WaterRICH. What Is WaterRICH? Water Recycling, Infiltration, and Conservation for the Home. Become WaterRICH Today! Training Sessions and Workshops

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1 WaterRICH Water Recycling, Infiltration, and Conservation for the Home What Is WaterRICH? What You Get: Handbook and additional Resources Training Sessions and Workshops Consultation (1hr free!) Certification WaterRICH is a RiverLink Initiative to assist homeowners in managing rainwater. Through the program, RiverLink will provide an on-line resource designed specifically for smaller sites and private individuals. We are looking for residents in Buncombe, Madison or Haywood Counties, to become part of the WaterRICH program as our initial pilot Project! Come be the first in your neighborhood to be WaterRICH! What You ll Learn: Why Manage Water? Become WaterRICH Today! Hydrologic Cycle Site Analysis Measuring Runoff Techniques Where to for Help Terminology Contact Nancy Hodges at: RiverLink 170 Lyman Street P.O. Box Asheville, NC Nancy Hodges Watershed Resources Phone: x14 nancy@riverlink.org

2 WaterRICH How do I sign-up? Contact: Nancy Hodges RiverLink Watershed Resources Manager Nancy@riverlink.org ex. 14 WaterRICH is a RiverLink Initiative to assist homeowners in understanding rainwater management. Through the program, RiverLink will provide an on-line resource designed specifically for smaller sites and private individuals. The WaterRICH Program is designed for homeowners and residents of Western North Carolina. The Program was funded through a grant fro the Community Foundation of Western North Carolina, the Pigeon River Fund to help improve the water quality in the French Broad River. The Program is designed to assist homeowners a residents in the management of stormwater on their property with a focus to reuse, infiltrate and conserve water. Program Elements: Benefits: Workshop series - follows the chapters in the handbook 1 hour Consultation (free for the first 75 homes in Buncombe Madison or Haywood County) Online handbook and worksheets Water Use reduction Save Money Solve Drainage Issues Certification

3 The Program The Program: The Handbook is designed to walk a homeowner through a step-by-step process to learn how to manage the stormwater on there property to maximize reuse, infiltration and conservation. Along with the handbook, RiverLink offers a series of workshops to assist homeowners in this process, including workshops on site analysis, how to calculate your stormwater runoff, BMP selection and construction. The goal of the program is to increase infiltration of stormwater into the ground and the water table, reduce the use of potable water, improve water quality in the French Broad River Watershed and reduce pressure on the existing stormwater system. The Process Site Inventory Site Analysis Calculate your stormwater runoff Stormwater feature (BMP) selection Construction of stormwater feature(s) Certification Where do I start? Right here. You can download the entire handbook from the website at Then if you are interested in becoming certified call the Nancy Hodges, Watershed Resources Manager at x. 14 or Nancy at Nancy@riverlink.org. How do I sign-up? Interested in becoming certified call the Nancy Hodges, Watershed Resources Manager at x. 14 or Nancy at Nancy@riverlink.org. How and why do I do a Site Inventory and Analysis? Site Inventory and Analysis are critical steps in planning and designing your stormwater management system. It is taking stock of the existing conditions on your property. It includes social, environmental, and constructed features. It can identify problems such as erosion, drainage issues, and unsightly elements, or identify positive attributes such as specimen plants or a good view. You can follow the step -by-step process in Chapter 1-2 Site Inventory and Analysis. How do I tell how well the soil drains on my property? To determine soil porosity follow the step-by-step instructions in Chapter 2-3 Percolation Test How do I create measure the steepness of my property? To measure the slope of your property follow the step-by-step instructions in Chapter 2-2 Measuring Slope How do I calculate my stormwater runoff volume? You can learn how much rain water runs off or through your property in Chapter

4 How do I select the correct stormwater BMP? For assistance in selecting the correct BMP review the information in Chapter 1-4 BMP Selection. How do construct Berms and Swales? To build a berm and swale system check out Chapter 3-1 Berms and Swales. How do I build a Check Dam? To build a Check dam review Chapter 3-2 Check Dams. How do I construct an Enhanced Swale? You can follow the step -by-step instructions in Chapter 3-3 Enhanced Swales. How do I install French Drains? To measure the slope of your property follow the step-by-step instructions in Chapter 3-4 French Drains. How do I build a Rain Barrel or Cistern? To measure the slope of your property follow the step-by-step instructions in Chapter 3-5 Rain Barrels How do I build a rain garden? To determine soil porosity follow the step-by-step instructions in Chapter 3-6 Rain Gardens What if I want to build a Bio-retention, Wetland or install pervious pavers? We suggest contacting a profession for assistance with these specific types of stormwater BMPs, to find out more information see Chapter 4-1 Consults the Experts. Where do I find contractors or professionals for assistance? Check out our list of others who can help. Appendix C What Plants are good to use in stormwater BMPs? Check out our suggested Plant List.

5 Introduction to Stormwater Management for Residential Sites In this handbook we will introduce concepts of stormwater management and the reasons for implementing stormwater management features on a residential scale. This will include definitions of terminology and present the basis for stormwater management feature implementation. How many times have you heard, Oh, basements just get wet here, or How can I figure out the drainage issue on my property? This Guide to Stormwater Management for Residential Homes is focused on small scale and less technical, residential means of dealing with water. RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

6 Hydrologic Principles The keys to understanding how water moves on your site are observation and having a general understanding of hydrology principles. Hydrology is the study of water and how it moves through natural and built environments. The Hydrological Cycle is critical in the understanding of managing stormwater as a part of this natural cycle. Figure 1: Hydrological Cycle, source: USGS By John M. Evans USGS, Colorado District The Hydrological Cycle In the hydrological cycle rain, ice or snow falls to the ground as precipitation. This precipitation then takes one of two routes. The water can infiltrate or seep into the ground through percolation. This water is then either taken up by vegetation and trees, returning it to the atmosphere through evapotranspiration or the water seeps into the ground and moves under the ground until it reaches the groundwater table or surface water, such as a stream or lake. Precipitation can also stay on the ground surface as overland flow where it is known as runoff. This water can re-enter the atmosphere through direct evaporation. This water flows directly to our surface waters either through an engineered municipal stormwater system, or by overland flow usually in rivers and streams. When we talk about stormwater management we are focusing on how to mimic the natural water cycle prior to the development of the site. This means we are looking at how to infiltrate or harvest the rainwater from the typical storm event on the site, minimizing the runoff from your site. This is counter intuitive to the traditional practices of our past when it was favored to move water off sites as quickly as possible. In our urban watersheds we have begun to see the catastrophic changes this out-of-sight-out-ofmind concept of design has caused on our urban water cycle and stream systems. The current trend is to approach development and stormwater management with a comprehensive approach that includes both preventative, quality and control methods.

7 Hydrologic Principles The Urban Hydrological Cycle Rainwater reacts differently within the urban environment than in the natural environment. Much of this is to do with the imperviousness of the built environment. Understanding the principles of runoff volume, flow, and rate, along with drainage areas and storm size, is key to managing stormwater in an increasingly natural way. Figure 2: Hydrological Cycle Natural, Urban, Intermediary, source: Sustainable Sanitation and Water Management, Stormwater Runoff Factors Stormwater runoff is a factor of drainage area, storm size, and land cover. In natural areas the rain is attenuated by trees, shrubs, and other vegetation allowing for infiltration, evapo-transpiration, transpiration, and overland runoff. When we increase the amount of landcover that is impervious, meaning any surface that does not allow water to infiltrate patios, driveways, roofs, and roads this has direct affects on the runoff rate and volume. The runoff rate refers to how quickly water begins to concentrate and move from its point of origin. Prior to development vegetation intercepted rainfall, slowing runoff naturally due to the roughness of lower vegetation and cover from trees and shrubs. Impervious surfaces often do not provide similar roughness nor the ability for infiltration, therefore increasing the runoff rate. Runoff volume is the quantity of runoff for a given site. With development and the increase in impervious surfaces, the vegetated un-compacted soil and natural depressions in the landscape which allowed for infiltration are removed and result in an increase in runoff volume. Therefore, as impervious surface increases the rate and volume of runoff also increases. This creates what we call flashy runoff events, where water moves more quickly and in greater volume from a site. As a result of this is we find increased erosion, reduction in infiltration and groundwater recharge, and degradation of our streams. Urban streams receive stormwater through the storm drainage system, which is a series of pipes that direct the water to the stream, usually without any water quality treatment. The runoff velocity increases as the rainwater flows through the stormwater system, this water then rushes from the pipe into an urban stream increasing erosion and degradation. As stewards of our water resources we hope to improve residents understanding of stormwater and how it effects our environment. This program will assist you in this understanding and designing features which help improve water quality and increase infiltration, moving stormwater management to a more sustainable system.

