Don Knezik Rutgers Cooperative Extension Curtis Helm Stormwater Timber Creek High School October 22, 2010 Camden County Soil Conservation District
Outline What is a watershed? Where does precipitation go? Land Use / Land Cover Changes Point / Non-point Source Pollution Low-Impact Development Rain Gardens
What is a watershed? An area of land that water flows across, through, or under on its way to a stream, river, lake, ocean or other body of water. A watershed is like one big bathtub... Courtesy of Texas Watershed Stewards, Texas A&M AgriLife Extension
Hydrologic Cycle Gravity Recovery and Climate Experiment, University Courtesy of Texas of www.fgmorph.com
Where does precipitation go? 1. It can run off Courtesy of Texas Watershed Stewards, Texas A&M AgriLife Extension
Where does precipitation go? 2. It can be absorbed by plants and used for photosynthesis and other biological processes Courtesy of Texas Watershed Stewards, Texas A&M AgriLife Extension
Where does precipitation go? 3. It can infiltrate through the soil surface and percolate downward to groundwater aquifers Courtesy of Texas Watershed Stewards, Texas A&M AgriLife Extension
Where does precipitation go? 4. It can evaporate Courtesy of Texas Watershed Stewards, Texas A&M AgriLife Extension
Land Use/ Land Cover Changes Courtesy of Texas Watershed Stewards, Texas A&M AgriLife Extension
Stormwater 101 Types of Water Pollution Sources Point Source Pollution vs. Nonpoint Source Pollution
What is Point Source Pollution Stormwater 101 Comes from a specific source, like a pipe Factories, industry, municipal treatment plants Can be monitored and controlled by a permit system (NPDES)
Stormwater 101 What is Nonpoint Source Pollution? Nonpoint Source (NPS) Pollution is pollution associated with stormwater or runoff NPS occurs when runoff collects pollutants on its way to a collection system or water body NPS pollution cannot be traced to a direct discharge point such as a wastewater treatment facility
Stormwater 101 Examples of NPS Oil & grease from cars Fertilizers Animal waste Grass clippings Septic systems Sewage leaks Household cleaning products Litter Agriculture Sediment
Stormwater 101 Pollutants Found in Runoff Sediment Soil particles transported from their source Biochemical Oxygen Demand (BOD) Oxygen depleting material Leaves Organic material Toxics Pesticides Herbicides Fungicides Insecticides Metals (naturally occurring in soil, automotive emissions/ tires) Lead Zinc Mercury Petroleum Hydrocarbons (automotive exhaust and fuel/oil) Debris Litter and illegal dumping Nutrients Various types of materials that become dissolved and suspended in water (commonly found in fertilizer and plant material): Nitrogen (N) Phosphorus (P) Bacteria/ Pathogens Originating from: Pets Waterfowl Failing septic systems Thermal Stress Heated runoff, removal of streamside vegetation
Stormwater 101 Impact of Nonpoint Source Pollution Fish and wildlife Recreational water activities Commercial fishing Tourism Drinking water quality
Stormwater 101 Potential Sources of Pollutants Found in Residential Areas Nutrients: Fertilizers and septic systems Pathogens: Pet waste and septic systems Sediment: Construction, road sand, soil erosion Toxic: Pesticides, household products Debris: Litter and illegal dumping Thermal: heated runoff, removal of streamside vegetation
Stormwater 101 Why are these pollutants important to control? Sediment reduces light penetration in stream, clogs gills of fish and aquatic invertebrates, increases filling of impoundments. Nutrients act as fertilizer for algae & aquatic plants which can cause highly varying dissolved oxygen levels. At low DO levels, the aquatic life has the potential to be harmed. BOD measures the amount of organic matter that is decomposed by microorganisms which deplete dissolved oxygen. Toxics can impact life and contaminate drinking water supplies. Bacteria/Pathogens are an indicator of possible viruses present in the system.
Connected Impervious Surfaces Stormwater 101 No chance for GW recharge for stream base flow No chance for infiltration/plant uptake for improved water quality Peak flow rates and volumes can be too high for stream carrying capacity
A Solution: Rain Gardens Courtesy of City of Maplewood, MN
What is a Rain Garden? A rain garden is a landscaped, shallow depression that is designed to intercept, treat, and infiltrate stormwater at the source before it becomes runoff. Rain Gardens are planted with native plants of the region and help retain pollutants that could otherwise harm nearby waterways.
Stormwater 101
Rain Gardens for Parking Lots A rain garden is the residential version of a bioretention system. NJDEP. 2004. NJ Stormwater BMP Manual.
