DPD's Site Development Team provides site review and technical advice on geotechnical, grading and drainage components of construction projects.
You must work with one or more site development staff if your construction project requires any of the following:
For additional information on the above topics and other site development-related issues, both DPD and SPU provide a number of Client Assistance Memos (CAMs).
Pre-Application Site Visit (PASV)
If you are applying for a construction (building, demolition, or grading) permit or planning for future construction (land use permit) that involves ground disturbance (including staging areas) or tree or vegetation removal, advance inspection of your site (PASV) by DPD's Site Development Team may be required.
Previously, many applicants would submit applications lacking key documentation, technical reports, topographic surveys and/or plan information required by code or necessary to complete plan review. The PASV helps DPD staff evaluate mapped and existing conditions on a property relative to the proposed construction, which allows for efficient plan review by predetermining the materials needed for application submittal.
Field conditions to be evaluated during the PASV include, but are not limited to: steep slopes, wetlands, drainage patterns, large trees, existing structures, flood plain, street curb and abutting property line improvements that might be affected by the proposed development. Design issues include, but are not limited to: location of existing and new slopes, and structures such as retaining walls and their relation to proposed and existing construction.
Exceptions may include projects that qualify for Subject to Field Inspection (STFI) permitting and projects that involve less than 750 square feet of ground disturbance, as long as the site is not located in an Environmentally Critical Area. Typically, a PASV will not be conducted with an STFI for these projects, but rather a site inspector will perform a first ground disturbance site inspection after the permit is issued but before work begins.
Download the PASV form from DPD's Forms page.
Temporary Erosion and Sedimentation Control (TESC)
A construction stormwater control plan is required for all projects that will require ground disturbance, including grading and footing excavation, in order to prevent erosion or transport of sediment or other pollutants from the construction site. To achieve this, DPD has developed the Temporary Erosion and Sedimentation Control (TESC) plan (formerly known as the Small Project Construction Stormwater Control Plan or Construction Stormwater Control Prescriptive Plansheet), which includes a checklist and the standard best management practices (BMP). This document is available in both pdf and CAD format on DPD's Forms page.
Environmentally Critical Areas (ECA)
City of Seattle Regulations for Environmentally Critical Areas (SMC Chapter 25.09) regulate development affecting landslide-prone, liquefaction-prone and flood-prone areas, wetlands, riparian corridors, steep slopes, fish and wildlife habitat conservation areas, and abandoned landfills. Development in these areas requires preparation of a surveyed site plan and submittal of additional information relating to critical areas and their buffers as part of the application and review process. You can find more information in CAM 103B, Environmentally Critical Area Site Plan Requirements.
In some cases DPD may allow exemptions to the ECA regulations or modifications to the submittal requirements. See CAM 327A, CAM 327B and CAM 328 for more information.
Dry Season Grading Restriction - Grading for project sites containing ECAs is often restricted to the time period between April 1 and Oct. 31, with all grading required to be stabilized by Oct. 31. The grading restriction can also be applied under the authority of Section 22.804.160A of the City of Seattle Stormwater, Grading and Drainage Control Code for project sites that do not contain ECAs. If a Dry Season grading restriction has been attached to your project, you may download the Dry Season Extension Application and instructions from the DPD Forms page.
Natural Drainage Systems - Swales, ravines and stream corridors such as Thornton Creek or Longfellow Creek are all examples of natural drainage systems. Natural drainage systems cross privately and publicly owned property. Most stormwater that enters a natural drainage system is untreated.
Some natural drainage systems-related links:
Natural Drainage Projects - Direct link to Seattle Public Utilities (SPU) program
High Point Project - Direct link to the Seattle Housing Authority website
Stormwater - Stormwater is the water that originates from rainfall and other precipitation. In natural landscapes rain predominantly is caught by trees and vegetation, or infiltrates the soil. In urbanized areas rainfall hits impermeable surfaces such as rooftops and paving. Instead of infiltrating the soil or being used as hydration for vegetation it must be managed through urban infrastructure systems.