8 Hydrology as the Integrating framework for the site How Do I Start?? Start with observations: We begin with observation. Many of us overlook the importance of understanding how water flows on or through our property. Knowing this will give clues to help determine how to solve issues, or make improvements. When it rains observe: Where water goes Where it collects What your gutters are doing (if you have them) Where it drains from and to where What is working? Where are there problem areas? Where do you have wetness in your basement or along your foundation? Where are the storm drains around your property? Do you have under drains, if so where and are they functioning properly? When it s dry observe: What areas dry more rapidly than others Sun patterns Are your gutters clean? Note significant vegetation, trees etc. Note slope (the lay of the land) do you have steep areas? Flat areas? Soils (we will discuss this in more depth in the property evaluation section) Where are the storm drains around your property? There are numerous resources to assist in evaluating your property. These systems are meant to be accessible to everyone but they can still be overwhelming because of the large amount of information they contain. If you have trouble using these resources, look for classes held by RiverLink, AB-Tech and University Extension that offer help with site evaluation techniques. RiverLink has also included these resources with a step-by-step guide in the site inventory and analysis chapter of the WaterRICH handbook.

9 Site Inventory and Analysis MATERIALS Scaled Map of Site Site Inventory is taking stock of the existing conditions on your property. It includes social, environmental, and constructed features. It can identify problems such as erosion, drainage issues, and unsightly elements, or identify positive attributes such as specimen plants or a good view. Social elements identify how people use and move through the site, such as typical paths of travel or gathering spaces. Environmental elements include aspect, wind and sun patterns, plant communities, and noise issues. The constructed components include utility lines, buildings, sidewalks, driveways and decks or patios. It is also important to note the patterns of water movement during rain events, noting the severity of the storm to help identify opportunities to use what s working and mitigate what s not. Colored pens or pencils Slope Measuring tool Calculator Measuring tape Ruler Trace paper For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

10 How to Perform a Site Inventory STEP 1: Scaled Map A. Scaled map of your property can be obtained in a few ways. 1. You may have received a plat or survey of your property in the closing of the property; either of these documents are the best option to use. Note: if you have only one copy, either scan it to an electronic file, or overlay trace paper to make comments and denote features. 2. You can obtain an aerial map of your property online at either the Buncombe County website Figure 2: Aerial from GIS or the City of Asheville website. Figure 1: Property Plat STEP 2: Information Gathering There are numerous resources to assist in evaluating your property. These systems are meant to be accessible to everyone but they can still be overwhelming because of the large amount of information they contain. If you have trouble using these resources, look for classes held by RiverLink, AB-Tech and University Extension that offer help with site evaluation techniques. The City of Asheville Geographical Information System (GIS) id=1782&ekmensel=22_submenu_0_link_3 mapwnc-steep Slope Tool: Enter PIN, address or zoom to site and than Press RUN CALCULATION button and the website will generate the average slope across your site, and specify any restrictions or regulations which apply. Standard GIS: Enter the property PIN, address or zoom to site. On the left side of the screen, you can click on additional information such as, contours, FEMA flood mapping, streams, sewer lines, etc. Buncombe County GIS Click on I agree (to the disclaimer), it will take you to: where you can enter the property PIN, address or zoom to site On the left side of the screen, you can click on additional information such as, contours, FEMA flood mapping, streams, sewer lines, etc.

11 Site Inventory STEP 2: Information Gathering Madison County Geographical Information System (GIS) Click on Image to go to Online Mapping. Do a quick search by your address or PIN to find your property. On the left side of the screen, you can click on additional information such as contours, FEMA flood mapping, streams, sewer lines, etc. Henderson County GIS At the top on the screen you can choose which layers to view Transylvania County GIS Press the magnifying glass with the? to use the search by Address or PIN function. On the left side of the screen, you can click on additional information such as contours, 2007 flood data, and water and sewer lines, etc. Haywood County GIS Search by your address or property PIN. On the left side of the screen, you can click on additional information such as, contours, soils, streams, and sewer lines, etc. Soils Information Any County or Municipality Click on GREEN Button that says START WSS Under Quick Navigation enter your address with city and state click view Above the map there are 2 buttons that say AOI. Use either to define your area of interest (AOI), or your property Click on Soil Map Tab to find out the soil types on your property, click on name of soil type and a description will appear in another window. Under the Soil Data Explorer Tab you can find out much information on your soils and appropriate uses. In the Soil Properties Tab within the Data Explorer you can view additional information, including Hydrological Soil Group for your soils, or depth to bedrock or other soil restrictive layer. Click view rating for information to appear on map

12 Site Inventory Figure 3: Example of Site Inventory STEP 2: Recording Site Data A. On the scaled map denote the following Social, built and environmental factors. Include elements you favor as well as the issues. Elements to include Social: How people and animals move through the site Proximity to other elements Privacy Constructed: House and building (usually on plat but add any additions) Sheds Garages Animal shelters Decks and patios Sidewalks Driveways Play equipment, fire pits/rings, and social gathering places Fences Have your utilities marked Water Line Electrical Line Cable Gas Line Sewer Line Wells Septic fields Propane or Oil tanks Rain Barrels or Cisterns Environmental: Aspect/ Exposure of the site (which direction the slope faces) Soil type Sun/Shade locations Slope (note the steepness, (percent grade) and extent of grade changes, note where grade changes) Note high spots and low spots Erosion (note location, square footage, severity, depth of ruts, extent of problem) Moisture/Water Issues Roof, sidewalks, street, driveway Note high spots and low spots Ponding water Plants (existing, specimen, invasive, misplaced, declining or unhealthy)

13 Site Analysis STEP 3: Analyzing your information After all inventory has been taken, it is important to process the information gathered, as well as think about future developments or uses. Begin thinking about how you use the space and the elements that are important to you. Ask yourself how you want to use the site. See Questions to Consider. Return to your inventory map with your design elements in mind. Begin examining the inventory and thinking about how all the elements could fit together. Draw on the map areas for future or changing uses, design elements, issues, and opportunities. Refer to Chapter 1: BMP Selection for assistance in selecting areas for water features and infiltration opportunities. QUESTIONS TO CONSIDER Are there special areas, or just areas you love to be in for one reason or another (i.e., shade, privacy, etc.)? Are you looking to expand your home, outdoor living space, or driveway in the future? Are you looking to add specific elements to your outdoor area, such as a playground, fences, fire pits or water features? Are any trees or vegetation going to be removed? Where are the best places for infiltration? Where do you have impervious surfaces and how do you route the runoff to infiltrate?

14 Calculating your Stormwater Runoff MATERIALS: Scale Map of property Ruler Calculator Knowing how much water runs off or through your property is critical to design and implement any stormwater feature correctly. In order to calculate this volume you will need a scaled plat or drawing of your property with all impervious surfaces visible. Let s get started! For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

15 Calculating Stormwater (Runoff) Volume Helpful Conversions feet = 1 inch 0.01 meter = 1 cm 1 cubic foot = 7.48 gallons 1 cubic meter = gallons Runoff is precipitation that flows over the land surface and is not absorbed into the ground. In urban areas runoff is high because impermeable surfaces like rooftops, paved roads and parking lots abound. This runoff moves quickly off site through stormwater drains that usually funnel directly to streams. This helps to eliminate standing water that can cause poor health conditions and roads stay clear during storms but it does not allow water to infiltrate into the water table. In other words, the water doesn t hang around long enough to water your vegetable garden. You can change that by implementing any of the many stormwater management techniques described in this guide, but how much water can you expect to harvest? In a given storm event the amount of runoff depends on many factors, making precise calculations complicated, but a rough estimate is easily obtained by using runoff coefficients. In this method, runoff is calculated by multiplying the surface area by a coefficient (Table 1) that estimates the conditions of the particular conditions. This is then multiplied by the depth of rainfall to obtain a volume of runoff. To make the calculation easier you can assume that rainfall depth comes in units of 1 (1in or 1cm etc.), that way you ll know, for instance, how much runoff you ll have per inch of rainfall. Here s the equation: Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Table 1: Runoff Coeficients Soil Groups A and B are sandier and Soil Groups C and D are more clayey. These soil classifications would be found in a county soil survey available at any Soil and Water Conservation District office or North Carolina Cooperative Extension center. Land Use/Cover 100% impervious (parking lots, rooftops, paved sidewalks or patios) Open space with grass cover <50% Open space with grass cover 50% to 75% Open space with grass cover >75% Woods in fair hydrologic condition Soil Group A Soil Group B Soil Group C (Table adapted from USDA-NRCS Curve Numbers, 1986) Soil Group D Residential lot (1/4 acre) Residential lot (1/2 acre) Residential lot (1 acre) Here s an example of how it works: Step 1: Assess Site Conditions In this example we will use a 200 ft 2 patio Step 2: Obtain Runoff Coefficient Using the provided table (Table 1), look up the runoff coefficient that most closely resembles your site. In this case it is Step 3: Do the Math Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Volume Runoff = 200ft 2 x 0.98 x 0.083ft = 16.3ft 3 Note: Make sure that Surface Area and Rainfall Depth are in the same units. It doesn t matter what you use, just stay consistent -- measurements in feet or meters are generally easiest. Step 4: Convert if Necessary Most people have trouble thinking about water volume in cubic feet so we will convert to gallons multiplying by 7.48gal/ft 3. Volume Runoff = 16.3ft 3 x 7.48 gal/ft 3 = gallons