Bioretention System
Don Knezik Rutgers Cooperative Extension Curtis Helm Rain Garden Site Selection Timber Creek High School October 22, 2010 Camden County Soil Conservation District
What is a Rain Garden? Shallow landscaped depression that treats stormwater runoff. Designed to merge two important goals: aesthetics and water quality Can be blended into the landscape and made to look natural. Water is directed into them by pipes, swales, or curb openings.
Benefits Benefits of a Rain Garden Video (4.26 minutes)
Infiltration of runoff Provides flood control, groundwater recharge, and nutrient removal The Science Behind Rain Gardens Adsorption to soil particles Removes dissolved metals and soluble phosphorus Plant uptake Removes small amounts of nutrients Microbial processes Removes organics and pathogens Exposure to sunlight and dryness Removes pathogens NOTE: 90% of all storm events produce less than 1 inch of rain. Therefore, the key to reducing pollutant loads is to treat the runoff associated with the first 1 inch of rain (Clayton & Schueler, 1996). Sedimentation and filtration Removes total suspended solids, floating debris, trash, soil-bound phosphorus, some soil-bound pathogens
Where do Rain Gardens go? It depends on the surface you are collecting the runoff from Rooftop Driveway Road Rain Garden Rain Garden Rain Garden
Where do Rain Gardens go? The rain garden should be at least 10 feet from the house so infiltrating water doesn t seep into the foundation. Ensure adequate square footage (100 300 s.f.). Do not place the rain garden within 25 feet of a septic system. Do not put rain garden in places where the water already ponds or the lawn is always soggy. Avoid seasonably-high water tables within two feet of the rain garden depth. (e.g. 2 ½ if rain garden is 6 deep) Select a flat part of the yard for easier digging as a first option. Avoid large tree roots. http://clean-water.uwex.edu/pubs/raingarden/rgmanual.pdf
Walk the Property Identify the following Rooftop gutters and downspouts (if any) Do they discharge above ground? Are they directly connected to the road? Are they directly connected to the underground storm sewer? Existing stormwater infrastructure Curb/gutter for the parking lot or driveway Catch basins and storm sewers Look into the catch basins What is the direction of pipe flow? Open channel conveyance swales/ditches Detention basins Topography flat vs. sloped Type of existing vegetation (if any)
Rooftop Scenario Surface Area = Length x Width Drainage Area Width Length Hockman Farm, Winchester, Virginia
Drainage Area - Rooftop Scenario Drainage Area
Drainage Area - Road, Driveway, or Parking Lot Scenario With no curb Photo Credit: Rusty Schmidt Drainage Area
Drainage Area - Road, Driveway, or Parking Lot Scenario With a curb (curb cut needed) Photo Credit: Barr Engineering, Minneapolis, MN Drainage Area
Drainage Area Example Saugerties Community Center, Ulster County, NY How to find the drainage area of your site: 10 ft 50 ft Width Length Drainage Area = Width x Length Saugerties Community Center, Ulster County, New York 10 ft x 50 ft = 500 ft 2
Percolation Test 12 34 st nd rd th Hour Ruler Water should be completely drained within 24 hours Ideal percolation rate ~ 1.5 inches/ hour
Soil Test Sample the soil and send to the Rutgers Soil Testing Lab for: Nutrient analysis/ recommendations $20 ph analysis/ recommendations Percent sand/ silt/ clay or textural class $50 Optimal sand content for a rain garden is 50-70% Soil RibbonTest Roll soil into a ball in hand and see how it forms Hard ball Clay/Silt soil Soft ball Loamy soil No ball Sandy soil Gloucester County 4-H Fairgrounds But, don t worry clay/silt and sandy soils can be amended to get the preferred loamy soil texture
Size of the Rain Garden The size of the rain garden is a function of volume of runoff to be treated and recharged. Typically, a rain garden is sized to handle New Jersey s Water Quality Design Storm: 1.25 inches of rain over two hours. A typical residential rain garden ranges from 100 to 300 square feet.
