Hydrogeologic assessment of three solid waste disposal sites in the Brazos River alluvial deposits.

The Brazos River alluvial aquifer, which is composed of floodplain and terrace deposits, is a major source of shallow groundwater for the Brazos valley in central and southeast Texas. The alluvial deposits range from 10 to 40 feet in thickness and are composed of clayey and silty sands and gravel. The study area is located southeast of Waco, Texas, and west of the Brazos River. Here numerous gravel pits supplying resources to the city have later been incorporated as solid waste disposal sites. The solid waste disposal methods have changed over a period of years from dumps and unlined landfills to clay lined landfills. The presence of the solid waste disposal sites creates a pollution potential for the shallow aquifer. Therefore, an assessment of the pollution in three sites representative of three different disposal methods was undertaken. The investigation, which took place from July 1986 through January 1987, incorporated periodic water level measurements and four chemical sampling periods of 21 monitor wells which were installed up-gradient and downgradient of the sites. Where available, household wells and surface water bodies were also incorporated in the study. Groundwater flow is toward the Brazos River which acts as the discharge point for the alluvial aquifer. The water table ranges from five feet below the ground surface in the first terrace to 25 feet below the ground near the Brazos River. Within 2200 feet of the Brazos River, water table fluctuations are closely tied to changes in river level. Fluctuations in the upper floodplain and terraces are predominantly controlled by aerial recharge. Chemical analyses indicate that the ionic composition of the groundwater in the alluvial aquifer is highly variable over short distances. Groundwater chemistry varied at the three disposal sites in relation to groundwater flow. Up-gradient wells exhibited a calcium bicarbonate chemistry. Down-gradient wells showed no distinct ionic composition. Statistical analysis of the chemical data determined TDS, specific conductance, sulfate, chloride, and sodium to be the best indicators of contamination. All three sites showed similar contamination trends. At one site a contaminant plume was delineated downgradient of the landfill. Further studies incorporating the use of vertical well nests will be necessary if the dimensions of the plume are to be quantified.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Masters

Grantor

Baylor University.

Year dc:date.issued

1987

Author dc:creator

• Pinkus, Joel R.

Advisor dc:contributor.advisor

• Yelderman, Joe C.

• Sanitary landfills -- Leaching -- Texas -- Waco.
• Groundwater -- Pollution -- Texas -- Waco.
• Brazos River (Tex.)

Statement dc:rights

• Baylor University works are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. Contact libraryquestions@baylor.edu for inquiries about permission.

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/2104/14066

OAI identifier oai:identifier

oai:baylor-ir.tdl.org:2104/14066