SR0084095_SSNL - Laserfiche WebLink

Home Browse Search

In summary, the soils testing and investigation has found the indigenous soils under the proposed effluent disposal area to contain a predominately fine-grained sandy, silty (sandy loam) material. The soil has favorable permeability characteristics with some nitrate mitigation capabilities based upon soil chemistry analysis. II. SOIL SUITABILITY STUDY FINDINGS A. SUBJECT PROPERTY AND SURROUNDING STUDY AREA INFORMATION SSS§ 1.1 As noted on the San Joaquin County Parcel Viewer Maps, the current surrounding land use is composed primarily of agricultural production land in permanent crops to the north south, east and west. Surrounding land has been in agricultural production for many decades. The property is zoned AG-40. SSS§ 3.1,3.2, 3.3,3.4, 3.5,3.6 Applications with the EHD reveal that there have been no permits issued for repairs/additions to existing systems within a one-half mile surrounding the project site. This can be attributed to the very low density housing and the silty-sandy indigenous soils. The project site has relatively level terrain; consequently, there was no need to incorporate design considerations for slopes within the wastewater disposal area. Nor is there a dramatic elevational difference between the proposed restrooms and the proposed disposal field area. B. SOIL PHYSICAL CHARACTERISTICS AND ANALYTICAL TEST RESULTS SSS§ 5.2. The United States Department of Agriculture - Soil Conservation Service (USDA-SCS) indicates the on-site soils to consist of a Veritas fine sandy loam (#266). This soil type correlates with the soil type encountered. It is highly unlikely significant hardpan exists in this locale due to the fact there are orchards throughout this area that are thriving. Rust mottling was not observed in the perc test boring which would be indicative of seasonal soil saturation. NLS§ 1.1, 1.2. As noted on the A&L Laboratory Soil Analysis Reports found in Appendix C, chemical analyses of the soil sample from the perc test soil boring quantify the constituents that influence nitrate loading from this project. The important parameters for nitrate loading assessment are the organic matter, pH, cation exchange capacity (CEC), and nitrate-nitrogen content. The nitrate-nitrogen and organic matter concentrations are low at the 42-inch depth. This suggests a low potential for future nitrate-nitrogen loading from indigenous nitrogen content within the soil. Since septic effluent is composed predominately of ammonium (NH4), the pH, along with the CEC, are significant influences on ammonium molecules. The pH of the soil is acidic which will inhibit ammonia formation and promote ammonium formation. There is sufficient clay and organic matter in the soil for ammonium molecules to adsorb to these particles for microbial uptake. The Cation Exchange Capacity of the soil is relatively low at the sampled depth, which would be indicative of the soil type. 2 Chesney Consulting