SU0011266 SSNL - Laserfiche WebLink

Home Browse Search

Nitrate Loading Study- Update 2 1��rracon Macchia Winery Acampo, CA February 6, 2017 Terracon Project No. NA177004 The site's new total average daily flow is 254.90 gallons per day. The average total nitrogen concentration of domestic waste water is normally considered to be 20-85 mg/L-N with 35 to 45 mg/L-N being typical (Crites and Tchobanoglous, 1998). The prior report indicated the commercial use will have higher concentrations of total nitrogen when compared to residential use due to lack of shower/bath and kitchen use, consequently an estimated total nitrogen of approximately 80 mg/L-N was used. Nitrate Loading A new nitrate loading scenario was performed to determine the impact from the reported existing and anticipated uses. The scenario utilizes the variables discussed previously which represent the estimated conditions and uses associated with this project. The following table presents a summary of the nitrate loading calculation for the parcel and includes results from the original 2007 report and update letter. Table 3. Summary of Nitrate Mass Balance Analysis. Result Average Effluent Leachfield Deep Daily Concentration Denitrification Percolation Year Parcel (Nc)* Acres Flow(Q) (Nw) (d) of Rainfall (mg/L- (A) (Table 1) (mg/L-N) (R) (in.) N) (gpd) 2007 1 5.4 1.50 126.00 80.00 25% 14.06 2017 1 9.25 1.50 254.90 80.00 25% 14.06 ' Maximum contaminant level(MCL)for nitrate in drinking water is 10 mg1L-N. Based on the nitrate mass balance calculation, nitrate levels for the reported current use and proposed land use is 9.25 mg/L N which is below the USEPA maximum contaminant level (MCL) of 10 mg/L-N. Groundwater Sample Two groundwater samples (W1 and W2)were collected from the on-site groundwater well by Ms. Tamara Woods of our office on January 26, 2017. Groundwater samples were collected at the exterior faucet located on the northeastern corner of the craft house. Mr. McMahon was asked by us to run the faucet for approximately 5 minutes in order to purge the system. He indicated, that the faucet had been running for 6 minutes prior to us sampling. Evidence of the purge (standing water)was observed by Terracon upon sampling. Groundwater samples were analyzed for nitrate and DBCP by McCampbell Analytical, Inc. For the groundwater sample, Nitrate was reported at 7.4 milligrams per liter (mg/L-NO3) which is below the maximum contaminant level (MCL)of 45 mg/L-NO3. DBCP was not encountered in the groundwater sample. Conclusions Based on a review of the nitrate loading results, estimated nitrate levels for the current and proposed land use is 9.25 mg/L N below the maximum contaminant level (MCL) of 10 mg/L-N. Groundwater samples collected from the on-site groundwater well reported below MCLs for nitrate and below laboratory detection limits for DBCP. We understand that bathrooms at the tasting Resourceful a Reliable ® Responsive 3