McInnis Skatepark
San Rafael, CA

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Client: County of Marin, Parks and Open Space 

This 25,000  square foot skatepark  made great use of a former quarry area  in San Rafael’s McInnis  Park.  Architects,  Indigo  / Hammond & Playle together  with Pro  skater  Kevin   Thatcher   created  the design  of this “awesome” recreation facility.

The great variety of features includes ramps, stairs with rails, stainless steel coping, a clover bowl, warlock with a volcano, and a major bowl with transitions from 7 to 10 feet high.

The old quarry site left a variety of geotechnical challenges to be met. In areas of old quarry waste new fills were stabilized by partial excavation and reinforcing the new fill with heavy plastic geogrids. Pockets of expansive soils were carefully excavated from the skatepark area and specially reconditioned to allow their use in the roadway and parking area.  

Boulders excavated from the site were used to construct a riprap buttress along the uphill side of the skatepark and to support a cut slope along the access driveway.

Throckmorton Fire Station
Mill Valley, CA

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Client: County of Marin 
Architect: C3 Design Alliance 

The new Throckmorton Ridge Fire Station is a three-engine-bay, rustic lodge-style facility located on the beautiful Panoramic Highway adjacent to Mount Tamalpais near Mill Valley. 

The building is located at the same site as an older obsolete structure. The initial geotechnical 
evaluation focused on the geologic setting, seismicity, identification of a cut-fill transition 
extending through the proposed building, and concerns about the stability of the steep fill 
slope below the site. 

We explored site conditions with test borings and prepared geotechnical recommendations and design criteria for the project.  These included a foundation system consisting of shallow spread footings on bedrock with drilled, piers on the downhill side of the building that extend through the fill into bedrock.

The steep fill slope below the site was found to have poor stability and was mitigated by excavating the weak soils, installing subdrains and reconstructing the slope with compacted fill. 

Additional services included evaluation of 1,200-feet of new sanitary sewer using test borings 
and test pits to determine excavation conditions in potentially variable Franciscan Mélange 
bedrock. 

Solano Juvenile 
Detention Facility
Fairfield, CA

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Client: Solano County
Architect: KMD Architects 

A new 90-bed juvenile detention facility built on a site occupied by an existing detention facility. The existing Juvenile Hall is located on a 5-acre portion in the northwest corner of the larger 18-acre Solano County campus. The campus is located at 2100 West Texas Street in Fairfield, California. The proposed 30,000 square-foot addition was built using concrete masonry unit (CMU) construction with a slab-on-grade floor. Other elements included parking lots, underground utilities, security walls, access roads, play courts and concrete walkways. 
 
Our geotechnical evaluation included the advancement of three borings, laboratory testing and development of geotechnical engineering parameters for design of the building foundations and grading recommendations. 

During exploration, we encountered moderately 
to highly expansive soils which placed a significant constraint on the foundation design. Of the alternatives to mitigate this condition, the client elected to over-excavate the top few feet 
of soil and replace with non-expansive engineered fill. 
 
During construction, we observed the foundation system preparation for the main building, which was built on a thickened reinforced concrete slab and security walls, which were constructed on a drilled pier foundation system. Additionally, we observed and tested subgrade for asphalt concrete paved parking lots and access roads.