the soil aluminum. Field observations indicate that several stressed areas show signs of recovery, particularly at the In May 1992 the Environmental Sciences Section (ESS) H-Area seepline. surveyed the Four Mile Creek seepline down gradient from the F-and H-Area seepage basins for tritium, specific conductivity, and pH. The survey was the first of four

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The EnvironmentalSciences Section (ESS) establisheda quarterlymonitoringprogramof the Four Mile Creekseepline clowngradientfrom the F-and H-Areaseepage basins. The programsurveys andtrackschangesin tritium, specificconductivity, and pH for the seepline water.Measurementsfrom the fourthquartersurvey (March/April1993) showed lower tritium andconductivity measurementsand higher pH values (pH 5-6) thanmeasurementsfrom previous studies. The resultsof the first four quart_ly surveys suggestthatinfiltnaionof rainfallmay be dilutingand flushingthe contaminants fromthe groundwatersystem. Mine measurementsareneeded to confmnthese trends. Executive Summary todischargeeffluentfrom F-Area separationspriorto the construction of the engineered effluent canal. Tritium In March/April1993 the EnvironmentalSciences Section activities rangedfrom37 to 682 pCi/ml on the east side of (ESS) surveyed the FourMile CreekseepHnedown gradi-the drainage and from 29 to 44,000 pCi/ml on the west ent from the F-and H-Area seepage basins for tritium, side. The tritium concentrationmeasuredin the streamof specific conductivity,and pH. The survey was the fourth the naturaldrainagewas 12,000 pCi/ml. Results suggest of eightquarterlysurveys for monitoringthemovementof that the tritiumoutcroparea has been encapsulatedby the contaminantsfrom the basins since closure.Surface-water sampling locations established on the west side of the samples were collected from 60 locations along the drainage. Conductivity and pH measurements taken on seepline; Haselow et al. (1990) sampled 44 of the loca-both sides of the drainage were similar and were within rims, 16 were on the seepline south of 643-E, which is a the range of normalvalues for the area. The low conduc-decommi&_oaedarea in lhe Solid WasteDisposal Facility. tivity valuesmeasuredalong the drainageway suggest that Samples were collected from3 locations along FourMile the tritium plume outcropping in the area emanates from Creek. Ot3-E since wastes introducedinto 643-E contained low levels of salt ions compared to the waste in the F-andH-Results Indicate thatrainfall may be diluting the contami-,Meabasins. pantplume thatleachedfromthe seepagebasins and flushing theconumfinantplume out of the shallow groundwater The results suggest that contaminant concentrations are in the wetland systems below the basins. ESS found Iri-decreasingat the F-and H-Areaseeplines and are consistium activities in theF-and H-Areaseeplines significantly tent with results fromprevious quarters(Dixon and Roglower than the activities measured by Haselow et al. ers, 1992; Dixon and Rogers 1993a and b). Areas of (1990). Conductivity measurements exhibited the same stressed vegetationare showing signs of recovery as contrendsas tritium activities in bothareas,indicatingthatsalt taminant concentrationsdecrease and pH increases. Aluions are also being removed from the wetland system, minum concentrations measured along the seepline in Concenlrationsof hydrogen ions also decreased in both 1989 OIaselow et al., 1990) were high enoughto be ...