Hard Rock Grinding & Rental

Here we were in Rocklin CA, Target and Walmart store parking lot.

We heard about the project and contacted the contractor to see if we could be of service. The sub-contractor was not happy with the current production from conventional excavator mount hammer. It was quickly apparent that the rock was so hard it was mushrooming a breaker point each day. Contractor was concern with production and the budget for consumables parts.

The contractor asked us to meet onsite. We brought our Silver Schmidt PSI rock tester to analyze rock compressive strength. After the testing, we knew we had right tool for the job, with much lower cost for consumables attack picks vs. breaker point.

The contractor approved us to move-in our operated rental machine with cutter to complete the remaining 130 - 5ftx5ft hole 6ft deep in 12,000psi granite bedrock.

The project was demanding due to the straight plunge into rock with the cutter, but was ultimately the perfect tool for the project and completing project as expected and within budget for the sub-contractor and ultimately the owner.

The breaker method: 8hrs per 1 hole and replacement of 1 breaker point per hole ($1,400).

The rock grinder method: 3.5hrs per hole and replacement of 3 to 5 attack picks per hole. ($90 to $150).

Hard Rock Grinding & Rentals, Inc.

Large residential foundation GRIND!!!!
Project is in Chico, California.

This project went through extensive rock mitigation review with the general contractor, architect, and owner. The strength of the native material and refusal by conventional track excavator bucket pushed the contractor to seek other methods of removal.

Blasting was considered, but was not an option due to nearby residents. After comparable methods were considered, Hard Rock Grinding & Rentals was hired to perform the mass excavation and footings removal using a TCU or Transverse Cutter Unit. The deciding factors was due to the speed of equipment mobilization to job site from Hard Rock Grinding & Rentals, the TCU removal rate per hour and byproduct the cutter produced.

Hard Rock Grinding & Rentals, operated a 160hp cutter unit with carbide tip attack picks, commissioned to a Cat 330c, 80,000lbs track excavator with auxiliary hydraulics. The expected removal rates were in the low teens per hour. The actual rate of removal in the mass excavation was 13 to 17 yards per hour. When it came to the footings, the TCU was extremely flexible in lining up with footing layout.

Extra bonus was a clean cut to trench walls, saving in considerable concrete cost due to no over brake unlike a hydraulic hammer.

This project had a large retaining walls system needing approved back fill. All of the spoils for this project was re-use for padding and retaining wall back fill. (See photo of spoils).

No export of broke rock and no import of suitable back fill materials, saving thousands in trucking cost!

Removing Conejo volcanic rock in preparation for multiple concrete spillway segments.