COMPLIANCE INFO_NL STDY - Laserfiche WebLink

Home Browse Search

' Performa Inc. • • May 7,2003 Page 9 Table 4. Summary of the general mineral analytical results. Constituent Concentration MCL Total Filterable Residue @180C 590 (TDS) MBAS ND ' MCL-Maximum contaminate limit established for drinking water. The two water samples varied greatly in nitrate concentration between March 24 and May 1, ' 2003 ranging between 18 mg/L as NO3 and 163 mg/L as NO3 . The MCL for nitrate in drinking water is 45 mg/L as NO3. Boring B-1,where both samples were collected, was located about 55 east of the closest leach line in the septic field. It is possible that the concentration of nitrate in the first ground water may be influenced by the proximity of the septic field(55 feet away). It is also possible that changing ground-water direction, gradient, or perhaps recent rain infiltration may cause the variations observed. ' 6.0 NITRATE LOADING STUDY 6.1 Hantzsche and Finnemore's Approach to Estimating Nitrate Impacts to Ground Water Because of the concern of nitrate leaching into ground water from septic systems, a nitrate ' loading analysis was required by the San Joaquin County EHD, for the proposed trucking facility to measure the potential concentration of percolating effluent and rain fall over the long term. If the percolating effluent and rain water reach the aquifer, ground water quality may be impacted to some degree. The method utilized for the nitrate loading analysis is based on a simple mass balance formula, ' discussed in a published article by Hantzsche and Finnemore(1992), which provides a convenient and simplified method to estimate long-term ground-water nitrate impacts on an area- wide basis. Hantzsche and Finnemore found that over a long period of time, water quality in the upper saturated ground-water zone closely approximates the quality of percolating recharge waters. They believe that their method is a good planning tool and provides useful information to planners and local officials but with some real limitations specifically; "...the equation ignores dispersion, lateral flow, and mixing with ground water flow from up-gradient areas. These processes would generally contribute to additional reduction of nitrate-nitrogen concentrations in N O �SSO L\