16 Stormwater Feature Selection Completing a site Inventory and Analysis will assist greatly in determining the appropriate BMP options for your property. Stormwater features can be divided into five (5) categories based on their primary function, including retention, infiltration, detention, wetland and filtration devices. The major factors in selecting stormwater features are pollutant treatment needs, physical characteristics of the site, and environmental and neighborhood factors. THINGS TO CONSIDER: Slope Pollutants Stormwater Quality Volume Soils Impervious surfaces Aesthetics Regulations For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

17 Factors in Selecting BMPs Environmental Factors The first step in selecting your BMP features is to review the stormwater runoff volume for the specific site to determine the need for runoff rate control and volume control. In residential developments there are not requirements for reducing rate or volume of runoff from a site. Yet, as WaterRICH citizens we are looking to return the hydrology of the site towards its undeveloped natural state. In the BMP selection matrix you will find categorizations for the specific BMPs within this manual. Secondly, we need to determine water quality control measures. Residents are not required to treat stormwater from a residential lot. Examine the site analysis and determine which pollutants you wish to be treating. In some areas, you may be looking to simply infiltrate stormwater runoff. If you elect simply to have infiltration of stormwater, this runoff should be sourced from natural areas which are relatively free of synthetic chemicals. Water from the roadway, driveways, roof, fertilized vegetation, or areas where pesticides have been used should be treated prior to infiltration. There are some specific pollutants of concern that we may need to treat in the residential environment. These include fertilizers from lawns, landscapes and vegetable gardens, road or driveway runoff that could carry oils, hydrocarbons and heavy metals, animal waste, sediments, detritus, asphalt grit associated with roof shingles, or heavy metals from metal roof surfaces. Pollution builds up in various ways and is generally a function of dry period, rainfall event, and runoff volumes. As these factors increase the higher the pollutant content. Table 1: Pollutants and Sources Stormwater Pollutant Sources Related Impacts Nutrients: Nitrogen, Phosphorus, various others Sediments: Suspended in the water and deposited Animal waste, fertilizers, failing septic systems Construction sites, bare soil, road sanding, eroding banks Algal growth, reduced clarity Increased turbidity, reduced clarity, deposition of sediment, lower dissolved oxygen Organic Materials Leaves, grass clippings, compost, brush Oxygen deficit to receiving waters Pathogens: Bacteria and Viruses Hydrocarbons: Oil and Grease, PAHs Metals: Lead, Copper, Cadmium, Zinc, Mercury, Chromium, Aluminum Pesticides: PCBs, Synthetic Chemicals Animal waste, livestock, failing septic systems Automobile wear, waste oil, emissions and fuel leaks Wear of automobile brake linings and tires, emissions and fuel leaks, and metal roofs Herbicides, insecticides, fungicides, etc. Human health risks Water toxicity, sediment, and bioaccumulation through the food chain Water toxicity, sediment, and bioaccumulation in the food chain Water toxicity, sediment, and bioaccumulation in the food chain Chlorides Road salt, uncovered salt storage Toxicity of water columns and sediment Trash and Debris Litter washed through storm drain networks Degradation of the beauty of surface Adopted from Minnesota Urban Small Sites BMP Manual waters, threat to wildlife

18 Factors in Selecting BMPs Physical Factors The physical factors which determine the selection of stormwater BMPs include soils, depth to the water table, drainage area, areas of concentrated pollutants, slope of site, and the area required. These are all elements you should have reviewed in the site inventory and analysis section of this chapter. This section will assist you in finding much of this information. Much of the information above can be located on the Internet, yet it is only specific to a certain scale, specifically when we examine our soils. These are generally mapped at the 1:12,000 scale and therefore, you may find much variability in the soils on your property. It is important to examine your site in detail, through both resources on the web and site observation. Percolation tests are one of the best ways to determine the porosity of soils at specific locations within your property. Determining your drainage area and therefore the potential volume of runoff onto and off your site is critical in understanding the scale of stormwater features and the available options. Typically the lower you are in the watershed, the more water and pollutants you have to contend with. A referral (to mitigate the failure) resident in Atlanta designed and built a dry streambed to manage the water running from the road onto her property. Within a month of the beautiful feature being completed, much of the stone washed into the neighbor s drainage due to the lack of sizing for the amount and velocity of water flowing from the road. We want to prevent this possible oversight prior to construction. Community In any design or modification the environmental, social and community factors need to be assed to assist in selecting an appropriate feature. These factors include existing and future elements such as playground areas, patios or pathways. Many of these you examined in the site Inventory and analysis process. In addition (if you didn t already), weighing the maintenance requirements and community acceptance of a given practice will help in the selection process. In this area we have a mix of acceptance levels of any given feature, these are based on visual appeal and nuisance problems. General market and preference surveys have been drawn upon to build overarching opinions to base of perception. Figure 2: Run-off analysis

19 Runoff BMP Class BMP Rate Control Volume Control Berms and Swales Infiltration Basins Trench Rain gardens Environmental Factors Water Quality TSS Nurtients Metals Fecal Coliform Stormwater Feature Selection Matrix Hydroloic class Soil Considerations Physical Factors Water Table Max Slope Lot Size Area required Concentrated Pollution Community Factors Acceptance Maintenance Cost Moderate Moderate High High High Moderate 3 ft. above 10% < 5 acres Moderate Yes Moderate Low Low Moderate A or B preffered Moderate Moderate High High High Moderate C dificult may need 3 ft. above NA < 5 acres Moderate No Moderate Low Low Low Moderate Moderate High High High Moderate amending D 3 ft. above not recommended 2% < 5 acres Low No High Moderate Low none Moderate Moderate High High High Moderate 3 ft. above NA < 1 acres Moderate No High Low Low High Habitat Value Wetland Filtration Stormwater wetland Wet Swale Bioretention Filter Strips Permeable Pavers Check Dams Dry Swale High Moderate High Moderate Moderate High Any soil if below water table, if above the water table NA NA < 2 acres Moderate Yes High Low Low High Moderate Low High Moderate Moderate Low preffer D or C soils, liners 3 ft. above 4% < 5 acres Low Varies Moderate Low Low High available Moderate Moderate High High High Moderate any soil type 3 ft. above NA < 5 acres High Yes Moderate High Moderate High Moderate Moderate Moderate Low Low Low any soil type 3 ft. above 3% < 5 acres High Yes High Low Low Low Same as Infiltration devices Moderate Low Moderate Low Low Low 3 ft. above 5% < 5 acres NA Varies High Moderate High Low (see above) Moderate Low High Moderate Low Low NA NA NA < 5 acres NA Varies Low Moderate Moderate Low Moderate Low High Moderate High Low any soil type 3 ft. above 4% < 5 acres Moderate Varies Moderate Moderate Low Moderate Retention Rain Barrels/Cisterns High High Moderate Low Low Low any soil type NA NA < 5 acres Moderate No High Moderate Moderate High None

20 A-Frame Levels: Build and use your own Sometimes you will decide that you need to stop or slow water running down a slope. Whether you want to build a retaining wall or an earthen berm, you ll need to make it level so that water doesn t build up in some places and not others. This means that you will need to mark a level line across your slope- this line is called a contour. The job can be made a lot easier by using an A-frame level, and it s easy to build. MATERIALS 3/8 x2 x36 pine craft board (2) 3/8 x2 x26 pine craft board Power drill 3/16 drill bit 5/64 drill bit 10-24x1 ¼ machine screws (4) wing nuts (3) regular nut #212x15/16 eye screw 3ft string Plumb bob (or other weight such as a fishing sinker). For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

21 Construct your own STEP 1: Drill Holes A. Using the 3/16 drill bit, drill a hole through the center, 1 in from each end of the smaller 3/8 x2 x26 pine craft board. B. Next, drill a hole through the center, 9 in from one end of both of the longer 3/8 x2 x36 pine craft boards. You can see the hole positions in Figure 1. Loosely bolt (using the machine screws and wing nuts) the 3/8 x2 x36 pine craft Figure 1: Hole Position boards to the 3/8 x2 x26 pine craft board, then overlap the undrilled ends of the 3/8 x2 x36 pine craft boards (Figure 2). Figure 2: Overlap Boards C. Lastly, carefully drill two holes though both overlapped boards at the same time (Figure 3). It isn t important exactly where the two holes are so long as they go through both boards and are far enough from the edges not to break through. You are making two holes so that the A-frame cannot easily change shape. STEP 2: Temporarily Assemble Frame Figure 3: Holes through Overlapped ends A. Use two machine screws through the holes you just made to fasten the overlapping boards together (Figure 4). Use one wing nut and one regular nut (Figure 5). You are using wing nuts so that you can take it apart enough to fold it for storage. Figure 4: Screws through overlap Figure 5: Wing and regular bolts

22 Construct your own STEP 3: Placing Eye Screw A. In this step you will attach an eye screw to the top of the A-frame for the plumb bob to hang from. Mark a spot ½ down from the point where the boards overlap (Figure 6). Figure 6: Eye screw location B. Unscrew the overlapped boards and drill a small hole at the place you just marked, about ½ deep (Figure 7). This is called a pilot hole. Figure 7: Drill pilot hole C. Now screw the eye screw into the pilot hole. You can use a drill bit to make turning easier (Figure 8). Figure 8: Sink eyescrew D. Sink the eye screw fully into the board so that only the loop is showing (Figure 9). Figure 9: Eye screw facing forward E. Now you can screw the overlapped boards back together (Figure 10). Tighten all screws. Figure 10: Eye screw in final position

