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3-5 mitigate rupture of a Holocene fault. A potential fault, referred to as the Stockton Fault, is an east -west trending feature derived from oil well data projected to underlie the project site. The Stockton fault defines the northern edge of the Stockton Arch, a basement rock that divides the San Joaquin Basin on the south from the Sacramento Basin on the north. The Stockton fault is an inferred fault and considered not active. The most significant cluster of active faults are the San Andres, Calaveras, Hayward, Antioch, and Green Valley faults located 30 to 70 miles west of the project site. The nearest active fault is the Great Valley 7 fault located approximately 21 miles from the project site. The Great Valley fault is a reverse fault with a 15 -degree dip and an approximate fault length of 45 km. The slip rate is estimated at 1.5 mm/year. The seismic exposure of Forward Landfill was evaluated by Geosyntec Consultants ([Geosyntec], 2001). The evaluation consisted of assessment of seismic hazards near the site and development of corresponding design ground motions. In order to assess the seismic loads that may occur at the site following regional earthquakes, Geosyntec reviewed available information regarding significant active and potentially active faults and seismic source zones within 100 miles of the project site (Table 4). Also listed in Table 4 are the strong ground shaking duration (Ds) and Peak Horizontal Ground Acceleration (PHGA) estimates for both the maximum probable earthquake (MPE) and the maximum credible earthquake (MCE) events. Both estimates are for a hypothetical bedrock outcrop at the geometric center of Forward Landfill. As shown on Table 4, the Great Valley (Segment 7) blind thrust fault system, approximately 21 miles southwest of the site, has the greatest potential to generate large earthquake loads at the Forward Landfill. A MPE moment magnitude (Mw) 6.4 earthquake on the Great Valley fault with its associated 11.8 seconds of duration of strong ground shaking would produce a PGHA of approximately 0.09g; a MCE Mw 6.7 event on the Great Valley fault would generate a PHGA of approximately 0.13g with an upper bound horizontal ground acceleration of 0.158. Based on the deterministic PHGA from the MCE of 0.138, the PHGA from the MPE of 0.068, and the largest historic ground acceleration of 0.078, GLA identified a site design horizontal ground acceleration of 0.158 to be used for seismic design of the facility based on the MCE event of 6.7 on the Great Valley fault (Segment 7). While the Great Valley fault was calculated to yield the highest PHGA, the duration of earthquake -induced ground shaking would be longest for the San Andreas fault system. The MPE and MCE on the San Andreas fault system are characterized by the same Mw 7.9 event at a distance of approximately 70 miles. As shown on Table 4, such a large -magnitude distant event is calculated to induce strong ground shaking that could last 45.4 seconds. Given the relatively small difference in the estimated bedrock PHGA and the relatively large difference in estimated Ds, Geosyntec concluded that the Mw 7.9 event on the San Andreas fault system could be the most damaging earthquake for Forward Landfill. Accordingly, the Forward Landfill SWT Engineering Joint Technical Document - April 2014 z:\projects\allied waste\forward\five year permit rvw 2013\jtd-5 yr pr 2013\text\sec 3_final.doc