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WASTE DISCHARGE REQUIREMENTS FOR Page 2 SAN JOAQUIN COUNTY AND THE CITY OF TRACY CORRAL HOLLOW SANITARY LANDFILL CLASS III LANDFILL SAN JOAQUIN COUNTY 6. Land within 1000 feet of the facility is used for pasture land with a small amount of agriculture. 7. There are several faults in the area of the landfill. These include the Tesla Fault, the Livermore Fault, and the Calaveras Fault. The fault that .would most likely be the source of the maximum probable earthquake (MPE) is the Calaveras Fault. The MPE for this fault was calculated by Kleinfelder & Associates in a report called "Geologic Investigation, Foothill Sanitary Landfill, San Joaquin County, March 1988". The value of the MPE was given as 7.0 on the Richter scale. This would produce a maximum average peak horizontal ground acceleration of 0.208. 8. There are three distinct alluvial units underlying the site. The upper unit immediately underlying the landfill consists of semi -consolidated sand -gravel mixtures from 1 to 10 feet thick. Underlying these is the Corcoran clay which is approximately 50 feet thick beneath the east side of the site, and thins rapidly and pinches out near the western edge of the site. The lowest unit is a clay -sand matrix ._supported gravel which is att-least 200 feet thick. 9. The first water bearing formation is approximately 200 feet below the base of the landfill. The hydraulic gradient is generally to the southeast. A perched zone exists in the upper half of the Corcoran clay at a depth of approximately 20 feet. 10. The beneficial uses of groundwater are domestic, municipal, agricultural, and industrial supply. 11. The facility receives an average of 8 inches of precipitation per year. 12. The 100 -year, 24-hour precipitation event for the facility is 2.3 inches, as calculated by the Department of Water Resources (DWR) from precipitation readings collected at the Tracy 2 SSE weather -station. 13. A small strip of the facility along the southeast perimeter is within a 100 -year floodplain. However, the Discharger plans to install asphalt concrete flood protection which will prevent inundation or washout of waste management units due to floods with a 100 -year return period. 14. Surface drainage is to Corral Hollow Creek, an intermitent stream. 15. The beneficial uses of surface waters are domestic, municipal, agricultural, and industrial supply; ground water recharge; esthetic enjoyment; and preservation and enhancement of fish, wildlife and other aquatic resources.