23 Construct your own STEP 4: Attach Plumb Bob A. Tie one end of the three foot string to the eye screw (Figure 11). B. Tie the other end to the plumb bob; you want the plumb bob to hang past the bottom rung but not touching the ground (Figure 12). Note: You can use anything as a plumb bob. A fishing weight was used here but even a rock will do as long as you can firmly attach it and it is heavy enough to pull the string tight. Figure 11: Attach string to eye screw Figure 12: Attach plumb bob C. Cut away any excess string. Your A-frame should now look like Figure 13. STEP 5: Calibration Before you can use your level you need to calibrate it by finding the center point. Set the frame on a non-level surface. Figure 13: Finished A-Frame The first leg is in position A and the second leg is in position B (Figure 14). Mark where the plumb line comes to rest with a dotted line. Now flip the A-frame around so that the first leg is where the second leg was (position B ) and the second leg is where the first leg was (position A ). Again, mark where the plumb line comes to rest with a dotted line. You should now have two dotted lines. Measure halfway between these lines and mark with a heavy solid line; this is your center line. Now any time the plumb bob hangs over the center line, you know you re level! Figure 14: Calibration

24 How to Use an A-Frame STEP 6: How to Use Your A-Frame to Find Contours You can use your new A-frame level to mark a contour across a slope. A. Begin by placing the A-frame where you want to start the contour line. Adjust the second leg of the A-frame until the plumb bob rests over the center line and then mark where the two legs for the A-frame rest (positions A and B in Figure 15). Figure 15: Starting position B. Now move the A-frame so that the first leg is where the second leg was. Adjust the second leg of the A-frame until the plumb bob rests over the centerline, just as you did before, and mark where the second leg rests (position C in Figure 16). Move along the slope in the same pattern until you ve marked a contour as long as you need (Figure 17). Easy! Figure 16: Starting position Figure 17. Marked contour

25 Measuring Slope Controlling storm water runoff depends largely upon how much, and in what direction, the ground slopes. Direction can be measured using a compass, but if you just want to know which way your runoff is going (for instance, toward or away from your house), turn on the hose and sprinkle the area until you can see where the water runs. SUPPLIES Measuring tape or yardstick String Line Level (costs about $2, see photo in STEP 2) Screwdriver Hammer Tall Stake (I used the broken handle of a rake) For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

26 Measuring Slope STEP 1: Setup Using the hammer, pound the stake firmly into the base of the slope. Make sure the stake is straight up and down. Tie the string to the shaft of the screwdriver and then push into the ground at the top of slope (Figure 1). Figure 1: Set-up STEP 2: Leveling Now that the string is anchored to the ground, pull the string tight between screwdriver and the stake. Use the level to make the string level. When the string is level, tie it to the stake. Figure 2: Leveling STEP 3: Measuring Measure the height of the string at the stake by using a measuring tape or yard stick. Next measure the length of the string from the stake to the screwdriver. Figure 3: Measuring STEP 4: Calculation Calculating slope is easy- it s the height of the stake to the string divided by the length of the string, multiplied by 100: Example: Height=35 in. String Length=105in Figure 4: Set-up diagram with length and height marked

27 Percolation Test A Percolation test will help in determining the permeability of the site at a specific location. Since the Natural Resources Conservation Service (NRCS) soil survey data is typically completed at the large scale of 1:12,000, a percolation test can tell you more about how the soil on your individual site will drain. You may want to complete more than one percolation (perc) test, given different elements and soil variability on a given site. SUPPLIES Post hole digger Time keeping device Water/Hose RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

28 Percolation Test STEP 1: Dig a 12 min depth hole In an area designated for a stormwater BMP, dig a 12 min 24 max depth with a standard post hole digger. STEP 2: Water Note the time and completely fill the hole with water. Figure 1: Post hole digger Figure 2: 12 deep hole STEP 3: Measuring After the hole is completely filled with water note the water level at a given time increment, 10 to 15 minutes. If the water seeps slowly you may want to increase the time increment to 30 minutes. Figure 3: Fill hole with water Figure 5: Completed perc test, 30 minutes after start Figure 4: 15 minutes of infiltration STEP 4: Calculation Follow step 3 until the water has completely infiltrated into the surrounding soil, or up to 4 hours. If the water has not seeped out in 4 hours, you have poorly drained soil and may want to contact a professional, relocate the Stormwater BMP to an area with better drainage, or modify the selected BMP to a Stormwater wetland.

29 Berm and Swale Complex THINGS TO CONSIDER Do not design within 10 feet of foundation Do not back water up against buildings or foundations Berms can double as paths and trails Berms and swales are great places for vegetation Swale/Basin can occur around existing vegetation if you excavate around the tree or shrub carefully Be creative Review variations on the berm and swale complex prior to designing Berm and swale systems are utilized in the landscape to capture, direct and infiltrate rainwater into the soil specifically where it is needed. This complex allows a homeowner to develop a natural watering system focusing on maintaining vegetation needs. There are numerous variations on the basic berm and swale design. The variations are explained in the Enhanced Swale and Check Dam chapters. Reviewing BMPs in series is also beneficial. As the series becomes more complex, specifically when working in areas with steep slopes, you may want to consult one of the designers listed in Appendix C. The following pages will assist you in designing, sizing and constructing a berm and swale complex. Berm and Swale Complex Designed by Zev Friedman of Living Systems Design. For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

30 Design Berm and swales work in two parts. The swale is a swale or depression, excavated running parallel to the slope, with little to no horizontal slope. The berm is located down slope and parallel to the slope. The berm is mounded soil either from the excavated swale or additional earth, or the berm can be made of brush and rock. The basin catches water and allow water to seep into the berm. The basin and berm can both be planted and mulched. Advantages: Used on slopes from 50:1 to 4:1 (2%-25%) Berms and swales can be designed to work with existing landscape Easy to construct Minimal maintenance Disadvantages: Only work on slopes Swales with gradients greater than 10% may need additional components and structure. See Section on Check Dams and Consult the Experts Design for correct water quality storage Design errors typically lead to concentrated flow, gullies, and berm breaching Design Considerations: Utilized on slopes from 50:1-4:1. Make berms bigger rather than smaller to reduce the risk of the berm failing during a large storm event. (water breaching the berm, creating a gully). Berms have 3:1 slopes. Berms can double as paths and trails, make sure to flatten the trail portion of the berm and maintain the 3:1 side slopes. Leave a 1-foot wide undisturbed area between each berm and swale series. Can bring in soil to create berms if mature landscape is established.

31 Implementation Designing: MATERIALS Site Analysis Site Map Site Plan Schematic Calculator A-frame Level Flagging or Marking materials Hand Tamper Shovel Hard Rake Mattock Mulch Plants Vegetation Stone (optional, size varies by site) 1. Begin by reviewing your overall site analysis based on the design considerations, advantages and disadvantages to determine locations for berms and basins. 2. Once your location is determined, use the runoff volume calculation to determine the water storage capacity needed for a 1-inch storm minimum. Base the size and spacing on your site goals as well. See next page to determine swale size. 3. Use an A-frame level to layout the centerline of the berm and basin with flags or other means of marking. 4. Lay out all berms and basins, then determine if there is opportunity to connect them or if they are independent of each other. 5. Start at the top and dig basin just up slope of basin, using the excavated soil to build the berm below. You can leave established shrubs and trees within the basin; simply dig around them. 6. Bring in additional soil to create the necessary berm size if needed. 7. Level and tamp the berm under human weight and power only. 8. Locate appropriate spillways for the overflow, zig-zag to spread and infiltrate the runoff, minimizing concentrated flows. Always design the spillway flow path. 9. Revegetate or mulch any exposed soil as soon as possible after construction. Maintenance: 1. Check berms OFTEN for stability and possible areas of breaching, specifically after large storms. 2. Keep free of weeds. 3. Maintain mulch base (3 suggested) 4. Maintain level slope of swales to minimize the possibility of erosive runoff velocities.

