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exceed the USEPA drinking water standard secondary maximum contaminant level of

0.3 mg/l. Spring SP-2 is located west of the Whitney Canyon fault in the northwestern
portion of the project property in an area of active tar seeps. Staining, resembling rust, was
noted on nearby rock formations during sampling activities at this location. Such stains
indicate natural oxidation of dissolved ferrous ion to ferric ion (Fe" " ”), as ferrous ion-rich
water flows away from the source (SP-2 spring), thus precipitating ferric iron oxides in
nearby rocks.

9.4 LOCAL HYDROGEOLOGIC MODEL

Local geology and topographic relief are the primary controls in the occurrence and flow
of groundwater at the project property. The combination of these two factors also
influences recharge/discharge areas and conditions, hydraulic gradients, and hydraulic

relationships among aquifers and aquitards at the property. The local hydrologic regime is
also affected to some degree by naturally occurring petroleum and petroleum-related waters.
Major components and characteristics of the conceptual local hydrogeologic model are
discussed in the following sections.

9.4.1 Prinoipgl Water-Eating Rooks

As discussed in Section 8.0, important fresh-water aquifers of the Eastern Hydrographic
Subarea consist of thick, poorly consolidated Saugus Formation deposits, and overlying
alluvium principally found within the Santa Clara River drainage and its major tributaries
(Slade, 1986; 1988). However, these units essentially are either not present at the project

property, in the case of the Saugus Formation, or are represented by shallow, areally limited
deposits within stream drainages, in the case of alluvium. Thus, the principal water-bearing
rocks within the project property are instead represented by fractured, crystalline San
Gabriel Formation rocks and Eocene sedimentary deposits.

San Gabriel Formation: Groundwater occurs within secondary fracture porosity developed
in the San Gabriel Formation, as the rock mass contains little or no primary porosity. The
San Gabriel Formation is characterized by an interconnected fracture network of variable
density. Drilling data and field mapping of fractures do not indicate a dominant orientation
to fractures; however, lineaments observed in aerial photographs suggest that both
northwest-southeast oriented and northeast-southwest oriented fractures may be present.

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