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SPX Corporation incorporated into the Basin Plan. The Stockton Diverting Canal _ not connected to the Calaveras River during the dry period and therefore does not exchange water wit: tie Calaveras River during this period. We believe that during the dry period the Canal should not be cons:L.'red part of the Calaveras River. ✓ Application of the drinking water standards to the Stockton Dive—; Canal makes no sense. To the best of our knowledge no drinking water intakes are downstream of the MCTC discharge. The Canal is essentially dry during 6 months of the year and therefore the Canal is an unre-le drinking water supply. ✓ Groundwater is a source of drinking and irrigation water supplies zownstream of MCTC discharge and in the vicinity of the Stockton Diverting Canal and the MCTC facili As the RWQCB has noted during the dry period the MCTC discharge evaporates and/or percolates to He groundwater, which is a source of drinking and irrigation water. The RWQCB also agrees that the --aturally occurring groundwater TDS levels are higher than the 500 mg/1 limit proposed for the MC—,: wastewater discharge permit. If the groundwater that is used for drinking and irrigation has TDS level =eater than 500 mg 1. it makes no sense for RWQCB to require the MCTC discharge cleanup the natura:: xcurring levels of TDS that obviously have not adversely impacted the use of groundwater for drinking -=irigation. We are submitting specific comments on the conditions, monitoring, lits::= and terms of the tentative wastewater discharge requirements as follows: • Findings: ➢ Item 2: MCTC has ceased all operations at the facility exce`: -or the operation of the Groundwater Extraction and Treatment System. ➢ Item 4: Because an impermeable cap was placed over the con?--.inated soil area, we believe that the requirement for reinjecting 5% of the treated water into the shaicw soil to flush contaminants defeats the purpose of an impermeable cap and should therefore be eliminate;_ 3etuming 5% of the-treated water will not have a significant impact on minimizing the dewatering of the as-Mier. • Item 19: The Stockton Diverting Canal is a man-made canal cos_xted to divert the natural river flow to provide irrigation water and flood control from October 1 to Apr _ of each year. During the period from April 1 to October 1 of each year the Stockton Diverting Canal has plaited or no flow except for the MCTC Stockton CA wastewater discharge. If the MCTC, Stockton C; facility wastewater discharge were eliminated there would be no aquatic organisms because there mould be insufficient water to support aquatic life. Therefore, we believe that establishing the effluent '----s for Copper (Cu) 'cased on the acute and/or chronic aquatic life toxicity without the dilution is in_.^ropriate. The dilution factor of the Calaveras River should be the appropriate dilution factor, i.e. the nt at which the Canal reconnects with the Calaveras River. The purpose of the groundwater extraction �d treatment system is to cleanup the groundwater and capping the contaminated soil areas was intended:o prevent stormwater contamination. In fact, a pilot test of an insitu groundwater treatment is planned that=ay lead to cleanup of the contaminated groundwater to meet the groundwater quality criteria in the next ' vears. The discharge will then cease and the Stockton Diverting Canal will be dry each year during A7-- : to October 1. We do not believe that MCTC should be required to maintain an unnatural aquatic env, c—ent. Therefore, we don't think that it is appropriate to impose the Cu limit based on acute and chronic -,:aric toxicity criteria for the undiluted waste discharge. In addition, aquatic toxicity testing to date _as demonstrated that the discharge consistantly meets the criteria. ➢ Item 20: Our objections to the proposed new limit Cr-6based on:he acute and chronic aquatic toxicity are the same as our objections for the proposed new Cu limit. ➢ Item 23: See previous comments on pages 1 and 2. • Monitoring Requirements ➢ Influent Monitoring: We have been operating the groundwaw extraction and treaanent system and monitoring the groundwater and the influent to the treatment s}s m for over 10 year. We believe the Page 2 of J 01/C C:\WINDOWS\TEMPWrafl NPDES wmmenu.Jrc