CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARDSAN FRANCISCO Bi\Y REGION

ORDER NO. 87-047

WASTE DISCHARGE REQUIREMENTS FOR

BROWNING-FERRIS INIXJSTRIESCORINDA lOS TRANCOS IANDFILLOX MOUNTAIN RANCHHALF MOON Bi\Y, SAN MATEO COUNTY

'Ihe california Regional water Quality Control Board, San Francisco Bay Region,hereinafter called the Board, finds that:

1. 'Ihe Board on June 15, 1976, adopted Order No. 76-70 prescribing wastediscl1al:ge requirements for Browning-Ferris Industries, formerly knOVJJl asSan Mateo County Scavenger Company, hereinafter called the discl1al:ger,for the Corinda IDs Trancos landfill in the OX Mountain ranch.

2. 'Ihe discl1al:ger by application dated March 31, 1986, and amendments datedApril 28, 1986, and January 5, 1987 has applied for revision of theircurrent waste Discl1al:ge Requirements (WDR), in order to comply withTitle 23, Chapter 3, Subchapter 15 of the california Administrative Code,hereinafter called Subchapter 15.

3. 'Ihe discl1al:ger accepts approxiroately 2,200 tons per day of nonhazardoussolid waste consisting of municipal, industrial and agricultural refUSe.No liquid wastes (i.e. less than 50% solids), other than limited amountsof dewatered sewage sludge, can be disposed at this site.

4. 'Ihe active San Andreas fault is located approxiroately 2.5 miles to theeast, the active Seal Cove fault is located approxiroately 4.5 miles tothe west, and the potentially active Pilarcitos fault is locatedapproxiroately 1.3 miles to the east. 'Ihere is no known active faultwithin the landfill site. 'Ihe site meets the siting requirementscontained in Title 23, Chapter 3, Subchapter 15 of the californiaAdministrative Code (Subchapter 15) that prohibit siting Class IIIlandfills on a Holocene fault.

5. 'Ihe landfill is in a steepwalled canyon approxiroately 4.5 miles northeastof the town of Half Moon Bay. 'Ihe toe of the landfill is at approxiroately550 feet elevation, and the top of the fill will be at approxiroately 1100feet. 'Ihe site is underlain by granodiorite bedrock which is extensivelyfractured, faulted and weathered to depths of 100 feet or more.

6. Corinda IDs Trancos Creek was routed around the perimeter of the site in1984. Previously, the Creek flowed through a cu.lvert under the refUSefill. Runoff from the side walls of the canyon flow into the perimeterditch. 'Ihe perimeter ditch discl1al:ges into a settling pond, which inturn, discharges to the natural Corinda IDs Trancos Creek. 'Ihe Creekflows into Pilarcitos Creek south of Highway 92. Water still flowing in

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