SU0002173 SSNL - Laserfiche WebLink

Home Browse Search

kTJ KLEINFELDER drilling rig from our firm was used to drill several deep percolation holes. The following day additional percolation tests were performed and once again no drop in water level was measured. At this point it was apparent that the site was underlain by hardpan typical of the area and that an engineered or mound system would be needed to dispose of wastewater. We understand that Mr. Ernie Smith, a registered civil engineer, is providing the design directly to R&G Schatz Farms, Inc., fort is system. NITRATE LOADING CALCULATIONS We have been requested by PHS/EHD to calculate the nitrate loading for the proposed mound system. As you are aware, the drinking water standard for nitrate is 45 mg/1 as (NO3) and 10 mg/1 as Nitrogen (N). In our evaluation of nitrate loading, we have used the Hantzsche Mass Balance Equation (HMBE), which is presented below with an explanation for each factor and the value used in our study. We note that the Hantzsche waste balance equation is primarily for residential-type structures. Since the intent of this mass balance equation is to evaluate the impact on groundwater over a large area, we assume that the usage of the mound system by the approximately 3V2 employees during the approximate 3 month harvest season would constitute approximately % of a typical household. In other words, there would be no bathing, laundry, etc., and only limited use of a dishwasher in the small laboratory. Even if all of the employees used the restroom facilities 5 times per day for 6 days per week, at 5 gallons per visit, this would amount to 525 gallons per week, compared to a typical residence of 1,050 gallons per week (7 days x 150 gal. per day per residence). The assumption of 5 gal/visit is high,considering that all toilets are required to be low flow 1.6 gal/flush. For these reasons, in our opinion, the assumption equating the processing facility usage to %2 a normal household would be conservative. Although the total property encompasses approximately 38.5 acres, we would envision potentially a higher waste stream from the future wine tasting room and therefore, recommend that the a larger portion of the acreage be set aside for that second system. For the purposes of our computations, we have assumed that the processing facility would utilize approximately 5 acres of the site, therefore, "A (the number of dwelling units per acre on septic tanks)" would equal .5 dwelling units divided by 5 acres or .1. The selection of other parameters were based on previous studies by our firm, as well as a report dated March 19, 1997, by Questa Engineering Corporation and authored by Mr. Norm Hantzsche. Mr. Hantzsche prepared his report for a subdivision in north Stockton which had similar fine-grained silts and clay soils of very low permeability. For these reasons, we have chosen to use similar values considered appropriate by Mr. Hantzsche for this project. With a lack of washing facilities, which would normally dilute the nitrate concentration of the leach field affluent, we have used an NW value of 60 mg/L which is in the high range according to the Questa report. For "D" (Dentrification of leach field effluent) we have used a value of 0.25 versus a higher number commonly used for the more clayey sites. 20-4600-01/2011 L647 Page 3 of 5 Copyright 2001 Kleinfelder,Inc. October 2,2001