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Thurston County, Washington

The content on the Thurston County website is currently provided in English. We are providing the “Translation” for approximately 10 languages. The goal of the translation is to provide visitors with limited English proficiency to access information on the website in other languages. The translations do not translate all types of documents, and it may not give you an exact translation all the time. The translations are made through an automated process, which may not result in accurate or precise translations, particularly of technical and legal terminology.

A site plan is a scale drawing that shows your project property and where existing and proposed development will be located on it.  Check out this site plan example (PDF).


  • Site plans can be hand-drawn or prepared using design software.
  • Make sure the plan is clear and readable.
  • The plan should be drawn to a standard engineer scale (example: 1" = 30' or 1" = 100').
  • The plan should be on an 11 X 17 sized piece of paper, or smaller sheet. 
  • The plan should be in black ink. Colored site plans or aerial photographs are not accepted.
  • All applicable items noted below shall be addressed on the site plan.
  • Use two site plans for large parcels that do not fit on an 11 X 17 sheet. One overall site plan showing the entire property and one detail of the area to be developed. See reverse side for example.


  • All property boundaries and dimensions
  • North arrow, site address, tax parcel number and map scale used size of property
  • Footprint of all existing and proposed structures (please identify structure type: house, barn, shop, shed, etc.) 
  • Existing and proposed driveway locations and easements 
  • Location of all existing and proposed utilities such as septic tanks, drainfields, drainfield reserve areas, sewer lines, water lines, wells, and springs. 


  • All known critical areas and buffers (example: wetlands, streams, steep slopes, flood plain, high groundwater) 
  • Topographic information for entire property. Contour information may be provided on a separate sheet. Information may be obtained from Thurston County Geodata Mapping based on available County 2 foot contour maps. A note shall be made on the site plan if the parcel is flat. 
  • Areas to be cleared, graded, filled, excavated or otherwise disturbed 
  • Impervious surface calculations. Use the attached impervious surface worksheet to assist you with your calculations. Submit the worksheet at the time of application or show calculations on the site plan. Additional calculations may be requested for shoreline properties. 
  • Vicinity sketch showing property location in relation to major roads and highways 


  • Storm Water Drainage Plan - The site plan shall demonstrate how storm water will be managed, learn more on the (NEW PAGE FOR DRAINAGE REQUIREMENTS PAGE). The following shall be noted on the site plan. The location and type of storm water drainage facility proposed for the project (Example: gutters with down spouts, splash blocks, drywell, infiltration trench, and other stormwater connections, etc.) 
  • Location and type of erosion/sediment control (Example: silt fence, straw wattles, etc)