Eureka, Humboldt County, California
CAInc prepared a Geotechnical Report for Phase C of the trail, located along the Humboldt Bay waterfront. The trail section is approximately 6,200 ft long and spans “Wedge Slough”, then follows the shoreline of the bay along an elevated fill area and crosses an environmentally sensitive marsh. The trail alignment continues southeast along the margin of Eureka Slough and crosses the NCRA Railroad and “Target Slough”. The trail continues south under Highway 101 before spanning First Slough adjacent to the Shoreline RV Park. After continuing southwest between Second Slough and the RV park, the trail bends west along a pump station access road where it continues west until reaching TYDD Street. The proposed trail structures consist of:
- A 113-ft. long, single span bridge over “Wedge Slough”,
- Approximately 530-ft. of raised walkway (boardwalk) over the environmentally sensitive marsh area,
- A 80-ft. long, single span bridge over “Target Slough”, and
- A 67-ft. long, single span bridge over “First Slough”.
The bridges are each expected to be prefabricated, aluminum structures with abutments embedded at least 2 ft below existing ground surface elevation. Due to the lightly-loaded structures and ground sensitivity to heavy equipment, the bridge abutments will be reinforced concrete shallow spread footings, subject to the limitations discussed herein. Plan footing dimensions are indicated to be approximately 6 ft. by 12 ft. Total loads on the abutment footings are expected to be on the order of 400-500 pounds per square foot (psf).
The boardwalk is about 530 ft long with deck grade about 3 feet above ground surface (about one foot above high tide). Since this crosses the environmentally-sensitive marshland, design and construction is intended to minimize ground disturbance.
To prepare the report, CAInc reviewed available geologic, soils, and seismic maps; drilled and sampled test borings; hand augured test borings; and performed geotechnical engineering calculations and analysis to develop recommendations. CAInc analyzed subsurface conditions, completed lab testing, determined corrosion potential, and provided seismic design parameters. Recommendations were provided for spread footings and helical piles.
Tulare County, California
The Earlimart Park is located on 3.5 acres in the Earlimart community located in southwest Tulare County. The planned park project will include an open turf play area, a children’s play area, community artwork, barbeque area, picnic area, and a biofiltration swale. CAInc prepared a Geotechnical Report for the project, which included analysis of subsurface conditions and seismic considerations. Provided recommendations for infiltration rates for the biofiltration swale; grading and fill placement; landscape suitability; utility trenches; and concrete flatwork. Also prepared a Foundation Memorandum to include the design of a shade structure in the final park design. The 109’ by 65’ shade structure will be supported on shallow spread footings and concrete slab on grade.
South Lake Tahoe, El Dorado County, CA
This is the second implementation phase of the South Tahoe Greenway Shared Use Trail Project. It will cross barriers and close gaps in the bicycle network to form the major north/south connection in the City of South Lake Tahoe. The Project constructs approximately 0.95 miles of American Association of State Highway and Transportation Officials (AASHTO) compliant trail, including approximately 0.8 miles of ten feet wide asphalt concrete trail and approximately 0.2 miles of elevated boardwalk/bridge. A new shared-use bridge over Trout Creek, improved local street crossings, and interpretive/wayfinding signage are also part of the project. The first implementation phase of the Greenway, Phase 1A, was constructed in 2015. This project is identified within Tahoe Regional Planning Agency’s (TRPA) Environmental Improvement Program. CAInc conducted a geotechnical investigation for the project, including drilling, sampling, and logging of test borings and performing laboratory testing on the samples. Performed geotechnical engineering analysis for design and construction of the trail segments, boardwalk elements, and foundation elements for the proposed pedestrian bridge crossing at Trout Creek.