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{ 13 November 1997 • AGE-NC Project No 95-0128 Page 3 of 5 The net effect of rising ground water elevation on the concentrations of TPH-g in ground water can be seen by comparing Figure 4 to Figure 5 These figures demonstrate that rising ground water elevation has caused a dramatic increase of TPH-g concentrations in ground water and a wider inferred extent of the resultant plume By analogy to the TPH-g concentrations, the concentrations of other fuel hydrocarbon compounds and additives have also increased in concentration and extent of areal distribution WELL SURVEY AGE has performed a survey of water wells within 4,000 feet of the Arco Mini-Mart property Five water wells were identified and located, generally southwest to southeast of the subject property, at distances ranging from 1,200 feet to 3,500 from the subject property Figure 6 - Well Survey shows the locations of the identified wells in relation to the site The initial ground water monitoring events at the property found ground water flowing toward the southeast, but the flow direction has shifted toward the northeast with the rise of ground water elevation The distances of these wells from the subject site makes it unlikely that the fuel hydrocarbons would impact them if the flow direction shifts again, although the same cannot be said with certainty for MTBE and the oxygenated volatile . compounds Even though these wells may not be impacted by the fuel hydrocarbons, the plume migrating off-site may cause some local restriction of potential use of the ground water, which is considered to be of beneficial use in this area Hydrocarbons entrained and dissolved in the ground water will also impact soil off site, extending the capillary fringe smear zone DISSOLVED IRON AND MAGNESIUM During the quarterly ground water monitoring event of October 1997, two ground water samples were analyzed for iron and magnesium content to check for site suitability for sparging Oxidation of iron may cause fouling of the sparge points The samples, MW4/10-30-97 and VW1/10-30-97, were found to contain 0 97 milligrams per liter (mg/1) and l 8 mg/I of dissolve iron, respectively, and 3 2 mg/1 and 4 9 mg/I magnesium The iron content is not anticipated to cause a significant fouling problem PHYSICOCHEMICAL AND MICROBIOLOGICAL ANALYSES Ground water samples MW4/10-30-97 and VW1/10-30-97 were also sent out for physicochemical and microbiological analyses to evaluate the natural conditions for natural attenuation of petroleum hydrocarbons in ground water through biological activity As detailed in a report to be prepared at a later time, the water was found to Iack sufficient ortho-phosphate and low to non-detectable . populations of selective biodegraders