Depth of the Rain Garden Between four and eight inches deep is ideal Depth depends upon the soil texture Sandy loam: great soil for a rain garden! 4-8 inch depth is fine Clay: not so great soil for a rain garden. Increase the surface area and decrease the depth. Soil amendments (coarse sand and/or compost) are recommended. 3 inch depth is fine http://clean-water.uwex.edu/pubs/raingarden/rgmanual.pdf
Rain Garden Sizing Table for NJ s Water Quality Design Storm Rain Garden Sizing Table Based on New Jersey s Water Quality Design Storm Drainage Area Size of 3 Deep Rain Garden Size of 6 Deep Rain Garden Size of 8 Deep Rain Garden 500 ft 2 200 ft 2 100 ft 2 75 ft 2 750 ft 2 300 ft 2 150 ft 2 112 ft 2 1000 ft 2 400 ft 2 200 ft 2 149 ft 2 1500 ft 2 600 ft 2 300 ft 2 224 ft 2 2000 ft 2 800 ft 2 400 ft 2 299 ft 2
Rain Garden Sizing Table for NJ s Water Quality Design Storm What if I don t want to use the table how do I determine the size of the rain garden? Drainage x NJ Water Quality Area (sq ft) Design Storm (ft) Depth (ft) = Size of Rain Garden (sq ft) Drainage Area: the impervious surface that you re collecting the stormwater runoff from NJ Water Quality Design Storm:1.25 inches of rain over a 2 hour period (1.25 inches = 0.1 feet) Depth: depends on the soil texture CLAY = 3 in = 0.25 ft SANDY = 8 in = 0.67 ft
Timber Creek High School Example Example Determine Drainage Area 35 ft x 100 ft = 3500 ft 2 Determine Depth of the Rain Garden based on Soil Texture 6 in = 0.5 ft Width ~35 ft Length ~100 ft Determine volume of runoff by NJ s Water Quality Design Storm standard 1.25 in of rain per 2 hours. 1.25 in = 0.1 ft Calculate the size of your rain garden 3500 ft 2 x 0.1 ft = 700 ft 2 0.5 ft So, the rain garden located on your school ground will be approx. 700 sq ft and approx. 6 in deep.
Determine Soil Amendments, if necessary General Soil Amendments Amounts for a 100 sq ft Rain Garden that is 6 Inches Deep Soil Amendment Coarse Sand (Bank Run Sand) Compost Fertilizer Amount for 100 sq ft Rain Garden 1 cubic yard 1 cubic yard Follow Soil Test Result Recommendations Lime Follow Soil Test Result Recommendations Gloucester County 4-H Fairgrounds
Determine Erosion Potential Will the velocity and erosion of the stormwater runoff be a problem? No Yes, erosion is possible. Address with: Grading Rocks or obstructions to slow flow Rocks to stabilize Erosion control blanket Photo Credit: RCE of Monmouth County
Determine Rain Garden Inlet How will the stormwater runoff enter the rain garden? Extended downspout/gutter Stone or concrete spillway Across lawn via a gradual slope Vegetated or stone-lined swales Diversion berm along the bottom of slope Paved surface
Determine Plant Quantity Approximate Amount of Plants Based on Future Mature Size Size of Rain Garden Approximate Amount of Plants 100 square feet 1 Small Tree (Optional) 7 Shrubs 24 Herbaceous Species 200 square feet 1 Small Tree (Optional) 14 Shrubs 48 Herbaceous Species Leonard Park, Morris County
The Parts of a Rain Garden
The Parts of a Rain Garden Inlet/ Splash Pad Berm Depression Ponding Area Depression Berm
Determine Plant Quantity Types of Plants http://plants.usda.gov Obligate Wetland (OBL), Facultative Wetland (FACW) Lowest Zone/ Ponding Area Facultative Upland (FACU), Upland (UPL) Highest Zone/ Upland Area Facultative Wetland (FACW), Facultative (FAC), Facultative Upland (FACU) Middle Zone/ Depression Area
Determine Plant Quantity Lowest Zone/Ponding Area Native Plants Marsh Marigold Caltha palustris Rose Mallow Hibiscus palustris
Determine Plant Quantity Middle Zone/Depression Area Native Plants Joe Pye Weed Eupatorium purpureum Obedient Plant Physostegia virginiana
Determine Plant Quantity Highest Zone/Upland Area Native Plants Black Eyed Susan Rudbeckia hirta Bee Balm Monarda didyma
Plant Selection Sun or shade layout Determine Plant Quantity Refer to schematics (Native Plant Society of New Jersey Rain Garden Manual)
Determine Mulch Quantity Triple-shredded hardwood mulch with no dye is used in a rain garden Mulch should be maintained at a 3 depth in a rain garden The benefits of mulch: Keeps soil moist, which allows for percolation of rain water Protects plants and makes weeding easier Minimizes erosion of the rain garden soil
Determine Mulch Quantity Amount of Mulch Required for a Three Inch Thick Layer Size of Rain Garden Approximate Amount of Mulch 25 square feet 0.25 cubic yard 50 square feet 0.50 cubic yard 100 square feet 1.0 cubic yard 200 square feet 2.0 cubic yards Triple-Shredded Hardwood Mulch with No Dye Springfield Municipal Annex Building, Union County
Determine Optional Supplies Optional Supplies Supplies may include: River rock PVC piping Deer fencing Soaker hose PVC Pipe River Rock Soaker Hose Springfield Municipal Annex Building, Union County