32 Sizing Berms & Swales Helpful Conversions feet = 1 inch 0.01 meter = 1 cm 1 cubic foot = 7.48 gallons 1 cubic meter = gallons Calculating Stormwater (Runoff) Volume Runoff is precipitation that flows over the land surface and is not absorbed into the ground. In urban areas runoff is high because impermeable surfaces like rooftops, paved roads and parking lots abound. This runoff moves quickly off site through stormwater drains that usually funnel directly to streams. This helps to eliminate standing water that can cause poor health conditions and roads stay clear during storms but it does not allow water to infiltrate into the water table. In other words, the water doesn t hang around long enough to water your vegetable garden. You can change that by implementing any of the many stormwater management techniques described in this guide, but how much water can you expect to harvest? In a given storm event the amount of runoff depends on many factors, making precise calculations complicated, but a rough estimate is easily obtained by using runoff coefficients. In this method, runoff is calculated by multiplying the surface area by a coefficient (Table 1) that estimates the conditions of the particular conditions. This is then multiplied by the depth of rainfall to obtain a volume of runoff. To make the calculation easier you can assume that rainfall depth comes in units of 1 (1in or 1cm etc.), that way you ll know, for instance, how much runoff you ll have per inch of rainfall. Table 1: Runoff Coeficients Soil Groups A and B are sandier and Soil Groups C and D are more clayey. These soil classifications would be found in a county soil survey available at any Soil and Water Conservation District office or North Carolina Cooperative Extension center. Land Use/Cover 100% impervious (parking lots, rooftops, paved sidewalks or patios) Open space with grass cover <50% Open space with grass cover 50% to 75% Open space with grass cover >75% Woods in fair hydrologic condition Soil Group A Soil Group B Soil Group C (Table adapted from USDA-NRCS Curve Numbers, 1986) Soil Group D Residential lot (1/4 acre) Residential lot (1/2 acre) Residential lot (1 acre) Here s the equation: Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Here s an example of how it works: Step 1: Assess Site Conditions In this example we will use a 200 ft 2 patio Step 2: Obtain Runoff Coefficient Using the provided table (Table 1), look up the runoff coefficient that most closely resembles your site. In this case it is Step 3: Do the Math Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Volume Runoff = 200ft 2 x 0.98 x 0.083ft = 16.3ft 3 Note: Make sure that Surface Area and Rainfall Depth are in the same units. It doesn t matter what you use, just stay consistent -- measurements in feet or meters are generally easiest. Step 4: Convert if Necessary Most people have trouble thinking about water volume in cubic feet so we will convert to gallons multiplying by 7.48gal/ft 3. Volume Runoff = 16.3ft 3 x 7.48 gal/ft 3 = gallons SO In this example, for every inch of rain you will need a berm or swale that can handle 122 gallons of water.

33 Sizing Berms & Swales Calculating Swale Storage Volume Estimates amount of stormwater runoff the swales can hold given the depth, width and length of your berm and swale. 1. Water Holding Capacity Volume of H2O Capacity = Area x Length Area = 1/2 Width x Berm Height Volume = (1/2 Width x Berm Height) x Length Example: Width = 10 ft, Length = 25 ft., and Depth of berm and swale is 2 ft. Volume = 1/2 x 10 ft. x 2 ft. x 25 ft. Volume = 250 cu. ft. 2. Water capacity per foot of length Capacity= (1/2 Width x Berm Height) x 1 ft. Example: Width = 10 ft, Length = 25 ft., and Depth of berm and swale is 2 ft. Volume = 1/2 x 10 ft. x 2 ft. x 1ft. Volume = 10cu. ft. 3. Spacing Distance Distance = Capacity (per ft.)/ (Runoff Coefficient x rainfall depth) Example: Width = 10 ft, Length = 25 ft., and depth of berm and swale is 2 ft. Capacity per foot = 10 cu. ft. Runoff Coefficient (See Table 1) = 0.79 See Chapter One for Soils Information Rain fall depth= 1 inch = 1/12 = ft. Distance = 10 cu. ft. / (0.79 x 0.083) Distance = 1 ft. Spacing

34 Check Dams Check dams are low barriers within a drainage ditch, enhanced swale, or berm and swale complex. These dams sit perpendicular to the flow of water, with the intention of backing water up, to allow for infiltration and sediment removal. Check dams retain some porosity allowing for water to leak through the stones and vegetation. THINGS TO CONSIDER Slope of property and stormwater features Do not design with in 10 feet of foundation Do not back water up against buildings or foundations Be creative Typically check dams are constructed of rock with mixed vegetation to enhance stabilization and filtration. Check dams are designed primarily to provide erosion control, sediment control and remove suspended solids from runoff. Secondarily, they can provide a small amount of pollution removal. For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

35 Check Dam Design Check Dams are used to attenuate flow within a area of concentrated flow, such as an enhanced swale or a berm and swale complex. Often in this area, we have land that slopes steeply enough to create erosive velocities in concentrated flow, like in our swales. Check Dams can be used to extend the use of swales to areas with greater than a 4% slope, but should not be used without professional consulting in areas with slopes greater than 8%. Advantages: Extends use of swales past 4% slope. Relatively inexpensive and easy to construct Reduces sedimentation Can be more easily used higher in the watershed Disadvantages: Maximum slope of swale with a check dam is 8% without professional assistance. Moderate maintenance needed Can be breeched when flow volumes and/ or velocities are high during certain storm events Design Considerations: Using an erosion control blanket will help stabilize a new check dam. This material will eventually biodegrade. Using in a swale with a slope greater than 6%, you will need to flatten the slope above the check dam to provide enough ponding space during rain events. Rocks are the typical material for permanent check dams, although there is a multitude of materials such as corb fiber logs available from companies specializing in erosion and sediment control management. A mixture of rock sizes is preferable. Size of rock will depend on the slope of the drainage and drainage area. Locate in generally straight areas of the drainage, and space as suggested above based on slope of drainage and modify based on height of check dam. Check dams should occur within the limits of the drainage, but can be used as secondary crossings if necessary, although additional drainage might be needed. Planting around the edges assists in the long term stabilization.

36 Check Dam Implementation Designing: MATERIALS Site Analysis Site Map Site Plan Schematic Calculator A-frame Level Flagging or Marking materials Stone Wheelbarrow Shovel Hard Rake Mattock Plants Vegetation Filter fabric (optional) Corb fiber matting (optional) 1. Begin by reviewing your overall site analysis to determine, based on the design considerations, advantages and disadvantages to locations of the check dams. 2. Determine spacing and sizing on the slope of the drainage and height of the check dam. Slope of Spacing ft. Drainage % In selecting stones for the check dam, the size of the stones will need to increase as the volume of water and slope increase and soils 8 25 stability decreases. The largest stones should be used as the base rocks. 4. Excavate a trench into the banks and bed of the swale in order to anchor the base rocks. The trench should be dug both in the bed of the drainage and in the stabilized side slopes of the swale. Optional: Place geotextilefabric in the trench to help stabilized the check dam against large storm events. 5. Place heavier stones in the base and on the downstream side of the check dam. 6. Secure the base stones firmly in position.

37 Check Dam Implementation Designing: Regulations: Check dams can only be placed in drainage ditches, swales or berms and swale complexes. Any drainage starting above your property could be a stream managed by the Army Corps of Engineers (ACOE). Construction within the stream requires a permit for the ACOE. These streams are typically shown as blue lines on the USGS map, yet this varies in different states and municipalities. 7. Place smaller stones around the larger stones as there weight and placement help these be stable and secure as possible. The slope of the upstream and downstream faces of the check dam are determined by the angle repose. This is the ability for the stones to stay securely in place base on their, size, shape and weight. The upstream face should be more gradual (approximately 66% or 1.5-2:1) than the downstream face. 8. The top of the check dam should be concave, as the height should be no more than 1/2-1/3 of the swale depth. Maintenance: 1. Keep free of weeds 2. Inspect for damage after storm events, specifically moderate to large storm events 3. Remove sediment collected with in the pools on the upstream side of the check dam, as needed. 4. Add or remove rock as needed to maintain stability. 5. Maintain plantings

38 Enhanced Swales THINGS TO CONSIDER Do not design with in 10 feet of foundation Do not back water up against buildings or foundations Be creative Swales are slight depressions, usually trapezoidal in shape which are used to convey runoff from surrounding impervious areas. They can either run along the contour of the land or perpendicular, as long as the longitudinal slope does not exceed 5%. In the past these runoff transporting mechanisms have simply been grassed, with a turf grass. Today we can design these features with various vegetation and interest, including mimicking a dry streambed. All swales fall into two typical design groups, the dry swale and the wet swale. The following pages will assist you in designing, sizing and constructing enhanced swales. For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

39 Dry Swale Design A dry swale, also known as a grassed, vegetated or enhanced swale, is an open vegetated channel used to both treat the water quality and volume of and excess stormwater to the selected destination. An under-drain system is installed under an engineered soil mix placed under the base of the swale, similar to that of a bio-retention or rain garden in Western North Carolina to improve and promote infiltration and water quality. Advantages: Swales can be designed to work with existing landscape and in small areas Minimal maintenance Works in small drainage areas Discourages long standing water Traps sediment and other pollutants Controls peak discharge, promoting infiltration Disadvantages: Maximum slope of swale is 4% Drainage area is not to exceed 3 acres Impractical for flat or steep areas May erode when flow volumes and/ or velocities are high during certain storm events Design Considerations: Channel Shape: Trapezoidal or parabolic Bottom width: 2 ft. min. 6 ft. max. Side Slope: 3:1 or flatter, so 1 foot of rise every 3 feet Channel Longitudinal Slope: 1% min. 6% max. if over 3% slope check dams will need to be installed to reduce erosion within the channel Bottom of swale should be 3 feet above groundwater levels Do not place within 10 feet of a structure Ponding in the swale can be up to 18 depth maximum

