SU0004324 - Laserfiche WebLink

Home Browse Search

1 . INTRODUCTION ChoncAAcs Diyu;e Desserts ('Chocoholics) produces chocolate desserts and candies at a Clements, California production site. The primary onsite wastewater leach field has exhibited far less infiltration capacitl than the design specification. The purpose of this evaluation was to determine the cause of the primas leach field failure,provide recommendations for repairs, and provide related recommendations for overall%vastew,ater sastem improvements as deemed appropriate. Issues relating to die secondary leach field,odors, biochemical oxygen demand (BOD) loading, and a reserve wastewater area are also addressed. 2 . BACKGROUND The histom of wastewater system planning, design, construction, and performance are summarized to provide contest for the evaluation of the wastewater system. 2.1 Punning and Design A soil suitability study and septic system design wvas originally performed by Chesney Consulting(2002). The _ soil suitability analysis included standard percolation tests and a double ring cylinder infiltrometer test for the near-surface soil. Percolation rates ranged from 35 minutes per inch for a 42-inch deep boring to only 4.6 minutes per inch for a 16-foot deep test boring. The infiltration rate calculated from the double ring infiltrorneter test was 43 minutes per inch. Following San Joaquin County Standards Consulting, Chesney recommended wastewater treatment consisting of a 1,300 gallon grease trap followed by a 3,000 gallon primary septic tank and a 1,200 gallon secondary - sepdc tank with effluent filters. Chesney recommended an 1,800 square foot primary dispersal field utilizing Infiltrator chambers.-Chesney rec6mmended secondary dispersal facilities consisting of two 40-foot leach lines, with a 36-inch diameter, and 16-foot deep seepage pit at the end of each leach line. Chesnev does not appear to have performed a characterization of wastewater strength nor considered the wastewater strength as a factor in the design.The initial design included an automatic distribution valve to split the flow equally over tithe between the primary-and secondary dispersal systems. The valve was later changed to a manual distribution valve upon request of Chocohohcs. Chesnev also performed an evaluation of the impacts to groundwater from wastewater nitrogen loaditgs. The estunated nitrate-N concentration, including the effects of denitrification and rainwater dilution,ins less than the 10 milligrams per liter (mg/].) drinkingwater lunit. Chesncv recommended the Infiltrator chtrnbers- be placed at a relatively shallow depth to enhance the opportumn for plant uptake of nitrate. ^iihtlsebal A: i=..;,