Triangle Rock Culverts Project

2 Documents in Project


SCH Number
Lead Agency
San Luis Water District
Document Title
Triangle Rock Culverts Project
Document Type
MND - Mitigated Negative Declaration
Present Land Use
A1 - General Agriculture/Agriculture
Document Description
The Triangle Rock Products Los Banos facility currently uses and maintains two existing dry creek crossings over Los Banos Creek. The dry creek crossings are permitted via an existing Streambed Alteration Agreement (SAA; File No. R4-2001-0098D). The creek crossings can only be used when the creek is dry pursuant to the terms of the existing SAA. Periodic water releases from Los Banos Creek Detention Dam between September and March close the creek crossings, and cut off vehicle access between resource recovery sites and the processing facility when the road is inundated by creek flow. The proposed Project will install two culvert pipes at the south crossing and three culvert pipes at the north crossing to divert flow under the improved access road to facilitate year-round vehicle use of the road. The construction of the culverts will occur at the two locations (Project Area) where the access roads for the existing quarry intersect with Los Banos Creek. The Project will install culverts at each location to divert flow under the road. These culverts will be designed to handle a capacity of 450 cubic feet per second (cfs) at the southern crossing and 150 cfs for the northern crossing. The difference in the design flow between the two crossings is associated with the diversion into the Delta Mendota Canal located upstream of the northern crossing. Project construction will occur within the existing road, the Ordinary High Water Mark (OHWM) and top of bank (TOB) of Los Banos Creek. The construction staging area will be outside of any sensitive habitat areas or waterways. Temporary access within the watercourse will be required for the grading of the road and installation of the culverts. The Project will generally require minor grading and excavation of earth in Los Banos Creek in order to prepare the Project Area for construction of culverts under the road crossing. The amount of earthwork will require a Stormwater Pollution Prevention Plan (SWPPP). A subbase will be installed to support the culvert. The pipes will be lifted into place and then backfilled to the roadway grade. Lastly the roadway surface will be installed. The road will be bermed with the placement of fill and raised banks will be approximately three feet high from the road surface. The road edges bound by Los Banos Creek will be reinforced and improved with rock and gravel to prevent the creek from overtopping the road. Installation of corrugated metal culverts will require excavation of the road for improvements, placement of fill to elevate the road, installation of culverts and placement of gravel and rock along road edges for reinforcement. The Project will require the use of a backhoe, excavator, trenchers, crawler tractors, and dump trucks, which will be staged outside of Regional Water Quality Control Board (RWQCB) and United States Army Corps of Engineers (USACE) jurisdiction in developed areas of the existing facility.

Contact Information

Steven Stadler, PE
Agency Name
San Luis Water District
Job Title
District Engineer
Contact Types
Lead/Public Agency

Amy Wilson
Agency Name
Provost & Pritchard Consulting
Job Title
Environmental Project Manager
Contact Types
Consulting Firm


Los Banos
Northern California
Parcel #
083-210-022, and 088-070-002
Other Location Info
The Project is located in Merced County, California, approximately 111 miles south of Sacramento. The Project Area is located approximately on Assessor’s Parcel Number(s) 083-210-022, and 088-070-002. The proposed culvert locations are located within the existing Triangle Rock Plant/Facility/Quarry. The centroid of the northwest culvert Project Area is 37° 01’ 09.77” N, 120° 53’ 51.94” W. The centroid of the southeast culvert Project Area is 37° 00’ 36.69” N, 120° 54’ 16.66” W.

Notice of Completion

State Review Period Start
State Review Period End
State Reviewing Agencies
California Air Resources Board (ARB), California Department of Fish and Wildlife, Central Region 4 (CDFW), California Department of Parks and Recreation, California Department of Transportation, District 10 (DOT), California Department of Water Resources (DWR), California Native American Heritage Commission (NAHC), California Natural Resources Agency, California Regional Water Quality Control Board, Central Valley Fresno Region 5 (RWQCB), Central Valley Flood Protection Board, Department of Toxic Substances Control, Office of Historic Preservation, State Water Resources Control Board, Division of Drinking Water, State Water Resources Control Board, Division of Water Rights
Development Types
Other (Water Facilities Project - Culverts)
Local Actions
Water Facilities Project
Project Issues
Biological Resources, Cultural Resources, Cumulative Effects, Hydrology/Water Quality, Tribal Cultural Resources


Notice of Completion [NOC] Transmittal form

Disclaimer: The Governor’s Office of Planning and Research (OPR) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at or via phone at (916) 445-0613. For more information, please visit OPR’s Accessibility Site.

Download CSV Download All Attachments New Search Print