40 Dry Swale Implementation Designing: MATERIALS Site Analysis Site Map Site Plan Schematic Calculator A-frame Level Flagging or Marking materials Gravel 6 Perforated Pipe Permeable soil mix Filter Fabric Shovel Hard Rake Mattock Mulch Plants Vegetation 1. Begin by reviewing your overall site analysis, and based on advantages and disadvantages of various designs, determine locations of swales. 2. Once your location is determined, use the runoff volume calculation to determine the water storage capacity needed for a 1 inch storm minimum. Base the size and spacing on your site goals as well. See next page to determine swale size. 3. Lay out the centerline of the swale with flags or other means of marking, using the slope tools to check slope of swale. 4. Bring in additional soil to create the necessary berm size if needed. 5. Remove all existing vegetation. 6. Dig swale maintaining a parabolic base and max. 3:1 side slopes 7. Excavate 36, lay 6 perforated pipe in bottom of excavation, along the centerline sloping down hill. 8. Surround pipe with 6 of gravel (#57). 9. Cover gravel with filter fabric. 10. Fill 30 excavation with permeabale soil mix. Maintenance: 1. Keep free of weeds 2. Inspect for signs of scouring 3. Maintain plantings

41 Wet Swale Design Wet swales are similar to dry swales in shape and purpose. The major difference is that a wet swale does not have an underdrain and permeable soil mixture under the swale base. Wet swales will have a tendency to retain water for longer periods of time than dry swales, specifically in Western North Carolina with our high clay content in the soil. Advantages: Swales can be designed to work with existing landscape and in small areas Easy to construct Minimal maintenance Works in small drainage areas Traps sediment and other pollutants Controls peak discharge, promoting infiltration Disadvantages: Maximum slope of swale is 4% Drainage area is not to exceed 3 acres Impractical for flat or steep areas May erode when flow volumes and/ or velocities are high during certain storm events Design Considerations: Channel Shape: Trapezoidal or parabolic Bottom width: 2 ft. min. 6 ft. max. Side Slope: 3:1 or flatter, so 1 foot of rise every 3 feet Channel Longitudinal Slope: 1% min. 6% max. if over 3% slope check dams will need to be installed to reduce erosion within the channel Bottom of swale should be 3 feet above groundwater levels Do not place within 10 feet of a structure Ponding in the swale can be up to 18 depth maximum

42 Wet Swale Implementation Designing: MATERIALS Site Analysis Site Map Site Plan Schematic Calculator A-frame Level Flagging or Marking materials Shovel Hard Rake Mattock Mulch Plants Vegetation 1. Begin by reviewing your overall site analysis. Look at your design options and compare advantages and disadvantages to determine locations of swales. 2. Once your location is determined, use the runoff volume calculation to determine the water storage capacity needed for a 1 inch storm minimum. Base the size and spacing on your site goals as well. See next page to determine swale size. 3. Lay out the centerline of the swale with flags or other means of marking, using the slope tools to check slope of swale. 4. Bring in additional soil to create the necessary berm size if needed. 5. Remove all existing vegetation. 6. Dig swale, maintaining a parabolic base and max. 3:1 side slopes 7. Replant with selected plants. 8. In addition to plants these swales can be formed into Dry Stream Beds and/or you can add rocks for interest and check dams to slow runoff velocities if needed. Maintenance: 1. Keep free of weeds 2. Inspect for signs of scouring 3. Maintain plantings

43 Sizing Swales Helpful Conversions feet = 1 inch 0.01 meter = 1 cm 1 cubic foot = 7.48 gallons 1 cubic meter = gallons Calculating Stormwater (Runoff) Volume Runoff is precipitation that flows over the land surface and is not absorbed into the ground. In urban areas runoff is high because impermeable surfaces like rooftops, paved roads and parking lots abound. This runoff moves quickly off site through stormwater drains that usually funnel directly to streams. This helps to eliminate standing water that can cause poor health conditions and keeps roads clear during storms but it does not allow water to infiltrate into the water table. In other words, the water doesn t hang around long enough to water your vegetable garden. You can change that by implementing any of the many stormwater management techniques described in this guide, but how much water can you expect to harvest? In a given storm event the amount of runoff depends on many factors making precise calculations complicated but a rough estimate is easily obtained by using runoff coefficients. In this method, runoff is calculated by multiplying the surface area by a coefficient (Table 1) that estimates the conditions of the particular conditions. This is then multiplied by the depth of rainfall to obtain a volume of runoff. To make the calculation easier you can assume that rainfall depth comes in units of 1 (1in or 1cm, etc.), that way you ll know, for instance, how much runoff you ll have per inch of rainfall. Table 1: Runoff Coefficients Soil Groups A and B are sandier and Soil Groups C and D are more clayey. These soil classifications would be found in a county soil survey available at any Soil and Water Conservation District office or North Carolina Cooperative Extension center. Land Use/Cover 100% impervious (parking lots, rooftops, paved sidewalks or patios) Open space with grass cover <50% Open space with grass cover 50% to 75% Open space with grass cover >75% Woods in fair hydrologic condition Soil Group A Soil Group B Soil Group C (Table adapted from USDA-NRCS Curve Numbers, 1986) Soil Group D Residential lot (1/4 acre) Residential lot (1/2 acre) Residential lot (1 acre) Here s the equation: Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Here s an example of how it works: Step 1: Assess Site Conditions In this example we will use a 600 ft 2 sidewalk Step 2: Obtain Runoff Coefficient Using the provided table (Table 1), look up the runoff coefficient that most closely resembles your site. In this case it is Step 3: Do the Math Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Volume Runoff = 600ft 2 x 0.98 x 0.083ft = 48.8t 3 Note: Make sure that Surface Area and Rainfall Depth are in the same units. It doesn t matter what you use just stay consistent measurements in feet or meters are generally easiest. Step 4: Convert if Necessary Most people have trouble thinking about water volume in cubic feet so we will convert to gallons multiplying by 7.48gal/ft 3. Volume Runoff = 48.8ft 3 x 7.48 gal/ft 3 = 365 gallons SO In this example, for every inch of rain you will need an enhanced swale that can handle 365 gallons of water.

44 Sizing Swales Calculating Swale Storage Volume Estimates amount of stormwater runoff that swales can hold given the depth, width and length of your berm and swale. 1. Water Holding Capacity Volume of H2O Capacity = Area x Length Area = 1/2 Width x Depth Volume= (1/2 Width x Depth) x Length Example: Width = 10 ft, Length = 25 ft., and Depth of berm and swale is 2 ft. Volume = 1/2 x 10 ft. x 2 ft. x 25 ft. Volume = 250 cu. ft. 2. Water capacity per foot of length Capacity= (1/2 Width x Depth) x 1 ft. Example: Width = 10 ft, Length = 25 ft., and Depth of berm and swale is 2 ft. Volume = 1/2 x 10 ft. x 2 ft. x 1ft. Volume = 10cu. ft. 3. Spacing Distance Distance = Capacity (per ft.)/ (Runoff Coefficient x rainfall depth) Example: Width = 10 ft, Length = 25 ft., and depth of berm and swale is 2 ft. Capacity per foot = 10 cu. ft. Runoff Coefficient (See Table 1) = 0.79 See Chapter One for Soils Information Rain fall depth= 1 inch = 1/12 = ft. Distance = 10 cu. ft. / (0.79 x 0.083) Distance = 1 ft. Spacing

45 French Drains THINGS TO CONSIDER French Drains are simple subsurface drainage trenches which collect and move sub-surface drainage to a desired location. These drains are an option for removing excessive wetness in unwanted areas. These drains are commonly used in this area to reduce water from around the foundation of a building and its basement (if applicable). In simplicity, a French drain is a trench filled with gravel and a perforated pipe at the bottom. Utility Lines Slope of property Source of drainage issue (wetness) For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

46 French Drain Design Designing: In designing your French drain there are a few things to take into consideration. This includes the shape of the property surrounding the wet foundation/basement or depression. If the property slopes down towards the foundation, sending water downhill and into the foundation, you will benefit from reshaping this area to drain away from the foundation. Remember water runs downhill. MATERIALS: Advantages: Disadvantages: Shovel Mattock 6 or 4 Perforated pipe, length will vary Standard gravel (#57 stone) Filter fabric pipe sock or wrap Landscaping cover Stones for outfall (optional) Removes moisture from unwanted locations Sub-surface (unseen) Can clog or fail overtime, unnoticeably Slope of drainage Typically linear Design Considerations: The location of the excessive moisture and the location the pipe daylights. At this point the water is concentrated and needs to be dispersed appropriately. Linking the French drain to a stormwater feature can mitigate the concentrated flow.. The shape of the land around the area of excessive moisture. Is the property sloping towards the foundation of a building? Is there a natural depression? Slope of the land Drains located adjacent to the foundation should be placed at a minimum 2 out from the foundation.

