SU0008143 SSNL - Laserfiche WebLink

Home Browse Search

CONCLUSIONS AND RECOMMENDATIONS In summary, the soil conditions examined near the location of the septic system drain field appear to be suitable. A satisfactory soil percolation rate of 42 minutes per inch was observed. The depth of ground water based on recent aquifer levels is relatively shallow and approximately 31 to 33 feet below the ground surface. The ground-water flow direction is to the southwest at a rate of 13 to 15 feet per mile in the vicinity of the Site. The on-site domestic water well was tested for nitrate and DBCP. Nitrate was detected in the water sample at a concentration of 16.9 mg/L-NO3, well below the Maximum Contaminant Level (MCL) set by the US EPA of 45 mg/L-NO3- DBCP was detected in the water sample at a concentration of 0.1 µg/L, below the MCL of 0.2 µg/L. It is our opinion that the use of on-site septic tanks and drain field systems on the Site will not likely cause a buildup of nitrate in the aquifer above 10.0 mg/L-N. By utilizing the Hantzsche and Finnemore (1992) equation, the resulting concentration of effluent is 14.68 mg/L-N. The US EPA uses 10 mg/L-N as the drinking water recommendation for / l nitrate as nitrogen; this level is used here as a marker to measure potential impact to the aquifer. The equation is very conservative, does not take into account mixing within ground water, and is sensitive to small site sizes. We have presented several other reasons why we do not believe the aquifer will experience a buildup of nitrates. See the section Discussion of Nitrate Loading Results for more discussion. We believe the Site suitable for development with the use of standard septic systems. We would, however, recommend any new septic tanks installed on the property be, '1 oversized to increase tank retention time that will improve overall water qualms. This will hep of mcigate'any potential impacts to ground water. LOGE1013 Page 14