SR0085493_SSNL - Laserfiche WebLink

Home Browse Search

Soil Suitability /Nitrate Loading Study Irerracon ALL STAR HEAVY HAUL & TOWING INCORPORATED Tracy, California July 1, 2022 Terracon Project No. NA217024 1.6.4 Condition of Borings after Presaturation All borings were dry and intact after the 24-hour pre-soak period. 1.6.5 Percolation Test Procedure Percolation tests were conducted for the borings on June 14th, 2022 in accordance with the requirements of the San Joaquin County EHD. The tests were observed by Mr. Ahmed from the EHD. Measurement of the water level during the percolation tests was from a fixed reference point on the PVC casing using a calibrated Solinst electric water level detector with a depth accuracy of 0.01 feet. All tabulated values on the field data sheet (Appendix E) are in decimal feet. After water drop was observed, the holes were checked and refilled as necessary to maintain approximately 0.5 feet (6 inches) of water above the top of grave!. The readings were recorded every 30 minutes for a period of approximately 4 hours or until the EHD representative arrived to witness the tests. The EHD representative directed Terracon to use the last reading on the percolation tests to calculate the percolation rate. 1.6.6 Percolation Test Forms and Results A shallow percolation test is defined by the EHD as being between 36 and 42 inches in depth. While a deep percolation test is defined by the EHD as being between 42 inches and 25 feet in depth. The shallow percolation test must demonstrate a satisfactory percolation rate of less than or equal to 60 minutes per inch drop in water level within the existing septic system disposal field of a parcel to utilize a standard septic system and 30 minutes per inch or less for septic pits. Details of the percolation tests are summarized in the table below. Table 7. Summary of Percolation Test. Test No. Percolation Percolation Rate Approximate Test Comments June 14th, 2022 Test Depth (min/in) Duration (see note) (feet) (hours) B1 23.4 83.33 4 Unsatisfactory 132 9.00 6.58 4 Satisfactory B3 3.32 19.23 4 Satisfactory Note: A satisfactory percolation rate is 60 minutes per inch or less for shallow leach lines and 30 minutes per inch or less for septic pits per San Joaquin County Onsite Wastewater Treatment Systems Standards (EHD 42-014), January 2017. 1.6.7 Discussion of Percolation Test Results Based on the percolation tests results, the percolation test borings B2 at 9.00 feet and B3 at 3.32 feet bgs demonstrated satisfactory percolation rates. According to the OWTS Standards Table 1.10.2, for percolation rates between 5 minute per inch and less than or equal to 30 minutes per inch, a minimum 8 -foot separation is required from the bottom of the dispersal system to Responsive ■ Resourceful ■ Reliable 13