal technical solutions MUNICIPAL TECHNOLOGY BRANCH ------- |