Planning with Surface and Ground Waters
After spending time evaluating the drainage characteristics of your property, completing the checklist and locating potential problem areas, you may feel ready to start taking action on your drainage issues. However, before you go forward you should take advantage of published information, public agency guidance, and opinions from technical experts in specific areas (see links section for more information). Seeking additional resources and guidance will allow you to clarify or modify your checklist notes on your property. You should resist jumping from your initial property observations directly to the installation of drainage control elements. If you spend just a little time with site planning, you may be able to pull the pieces of your drainage observations into a coordinated system which can help you avoid relocating problems from one area to another.
Making a plan (drawing) is the best way to organize your drainage control system and is certainly the best way to communicate your approach to others (view example drawing). Nearly everyone feels comfortable with pictures. Your drawing will help everyone associated with your property clearly know the nature and extent of your proposed work. Governmental agencies that may be involved in project permit approval usually request if not require a property drawing or plan. The drawing may be part of a more formal submittal to an agency usually called a drainage control plan. The plan may include a drawing of your property and some written descriptions of the project. Regardless of the different reasons for a plan, it is in your interest to create a drawing because of the following:
There are three primary types of information you are likely to put on your drawing: general topography, existing features, and planned features. Each of these pieces of information is fairly easy to acquire. For topography you have the choice of either hiring a professional surveyor to do a boundary and topographic survey or generating portions of the plan yourself. If the planning area is small with the topography contours and boundary lines easily established, you may decide to undertake the work yourself. To begin the drawing, you must identify the locations of your property corners and general property dimensions. You will need a pencil, a protractor, straight edge and an engineer's scale or ruler in order to sketch the configuration of your property on a large sheet of paper. Using a scale of one inch on paper equals 20 feet on your property usually works fine for most sites where the planning area is restricted to under an acre. Otherwise, you can use a scale of one inch equals 30 feet or greater.
Setting topographic contours or grades in a small open area of roughly a couple hundred feet square can be performed measuring or estimating the vertical drop per 100 feet. The feet dropped in 100 feet equals the average slope angle in percent (i.e. 2 feet in 100 feet equals 2 percent). On steep slopes, you may be able to only approximate the grade but still be sure to identify the locations of your observed features.
For most sites there are enough complex issues or enough area to cover that it helps to hire a surveyor to do a topographic site plan. The surveyor can also locate any existing features on your property that you identify. The locations of roads, houses, landscaping, outbuildings, the top and bottom of slopes, existing drainage features, and septic systems can all be included in your topographic survey work. Remember to check any survey against what you actually observe on your property. Typically, you will need to add more detail to your plan than what is shown.
Now that you have most of the information shown on your plan, the last remaining bit of information is to identify features that are part of any planned construction. With your plan showing existing site information you can now locate potential drainage improvements on your site. Review this booklet along with other references before choosing the final location any proposed drainage system improvements.
The Department of Ecology Water Quality Program as part of the Puget Sound Water Quality Management Plan suggests that both small and large parcel construction projects put together an Erosion and Sediment Control Plan. The Water Quality Program identifies small parcels as properties having: individual, detached single family residences and duplexes; created or added less than 5,000 square feet of impervious area (driveways, parking lots, roof area, etc.); and land disturbing activities of less than one acre. Your plan may satisfy all or part of any erosion and sediment control plan. Check with your local public works department for more details on specific drainage or drainage plan requirements. A typical drainage plan package submitted to your local building and planning office usually includes the following basic information: location of property and physical description of the property; a scaled plan (drawing) of the property showing accurate locations of existing and proposed structures and topography; locations of drainage system(s) and erosion control measures; limits of site disturbances; locations of any required setbacks and critical areas; and identification of the final points or areas of water discharge.
The state Hydraulics Act, designed to protect fish and their habitats, requires that an HPA (Hydraulics Project Approval) be obtained for any work that occurs in state waters. An HPA will typically be required for shoreline bulkheading, placement of drainage outfalls below the ordinary high water line, or any modification of the beach.
Coastal bluffs are sensitive ecological areas and may be identified as critical habitats or may support rare or protected wildlife species. Heron rookeries and trees used as eagle nest sites are examples of protected habitat areas. Contact your local planning office or the Department of Fish and Wildlife's Habitat Division.
The Shoreline Management Act (SMA) applies to many activities that occur within 200 feet of the shoreline. Each local government administers the SMA through its Shoreline Master Program and each jurisdiction may regulate activities differently. Contact your local planning office to see what activities require a shoreline substantial development permit and which are exempt on your particular shoreline.
Local jurisdictions may require permits or approvals for some types of drainage work. In general, individual property owners are not subject to permit requirements for stormwater control and discharge. Outfalls from subdivisions larger than 5 acres may be required to obtain an NPDES (National Pollution Discharge Elimination Standard) permit. Contact your planning and public works departments or the Ecology water quality program staff at the Permit Coordination Center for more specific information that affects your property.
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