SITE INFORMATION AND CORRESPONDENCE

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ORDERNO. 5-00-119. 2- INFORMATION SHEET GENERAL ORDER FOR DISCHARGE, TO SURFACE WATERS OF GROUND WATER FROM CLEANUP OF PETROLEUM FUEL POLLUTION ATTACHMENT C Salinity,Total Dissolved Solids,and Electrical Conductivity Salinity, total dissolved solids (TDS), and electrical conductivity.(EC) are measures of dissolved salts in water. Salinity is a measure of the mass fraction of salts (measured in parts per thousand),whereas TDS is a measure of the concentration of salts (measured in ma/1). Since the electrical conductivity(EC) of water generally changes proportionately to changes in dissolved salt concentrations;EC is a convenient surrogate measure for TDS. Receiving water bodies m.the Central Valley can contain significant seasonal, and wet weather related fluctuations in EC levels due to urban runoff and agricultural drainage. Federal regulations, 40 CFR Part 122,44 (d)(1)(i),require that NPDES permit effluent limitations must control all pollutants which are or may be discharged ata level which will cause or have the reasonable potential to cause or contribute to an in-stream excursion above.any State water quality standard,including any narrative criteria for water quality. Beneficial uses,together with their corresponding water quality objectives, can.be defined.p.er federal regulations as water quality standards. For municipal and domestic supply beneficial uses,federal and state promulgated maximum contaminant levels (MCL's) are appropriate minirnum water quality objectives. Furthermore,Delta waterways and portions of the San Joaquin River have been identified as Water Quality limited Segments, and are listed on the California CWA Section 303(d)List for elevated dissolved solids concentrations and elevated EC. The Basin Plan objectives set.receiving water objectives at 700 umhos/cm and 1000 umhos/cm for winter and summer periods,respectively. The CA Department of Health Services has established a Secondary maximum contaminant level (MCL) for EC ranging from 900 to 1,600 µmhos/cm. Due to the ephemeral nature of some of the Central Valley's receiving waters, and associated lack of receiving water assimilative capacity in other Delta waters,most proposed discharges have the reasonable potential to exceed, and cause the waters of the State to exceed,the lower limit of the DHS Secondary MCL water quality objective,potentially impacting the impacting -UN beneficial use. Additionally, elevated dissolved solids may.contribute to a failure of acute or chronic toxicity testing, and associated Basin Plan narrative toxicity criteria. Effluent Limits Development Effluent limits and receiving water limits have been established as follows: a. Effluent 30-Day Median Concentrations for TPH,Benzene,Toluene, Ethylbenzene, Xylene, and MTBE are established as `non-detectable',that is,less than the detection concentrations for specified, commonly available treatment and analytical technology.