Laserfiche WebLink
calcium bicarbonate type. Elevated concentrations of calcium and bicarbonate which <br />occur in the groundwater along all major water courses reflect the makeup of stormwater <br />runoff in the area —a major contributor to natural groundwater recharge. <br />The Environmental Protection Agency was given the responsibility of evaluating the <br />impacts to surface and groundwater quality resulting from the Rillito Recharge Project <br />and reporting those impacts to Congress as part of the annual reporting process <br />conducted by Reclamation. A memo from Mlay and Cook (1989) implemented the <br />groundwater protection policy developed by EPA specifically for the High Plains States <br />Groundwater Demonstration Program. The policy stated that no endangerment of <br />drinking water would occur if water injected did not exceed the National Primary <br />Drinking Water Standards for maximum contaminant levels or Health Advisory levels or, <br />if standards are already exceeded, no endangerment would occur if constituents in the <br />injectate did not exceed ambient concentrations in the groundwater. The Rillito Recharge <br />Project did not use direct injection, and recharged water passes through the soil, <br />undergoing soil aquifer treatment. <br />Water Quality Monitoring Program Methods <br />Water quality investigations began in fiscal year 1986 -87 with these objectives: <br />• Baseline characterization of the groundwater quality at the recharge site <br />A characterization of the quality of the recharge water sources <br />A program of monitoring focused on changes in groundwater quality at the <br />recharge site during operation <br />The U.S. Geological Survey collected water samples from 14 wells from August 25, 1986, <br />through March 28, 1989, and from 4 streamflow stations from March 25, 1987, through <br />March 13, 1992 (Tadayon, 1995). The 14 wells were located within a 2 -mile radius from <br />the confluence of Tanque Verde Creek and Pantano Wash downstream to Alvernon Way <br />(Smith and Tadayon, 1993). Before samples were collected, each monitoring well was <br />purged until a volume of water that equaled three casing volumes was removed <br />(Tadayon and Smith, 1994). Specific conductance, pH, and temperature were continually <br />monitored until stable (Tadayon and Smith, 1994). <br />From December 1992 through August 1993, USGS collected surface water samples at the <br />four sites listed above, and in September and May 1994, they collected surface water <br />samples from Tanque Verde Creek and Alamo Wash (Tadayon, 1995a). Groundwater <br />samples were collected from six monitoring wells in January and September 1993 and <br />from two wells in January, May, July, and October 1994. <br />Surface and groundwater were sampled in accordance with State and Federal regulatory <br />guidelines. Guidance documents include, but are not limited to: EPA Methods for <br />Chemical Analysis of Water and Wastes (USEPA- 600/4 -79 -020, March 1983), Water and <br />Wastes, EPA Methods for Virology Monitoring, Methods for the Determination of Organic <br />Compounds in Drinking Water (USEPA- 600/4 -88 -039, December 1988), Standard Methods <br />for Examination of Water and Waste -Water (APHA, AWWA, WPCF; 16th edition, 1985), <br />Program Summary Report Part /// — Demonstration Project Summary Reports 13 <br />