47 French Drain Implementation Designing: 1. Locate your French Drain: Your site analysis will help in locating the French drain. Make sure to locate all utility lines so you can route your drain to avoid these elements if possible. If a utility line must be crossed contact the service provider for assistance in placing the perforated pipe below the utility and add a pvc or other buffering sheath to protect the utility line. In some cases, like with gas lines, the utility company will need to by hired to do this. Avoiding them is the best option. If your basement or foundation is wet after rain events, then a French drain would be necessary along the foundation where the moisture is apparent. These locations are usually higher in elevation than the basement floor or foundation. It would be useful to extend the drain past current areas of wetness to cover any additional drainage during larger storm events. Drains located adjacent to the foundation should be placed approximately 2 out from the foundation. Locate the place you would like the 6 perforated pipe to daylight, preferably into a stormwater BMP. Route the drain from the location of excessive moisture to the daylight point. The daylight point must be lower in elevation than the drain itself. The pipe should slope down consistently at a slope between 2% to 10%. The steeper the slope the higher velocity of the water coming from the drain pipe, therefore the outfall my need additional armoring with stones. 2. Excavate a trench 6 to 8 inches wide and a minimum of 18 in depth, along the routing line, sloping the trench consistently to the outfall location. 3. Place 2 of gravel in the trench. 4. Wrap 4 or 6 perforated pipe with filter fabric (optional). The filter fabric will minimize clogging of individual perforations in the pipe. 5. Lay pipe in the trench and back fill with gravel up to 2-3 below ground surface. 6. Cover with soil and either seed with grass or mulch over the drain.

48 Rain Barrels HOW MUCH WATER WILL YOUR RAIN BARREL COLLECT? For every 1000 square feet of collection area, you can expect to collect 600 gallons of water for every inch of rain. The roof on an average home has about 1200 square feet of collection area. In Asheville, where the annual rainfall is about 47 inches, one could potentially collect 33,840 gallons of rainwater per year! Rain barrels are a great way to conserve water, are relatively inexpensive and easy to install. These easy to follow, illustrated instructions give you all you need to construct a rain barrel of your own. Either do it yourself or join us for one of our rain barrel workshops. Workshop details can be found by visiting us on the web at or by signing up for our newsletter (information@riverlink.org). RiverLink also sells predrilled barrels for $15 and if you don t have the time to build your own, you can buy a completed barrel for $60. RiverLink Rain Barrel Built at April 2011 Workshop For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

49 Overview Rain barrels are water storage units designed to collect water from impermeable surfaces like your roof. The most common type of rain barrel collects runoff from your roof by connecting to your gutter downspouts. The catchment is usually a 55 gallon barrel fitted with a spigot. The system is gravity fed so no pumps are necessary. This simple and effective design is what you will build following these easy four-step instructions. MATERIALS For Barrel 55 gal. drum, plastic 3/4 spigot Fine mesh screen Downspout adaptor sized to fit your gutter downspout Corrugated plastic pipe, elbow sized to fit downspout adapter PVC drill bit sized to fit corrugated plastic pipe Silicone caulking Pipe tape Power drill 1 1/8, 1 7/8 drill bits Metal cutters Cinder blocks To the right you will find a list of materials needed to complete your rain barrel. You ll begin the project by preparing the barrel. Next you ll install the overflow and then the spigot. Lastly, you ll attach the barrel to the downspout and you ll be ready to begin water collection. At the conclusion of these instructions you will also find maintenance tips to help you care for your new rain barrel. Let s begin! For Overflow Spout (Choose Rigid or Flexible option) Rigid PVC primer PVC cement 1.5 PVC adapter 1.5 PVC elbow Flexible 1.5 nylon adapter 2 or 2.5 flexible tubing

50 Step One: Prepare the Barrel 1. Thoroughly rinse the barrel to remove any potential contaminants. 2. Using the power drill and the PVC drill bit, drill a hole through the middle of the top of the barrel. MATERIALS For Barrel Plastic 55 gallon drum Power drill PVC drill bit sized to fit your gutter adapter (usually between 4 1/2 and 6 ) 1 7/8 drill bit 1 1/8 drill bit Cut-to-fit screen Silicone caulking 3. Next, drill a 1 7/8 hole in the left side of the barrel one inch from the top. Then, drill a 1 1/8 hole at the base of the front of the barrel for the spigot. 4. Remove any plastic shavings that may have fallen into the barrel. 5. Cut the screen to overlap the hole by about an inch and glue down tightly using silicone caulking or other appropriate glue. Allow glue to dry before first rain event.

51 Step Two: Install the Overflow MATERIALS Before installing the overflow you need to choose whether you would like a flexible drain spout that you can use to direct overflow away from the barrel (Option 1 below) or a rigid spout (Option 2 on the next page) that drains overflow at the barrel. Flexible Overflow 1 1/2 nylon adapter 2 flexible tubing (length of your choosing) PVC primer PVC cement Pipe tape Silicone caulking Adjustable #16 clamp or zip-tie Overflow Option 1: Flexible Spout 1. Tightly wrap the threaded end of the 1 1/2 nylon adapter with pipe tape and screw into 1 7/8 hole at the top left hand side of the barrel. Seal the joint with silicone caulking. 2. Firmly push the flexible tubing onto the adapter to attach. Slide the adjustable clamp or zip-tie into place and tighten.

52 Step Two: Install the Overflow Overflow Option 2: Rigid Spout 1. Prime the inside of the female (unthreaded) end of the 1 1/2 adapter and the outside of the male (thinner) end of the elbow with the PVC primer. MATERIALS Rigid Overflow 1 1/2 PVC adapter 1 1/2 PVC elbow PVC primer PVC cement Pipe tape Silicone caulking 2. Glue the adapter and elbow together using PVC cement to create overflow spout. 3. Tightly wrap the threaded end of the adapter with pipe tape and screw overflow spout into 1 7/8 hole at the top left-hand side of the barrel. Point the spout downwards (and away from your foundation) and seal the joint with silicone caulking.

53 Step Three: Install the Spigot MATERIALS 1. Tightly wrap the threaded end of the spigot with pipe tape and screw into 1 1/8 hole at the bottom front of the barrel. Spigot 3/4 spigot Pipe tape Silicone caulking 2. Point the spout downwards and seal the joint with silicone caulking.

54 Step Four: Install Rain Barrel Choosing Your Location The rain barrel should be below the gutter downspout of your building and elevated off the ground enough to easily access the spigot. Note that the higher the barrel is off the ground, the greater your water pressure will be. MATERIALS Installation Downspout adaptor sized to fit your gutter downspout Corrugated plastic pipe, elbow sized to fit downspout adapter Cinder blocks Metal cutters 1. Clear your gutter of debris to avoid clogging your new rain barrel. 2. Elevate the barrel on the cinder blocks. Using the metal cutters, cut the gutter downspout 1-2 ft. above the top of the barrel. Make sure barrel is level so it won t slip off its foundation when it is full. 3. Fit the downspout adapter securely onto the gutter downspout. 4. Insert the corrugated pipe into the hole at the top of the barrel. 5. Fit the downspout adapter securely together with the corrugated pipe. Your rain barrel is ready to start collection!

55 Caring For Your Rain Barrel With the proper care rain barrels can last many years. Here are some tips to keep your rain barrel functioning properly. General Maintenance RAIN BARREL CHECKLIST DO Clear your gutters Periodically clean barrel and piping Check for leaks Keep screen securely attached Drain each winter DO NOT Drink or water your pets from your rain barrel Allow young children to climb on your rain barrel Keep your gutters clean to ensure unobstructed flow to your rain barrel. Mosquitoes are generally not a concern as long as your screen is secure, but as a precautionary measure use the water from your barrel often as mosquitoes favor stagnant water. Use of your water once every three days should be sufficient. Scrub your barrel periodically to remove particulate buildup. Inspect your rain barrel often for leaks, cracking and clogging. Repair as needed. Drain the rain barrel during winter if freezing is a concern (see winterizing below). Winterizing Your Rain Barrel In winter, when freezing temperatures are a concern, you will need to discontinue use of your rain barrel to avoid cracking the barrel. Drain and clean, then plug the barrel or store upside down to keep dry. This is also a good time to unscrew and clean your spigot. Taking your rain barrel offline will require you to add additional piping to your gutter downspout to direct water away from your building.

56 Rain Gardens Rain gardens are small vegetated depressions used to promote infiltration of rainfall runoff from roofs, driveways, and sidewalks. Rain gardens combine grasses, shrubs, and perennials with mulch and soil to filter pollutants in the water runoff. Vegetation is critical to the proper function of a rain garden and proper plant selection is important. The following pages will assist you in designing, sizing and constructing a rain garden. THINGS TO CONSIDER ABOUT YOUR RAIN GARDEN Do not design within 10 feet of foundation Do not back water up against buildings or foundations Rain Gardens are an amenity Make sure to do a percolation test to determine the permeability of your location Be creative Evergreen Charter School For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

57 Design Rain gardens are best suited for well-drained sandy soils, but can be installed in areas with less permeable soils, such as clay. In Western North Carolina you can design the rain garden more as a constructed wetland, or as this guide suggests, by excavating soil material and replacing it with a more permeable soil mix. Rain gardens in impermeable soils shall be designed as a constructed wetland. Advantages: Can be integrated into existing site easily Can be large or small, dependent on drainage area (max drainage area is 1 acre) Provide an aesthetically pleasing amenity Used at sites where storm sewers are not available Can provide groundwater recharge Disadvantages: Evergreen Charter School Ponding water may take 24 to 48 hours to drain Some maintenance, plant maintenance and keeping the basin clean, clean out overflow Should not be used for lots with high sediment loading, especially clay deposits Design Considerations: Depression can be 6 to 18 inches in depth. Pre-treat runoff through overland sheet flow, for at least 4 feet at no more than 10% slope (i.e. 4 grass strip). Locate your Rain Garden in natural depressions or appropriately for water to drain into the depression through overland or gravitational flow. Rain Garden should not be within 10 feet of a building foundation. Locate at least 25 feet from septic tank or well head. Locate where the water table is at least 3 feet below the surface at the lowest point in the depression.

