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South San Joaquin Irrigation District DRAFT Lead Assessment&Abatement Work Plan April 9, 2017 The approximate areas of the where lead pellets are found and the resulting impacts to water in the canal during growing season are summarized in the Table 1 below. Approximately 100 lead pellets/sq ft are present on the canal banks and road and 10 lead pellets/sq ft are on the canal bottom, Shot sizes for trap shooting include 7 1/2, 8, and 8 '/2. These sizes translate to a diameter of 0.095", 0.090", and 0.085", respectively. A shot size of 7 '/2 contains approximately 350 lead pellets/oz or 0.003 oz/pellet. A shot size of 7 '/2 was used to give the most conservative value of the maximum pellet weight. To assess the potential impact of lead pellets to canal water quality, the solubility of the lead was estimated by analysis of data from two shooting ranges in California found on the Department of Toxic Substances and Control's (DISC) Envirostor Database. Based on this data, lead solubility was estimated at approximately 58%. The amount of canal water passing the area impacted by lead pellets was estimated at 130,000 acre feet during irrigation season. The concentration of soluble lead in canal water was estimated by dividing the total soluble lead by the total volume of canal water. Table 1. Summary of Soluble Lead Impact to Canal Surfacewater Quality North Bank Canal South Bank Parameter + Road Bottom +Road Length (ft) 5.5E+02 5.5E+02 5.5E+02 Width (ft) 5.0E+01 5.0E+01 4.5E+01 Area (Sq Ft) 2.8E+04 2.8E+04 2.5E+04 No. of Pb pellets/Sq Ft 1.0E+02 1.0E+01 1.0E+02 Est. No. of Pb pellets 2.8E+06 2.8E+05 25E+06 Pb Pellet Wt (oz) 2.9E-03 2.9E-03 2.9E-03 Grams/oz 2.8E+01 2.8E+01 2.8E+01 Pellet Wt(g) 8.0E-02 8.0E-02 8.0E-02 Wt of Pb pellet in section (g) 2.2E+05 2.2E+04 2.0E+05 Wt of Pb pellet in section (mg) 2.2E+08 2.2E+07 2.0E+08 % Pb solubility 5.8E+01 5.8E+01 5.8E+01 Soluble Pb(mg) 1.3E+08 1.3E+07 1.1E+08 Vol. of water(acre feet) 1.3E+05 1.3E+05 1.3E+05 Acre foot/liter 8.1E-07 8.1E-07 8.1E-07 Vol of water(L) 1.6E+11 1.6E+11 1.6E+11 Conc.of soluble Pb in water(mg/L) 8.0E-04 8.0E-05 7.2E-04 Conc. of soluble Pb in water(µg/1) 0.796 0.080 0.716 Weighted Average (µg/1) 0.724 Page 8 Blankinship & Associates , Inc .