Strawberry Point School Field & Wetland

Mill Valley, CA

Mill Valley School District
Summer/Fall, 2007

This unique project combined the restoration of an old play field with a tidal wetland habitat restoration, all situated behind Strawberry Point Elementary School in Mill Valley, CA.  Hanford ARC contracted to complete all elements of the project.

The project involved substantial community input, and the PTA raised funds for the field restoration.  As mitigation for the field construction, the adjacent tidal wetland was expanded, and a small freshwater wetland was created within the school property.  Brian Powell and Associates, Inc. designed the project to include a community accessible path to interface the wetland and field environments.  Hanford ARC constructed the field and wetland concurrently, which simplified material handling and project management.  Furthermore, the project layout was consolidated, and we utilized our new GPS system to perform accurate layout of both the field and wetland.

The GPS system allows survey level accuracy to be achieved for any location on the site during construction staking by Hanford ARC.  The process involves hiring a surveyor to provide control points and setting up a base station to be undisturbed during construction.  Once setup, the system is used to perform all layout, volume calculation and as-built surveys.

The field area included a new freshwater, seasonal wetland designed to receive storm water runoff from the school’s paved areas and building tops.  A 640 LF berm was rebuilt as a base for a decomposed granite path and to provide flood control for the school yard.  The berm is fenced on the wetland side with gated access to the tidal marsh for biological monitoring and educational purposes for the school.

Following field excavation and soil import, we installed 280 LF of 4” perforated pipe and approximately 10 Christy boxes at the base of the berm to increase field drainage.  140 LF of 6” SDR and 200 LF of 10” SDR were installed and tied into the existing drainage system. The irrigation system installed to maintain approximately 200 new plants and 50,000 SF of sod consisted of 680 LF of mainline tied in to the schools existing system and 2,840 LF of lateral line connecting to a drip system and approximately 80 sprinklers.