58 Sizing Rain Gardens Sizing your Rain Garden: The size of the rain garden is dependent on the area of impervious surface and the volume of water. In NC we try to capture runoff from the first inch of rain fall. To determine the size of your rain garden you need to determine to sources of runoff and the square footage of impervious surface. Helpful Conversions feet = 1 inch 0.01 meter = 1 cm 1 cubic foot = 7.48 gallons 1 cubic meter = gallons If you take the total impervious area draining into the garden and divide that area by 20 you will get a rough estimate of the garden s area, at a depth of 6 inches. NCSU has developed a sizing chart for 6 and 3 depths. Example: 5000 square foot impervious surface 5000/20 = 250 sq. ft. at 6 depth The State of Maryland, where original rain garden designs emerged, suggests the rain garden be 5 to 7% of the impervious area draining into the garden. Example: 5000 square foot impervious surface 5000x.05= 250 sq. ft or 5000x.07= 350 sq. ft. Calculate Runoff Volume Yourself: Another easy way to calculate runoff is by multiplying the surface area by a coefficient (Table 1 on next page) that estimates the conditions of the particular conditions. This is then multiplied by the depth of rainfall to obtain a volume of runoff. To make the calculation easier you can assume that rainfall depth comes in units of 1 (1in or 1cm etc.), that way you ll know, for instance, how much runoff you ll have per inch of rainfall. Here s the equation: Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Here s an example of how it works: Step 1: Assess Site Conditions In this example we will use a 2500 ft 2 lawn in poor condition that is covered only with approximately 45% grass Step 2: Obtain Runoff Coefficient Using the provided table (Table 1), look up the runoff coefficient that most closely resembles your site. In this case it is Step 3: Do the Math Volume Runoff = Surface Area x Runoff Coefficient x Rainfall Depth Volume Runoff = 550ft 2 x 0.68 x 0.083ft = 31ft 3 Note: Make sure that Surface Area and Rainfall Depth are in the same units. It doesn t matter what you use just stay consistent measurements in feet or meters are generally easiest. Step 4: Convert if Necessary Most people have trouble thinking about water volume in cubic feet so we will convert to gallons multiplying by 7.48gal/ft 3. Volume Runoff = 31ft 3 x 7.48 gal/ft 3 = gallons SO In this example, for every inch of rain you can expect to harvest about 232 gallons of water.

59 Sizing Rain Gardens Runoff Coefficients Table 1: Runoff Coefficients Soil Groups A and B are sandier and Soil Groups C and D are more clayey. These soil classifications would be found in a county soil survey available at any Soil and Water Conservation District office or North Carolina Cooperative Extension center. Land Use/Cover 100% impervious (parking lots, rooftops, paved sidewalks or patios) Soil Group A Very Sandy Soil Group B Sandy Soil Group C Clayey Soil Group D Very Clayey Open space with grass cover <50% Open space with grass cover 50% to 75% Open space with grass cover >75% Woods in fair hydrologic condition Residential lot (1/4 acre) Residential lot (1/2 acre) Residential lot (1 acre) (Table adapted from USDA-NRCS Curve Numbers, 1986)

60 Implementation Designing: MATERIALS Site Analysis Site Map Site Plan Schematic Calculator Flagging or Marking materials Spade Shovel Hard Rake Mattock Mulch Plants Vegetation OPTIONAL Sand/Gravel or Compost (optional) size varies by site 1. Begin by reviewing your overall site analysis to determine, based on the design considerations, the advantages and disadvantages of various rain garden placements to determine the best location. 2. Once your location is determined, use the runoff volume calculation to determine the water storage capacity needed for a 1 inch of rain (minimum). Base the size and spacing on your site goals as well. See next page to determine rain garden size. 3. Conduct a percolation test (Chapter One) to determine if the location is suitable for infiltration. 4. Once location and size are determined, lay out rain garden with marking flags or paint. 5. Begin digging out garden, approximately 4-8 deep with a depression in central ponding area. 6. Construct a berm (see Berm and Swale Complexes) with a 6 rise on the downhill edge of the garden. 7. Optional: Adding compost to the top layer of well drained soils will assist in infiltration and plant growth. For clayey or compacted soils, mix sand or gravel to improve infiltration. 8. Plant. See Appendix A for list of native rain garden plants for the Southern Appalachians. 9. Mulch with 2-3 inches of hardwood mulch. Maintenance: 1. Check berm for stability and possible areas of breaching, specifically after large storms. 2. Keep free of weeds and fine sediment. 3. Maintain mulch base (3 suggested)

61 Additional Resources North Carolina Cooperative Extension: Backyard Rain Gardens: Low Impact Development Center: whatisaraingarden.htm North Carolina Department of Environment and Natural Resources: NC State University: Urban Waterways Designing Rain Gardens: University

62 IN THIS CHAPTER: When to contact an expert Types of experts Bioretention Permeable Surface Stormwater wetland Consult the Experts Often given the terrain of our landscapes and our clay dominant soils, you will find the need to reach out to an expert familiar with designing stormwater management features in this area of North Carolina. What type of professional you should reach out to depends on the scale and scope of the project or issue. My site analysis identified potential red flags in the design process. Who do I call? There are numerous types and levels of professionals who can provide assistance in managing stormwater on your property. These include landscaper contractors, design-build landscapers, engineers, landscape architects, environmental engineers and geotechs. Under different circumstances you will want to contact different levels of professional. Landscape architect, engineers and geotechs, are all licensed professionals able to certify drawings. This is necessary for any situation where you need to permit the project at any level. Landscapers, landscape designers, and designbuild firms can be licensed contractors, but are not typically professionally licensed. In Appendix C we have listed a number of professionals that have experience in this work. Bio-retentions, permeable surfaces, and stormwater wetlands are excellent stormwater management tools but they can be tricky to implement. Here we ll describe the basics of these tools. If you decide you want to use one of them we recommend seeking advice from the experts, see Appendix C for a list of applicable local contractors. For more information contact: RiverLink 170 Lyman Street P.O. Box Asheville, NC Phone: Fax: information@riverlink.org

63 Bioretention Bioretention areas are vegetated depressions intended to catch and filter stormwater run-off. They are constructed with plants, an underdrain system and engineered soil to improve filtration and absorption. Design Considerations: Pretreatment area optional, filter strip or forebay Inlet and outlet controls Underdrain cleanouts and maintenance Ponding depth 6-12, usually 6 Sensitive to high sedimentation rates, which can clog the system Small drainage areas, under 3 acres Effective at removing heavy metals, nitrogen, phosphorous, and pathogens. Call a landscape architect or engineer for assistance. Figure 1: (top) Bio-retention area in the rain Figure 2: (bottom) Bioretention under construction, white pipe is the overflow device, engineered soil mix has been placed over the underdrain system Figure 3: Bio-retention design

64 Pervious pavers Pervious pavers or porous pavement are hard or reinforced surfaces which allow for infiltration through the material. There are numerous types of pervious pavers and porous paving. Porous pavement, such as porous concrete or porous asphalt, consists of a uniform material resembles its impervious counterpart. The pavements are not typically recommended for use in this area, due to the high clay content in our soil, which limits porosity and ability for water to infiltrate. Design Considerations: Soil permeability Small drainage area Sensitive to high sedimentation rates, can clog the system Reduces overall runoff volume Variety of selection Contact landscapers, design build firms, landscape designers or landscape architects for assistance. Due to the potential small scale of these paving projects, landscape architects or engineers may steer you towards a designer. Pervious pavers are suited better for this area and come in a surprising variety of materials, forms, and colors. These include: interlocking pavers, turf reinforcing, and grid pavers. NCSU is currently testing various permeable pavements and pervious pavers to determine the best construction and use practices in this area. Figure 1: Grid pavers Figure 3: Porous Asphalt and pervious pavers Figure 2: Grass plastic grid re-inforcement

65 Stormwater wetlands Figure 1: Stormwater wetland diagram Figure 2: Stormwater wetland, West Asheville Park Design Considerations: Pretreatment area optional, or forebay Inlet and outlet controls Water table location Ponding depth 6-18 Often used due to poor soil permeability Effective at removing heavy metals, nitrogen, phosphorous, and pathogens. Contact landscapers, design build firms, landscape designers, engineers or landscape architects for assistance. Due to the potential small scale of these paving projects, landscape architects or engineers may steer you towards a designer. Stormwater wetlands are constructed wetlands that are intended to trap and filter pollutants, as well as retain run-off volume. They are planted depressions which remain wet during a majority of the year. There are no drainage systems associated with the wetland, only an outfall directing water to the appropriate location if the wetlands was to fill completely. Figure 3: Stormwater wetland, Carrier Park