Date of Award

Summer 8-1990

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Geology

Committee Director

G. Richard Whittecar

Committee Member

Joseph H. Rule

Committee Member

Eugene A. Siudyla

Call Number for Print

Special Collections LD4331.G4D37

Abstract

In 1986 the City of Chesapeake, Virginia began to dig shallow ponds ("lagoons") to contain alum sludge, a waste generated by the City from the process of treating potable water. Borings at the disposal site reveal that the near-surface geologic units include a thin mud-rich facies which overlies a thick sandy facies, both of which are in the Lynnhaven Member of the Tabb Formation. At 7 meters depth, a clay-rich facies of the Yorktown Formation (Morgarts Beach Member?) underlies the sandy water table aquifer. Water levels from twenty observation wells and two monitoring wells installed into the water table aquifer were measured from 22 May 1987 to 8 February 1988. Analyses of data from a twenty-one hour pumping test conducted on the water table aquifer indicate an average transmissivity of 38.2 m2/day and an average hydraulic conductivity of 7.3 m/day. The distribution and variation over time of measured heads suggest groundwater flows northeast approximately 3 to 4 cm/day (9 to 16 m/yr) beneath the study site. Thus groundwater from beneath the eastern-most lagoon will take approximately 38 to 68 years to reach and discharge into Indian Creek.

Analyses for dissolved aluminum, calcium, potassium, sodium, sulfate, chloride, and pH in water samples collected from two lagoons and one well demonstrate that sulfate exists in greater concentrations in the lagoon leachate than in the ambient groundwater. Leachate generated with the batch extract method from a sample of alum sludge contained (in decreasing order of concentration) sulfate, calcium, chloride, sodium, potassium, and aluminum. Soil sorption experiments reveal that sediments at the site have a high adsorptive capacity for the concentrations of these ions found in the waste lagoons. Calcium was most readily adsorbed followed by sulfate, sodium, and potassium. Chloride did not adsorb to the sediments

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DOI

10.25777/qzxn-y782

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