Erosion below the end of a box culvert led to unstable bank conditions and had drastically degraded a creek bed in Napa County. Thunder Mountain’s skilled artisans constructed an engineered solution designed to mitigate scour, restore vegetated banks and support aquatic life.

Because the only access to the sensitive creek area was from a bridge above the box culvert, operators had to carefully lower excavation equipment into the creek each day using a Cat 320.

Under the oversight of a biologist, workers hand placed native boulders as large as 2 tons to create a series of scour pools and grade control structures. A grouted rock structure was constructed immediately downstream of the box culvert. The creek banks were regraded and armored with riprap from the toe of the bank up approximately 30′. Live willow stakes were harvested downstream and placed throughout the riprap area. The tops of the banks were revegetated with a native plant seed mix and alder dee-pot plugs.

A landslide in Trinity County completely covered the county road. The failure was linked to massive groundwater seeping out of the hill, creating an unstable mud mass. Thunder Mountain solved the problem and repaired the slide by installing deep drains excavated into the slope and drained underneath the road section. Brow ditches were installed at the top of the scarp to divert flow on to the slope. Spoil was hauled away, slope contours restored and the slope treated with erosion control measures.

A homeowner in Citrus Heights was looking for a decorative driveway surface that was less expensive than concrete, but wouldn’t ravel or erode like gravel or decomposed granite. He found what he was looking for with Thunder Mountain’s Polymer Stabilized Road Surface, a combination of proprietary polymer and a decorative material called “Sonoma Gold Path Fines”. The result was a solid all-weather drivable surface, cool and pleasing to the eye.

Peterson Ranch in Suisun, CA is a housing development recently built out by K Hovnanian Homes. The site discharges to a wetland to the south that eventually runs into Suisun Bay. Fairfield Suisun has stricter guidelines due to the Suisun Bay water quality concerns.

The site is relatively flat but the soils are very fine colloidal clays. Thunder Mountain designed this advanced treatment system to protect the wetland that flows to Suisun Bay during wet season construction, resulting in a clean outflow less than 10 NTU.

A shallow landslide in El Dorado County threatened an EID water line in steep terrain. Georgetown Divide Utilities District had to repair in the wet season to avoid catastrophic failure.

Access was limited to a 3 mile unpaved road, making it difficult for trucks and equipment to get in and out. Haul trucks were prone to getting stuck in the mud, especially with the heavy rains.

Thunder Mountain constructed a gabion box wall to permanently stabilize the slope. Despite numerous challenges, construction was completed in only 3 weeks.

A residential rain water harvesting system was placed under a large patio in back yard. Thunder Mountain designed the retention tank, which can be used for irrigation and emergency water source in case of fire. The retention tank, when full, overflows into a secondary detention tank where the water can infiltrate and recharge the water table. Rainwater enters the tank through pervious pavers and filtered water from roof downspouts. The tanks can collect and infiltrate as much as 60,000 gallons of rain water per year.

Thunder Mountain installed drilled soil nails with reinforced wire and shotcrete surface to stabilize an oversteepened bank, protecting a permanent road section and providing access to an existing geothermal energy well.

Caltrans called on Thunder Mountain to perform emergency slide repair on Highway 70, using conventional slope repair methods including slope excavation and hydroseeding.