Stormwater is managed through Seattle's Stormwater Code and four associated DPD Director’s Rules. These requirements all work together to provide a comprehensive framework for managing the quality and quantity of stormwater.
Sustainability - Recognizing that water is a defining element in our local ecosystem, the City of Seattle encourages stormwater management strategies aimed at reconnecting our communities to the natural water cycle and use of alternative methods of flow and drainage control to preserve our resources. DPD's Sustainable Building Program promotes the following stormwater management methods for use during construction and throughout the life of a project:
- Controlling erosion to reduce negative impacts on water and air quality.
- Limiting disruption of natural water flows by minimizing stormwater runoff, increasing on-site infiltration and reducing contaminants.
- Limiting or eliminating the use of potable water for landscape irrigation.
- Reducing the generation of wastewater and potable water demand, while increasing local aquifer recharge.
Trees & Vegetation - If you plan to remove trees and vegetation in Seattle's Environmentally Critical Areas (ECAs) you may need a permit from DPD for the portion of the site designated as an ECA. This requirement applies when certain thresholds are exceeded, as described in CAM 331, Environmentally Critical Areas: Tree & Vegetation Removal Permits.
However, when tree and/or vegetation removal in an ECA is proposed as part of a building permit or master use permit application, DPD will conduct review and analysis as part of the building and project review. Tree or vegetation removal shown as part of an issued building, grading or master use permit does not require a separate tree or vegetation removal permit.
Specified ECAs and applicable restrictions are detailed in the Seattle Municipal Code Section 25.09.320 (direct link to the City Clerk's website), which is administered by DPD.
Temporary Shoring and Excavation
During the Pre-Application Site Visit, site development staff assess the likelihood that temporary shoring and excavation will be needed. These methods are used on construction sites to facilitate the installation of retaining structures, utilities and below grade elements of structures, notably where insufficient space exists to use temporary sloped embankments to complete the work on the subject property.
Staff evaluates proposed shoring measures and excavations during plan review for permit applications. Following permit issuance, DPD staff work collaboratively with the geotechnical special inspector (nominated by the owner and approved by DPD), the structural engineer, architect and contractor to complete the shoring and excavation phase of construction with minimal disruption to adjacent properties.
- CAM 111 - Construction and Development in Floodplains
- CAM 234 - Landscaping Information
- CAM 242 - Tree Protection Regulations in Seattle
- CAM 321 - Rockeries: Prescriptive Design and Installation Standards
- CAM 324 - Reducing Landslide and Stormwater Erosion Damage: What You Can Do
- CAM 327A - Environmentally Critical Areas Exemptions Relief from Prohibition on Steep Slope Development, and Modifications to Submittal Requirements — Application Instructions and Submittal Requirements
- CAM 327B - Environmentally Critical Areas — Small Project Waivers Application Instructions and Submittal Requirements
- CAM 328 - Environmentally Critical Areas Exceptions
- CAM 330 - Environmentally Critical Areas-Yard and Setback Variance
- CAM 331 - Environmentally Critical Areas—Tree and Vegetation Overview
- CAM 331A - Environmentally Critical Areas—Vegetation Restoration
- CAM 331B - Environmentally Critical Areas—Hazard Trees
- CAM 502 - Grading Regulations in Seattle
- CAM 503 - Side Sewer Permits in Seattle
- CAM 504 - Side Sewer Site Plan Requirements
- CAM 505 - High Point Impervious Surface Calucation
- CAM 506 - Side Sewer Permits for Temporary Dewatering on Construction Sites
- CAM 507 - Side Sewer Permits for Build-Over Agreements
- CAM 508 - Grading and Retaining Wall Construction Near or Adjacent to Property Lines
SPU Client Assistance Memos (CAMs) relating to Site Development