2002-12-16_REVISION - M1977344 - Laserfiche WebLink

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(Sept. 11, 1998) and iron in the May 5, 2000 MW-8 groundwater sample, the iron and manganese standards were exceeded for every groundwater sample collected from MW-5, MW-7, MW-8, MW-9, and MW-10 (Table 4). Nitrate was elevated in the single groundwater sample collected from MW-6 (8.5 mg/L) but did not exceed the standard (10 mg/L). Ambient groundwater quality exceeded WQCC groundwater table values for several parameters including iron, sulfate, nitrate, aluminum, manganese, selenium, and thallium. These exceedances occurred in groundwater collected from the upgradient monitoring well as well as from monitoring wells completed downgradient of CKD disposal azeas. In general, the composition of groundwater in the Codell sandstone beneath the Site is similar to the composition of groundwater sampled from the upgradient monitoring well MW-6 completed in the Fort Hays limestone and may indicate that dissolution of minerals from the limestone is controlling the groundwater chemistry at the Site. The elevated levels of sulfate and iron found in all wells, including upgradient well MW-6, likely is caused by oxidation of disseminated pyrite found in the Fort Hays limestone. 3.2 Surface Water Quality Surface water samples were collected from the former Sand Pit (SP) area and Frog Pond (FP) between July 1991 and June 1994 (Figure 2) (Holnam, 2001). The former Sand Pit area was located on the bench above the quarry office (see location of SP-1 in Figure 2) and was used to provide sand for cement making purposes. The water that collected in this azea may have been a surface expression of groundwater from the Codell Sandstone. The former Sand Pit area was backfilled with overburden material sometime between 1999 and 2001. CKD was not disposed of in this area due to the concern for contact of CKD with the standing water. The Frog Pond is located in the quarry area outside of the Permit area. Samples were analyzed for TSS, ammonia, pH, and BOD (Table 3b). TSS ranged from 12 to 76 mg/L in Frog Pond samples and from 6 to 126 mg/L in Sand Pit samples. The pH ranged from 7.4 to 8.9 for Frog Pond samples and from 7.3 to 8.7 for Sand Pit samples. BOD was less than 5 mg/L for all Frog Pond and Sand Pit samples. One surface water sample (AR-1) was collected May 21, 2001 from the Arkansas River upstream from where the conveyor crosses the River (Table Sa) (K-S & Company, 2001). Detectable concentrations of barium, lead, aluminum, iron, and manganese were measured. Surface water quality data for sample AR-1 were compared with historic water quality data for three USGS water quality sampling stations on the Arkansas River (Table Sa) (USGS, 2002). The Arkansas River at Canon City station is located approximately 800 ft upstream from Sand Creek, the Arkansas River at Portland station is located at the State Highway 120 bridge at the Holcim plant, and the Arkansas River near Portland station is located 5.4 miles southeast of Portland. Concentrations of chloride, sulfate, fluoride, nitrate, potassium, sodium, iron, manganese, magnesium, and calcium increased along the Arkansas River in the down stream direction (Table Sa). Concentrations of detected constituents in AR-1 were of a similar magnitude to concentrations of detected constituents in the USGS Arkansas River samples. Surface water quality samples were collected from two locations on Bear Creek; BC-1 located just downstream from Highway 50 and BC-2 located just upstream from the confluence of Beaz Creek with the Arkansas River (RGI, 1999). Temperature, pH, and lead, 'von, and sulfate concentrations increased in the down stream direction from BC-1 to BC-2 (Table Sb). Total coliform and nitrate decreased between BC-1 and BC-2. BLASLAND, BOUCK & LEE, INC. rznsroz engineers 8 scientists 33 Groundwa~ahtonttoring Plan Il.dot