SU0004002 SSNL - Laserfiche WebLink

Home Browse Search

structure to be built. The office building septic system sizing criteria will be based upon the formula found in the San Joaquin County Sewage Standards Handbook, where the Base Tank Capacity (BTC)+ Average Daily Flow(ADF)=Lineal Feet of Leachline: 1,200 gals BTC+ 5 people (parking stalls) x 30 gal ADF = 1,350 gals. 1,350 x 0.250 =3381ineal feet of leach line, two feet wide. It is recommended to install 4- 100 foot sections of Ieachline pipe. It is important to note that all septic systems have a lifespan. From the repairs and additions on record at the Environmental Health Department,it is evident the septic systems in this area have a definite lifespan. Due to the indigenous on-site clayey soils, the septic systems for this project will eventually fail. This time span is unknown and could he a few years to a few decades. The lifespan is dependant upon several factors. For example, if water softeners are used,the high sodium content of the septic effluent will cause the clays soils to "bind-up" and lose infiltrative and percolative capacity rather quickly. Therefore,they are not recommended. When a failure occurs, consideration should be given to installing a filter bed or mound system. Although more expensive, these "above ground" leachfield systems can add significant longevity to the septic systems for both Parcels. Replacement areas must be designated for the homesite parcel (at least a 50%replacement area) and a 100%replacement area for the commercial office building. Septic system leachline failure may also result from the advanced formation of a"biomat" or "clogging mat" on the wetted soil/effluent interface. This mat is composed mostly of aerobic and anaerobic bacteria and bacterial products consisting of a slime of polyuronides and polysaccharides. If the soil/effluent interface is well aerated, a variety of soil microfauna such as nematodes and protozoa may digest the clogging mat bacteria. Since the shallow subsurface soils consist of clay soil material, anaerobic conditions will prevail, which may theoretically hasten leachfield failure. The nitrate concentrations determined in the underlying groundwater indicates there has been impact to the deeper aquifers and can be attributable to upgradient agricultural fertilizer inputs. Regardless of the nitrate concentration of any well water in rural areas, it is recommended that bottled water should always be used for drinking and cooking purposes. It is recommended that if any structure with a septic system is built on the Designated Remainder, there should be a percolation test done in the area of the proposed leachfield. A shallow perc test at 42 inches should be conducted in the proposed leachfield area. In addition, the leachfield must be hydraulically protected during the rainy season to prevent inundation. A 50% standby replacement area must be incorporated into the design. All related septic system structures and a possible new domestic well must comply with the published"distance" requirements from property borders,roads, irrigation fields, etc. Page -4- Valley Ag Research