Water Table Survey of the I-66, 31W Interchange

A Report by Team 2.
The Purpose of this paper is to relate our findings on the hydraulic inventory investigation carried out for the construction of a water table map in the I-66, 31W interchange area of Bowling Green Kentucky. The boundaries of the area form a rough rectangle in the corner areas of the Bowling Green North, Bowling Green South, Polkville and Bristow quadrangles. The boundary runs from Plum Springs to Bristow in the north, then turns south following Bristow Rd to McGills Rd, down McGills Rd to Porter Road, and then South South West to the sharp bend in the Barren River. The southern boundary runs east to west along the river and then turns north with the Barren, crossing the bypass and forming a straight line to where Grahm Springs discharge enters the Barren. The loop is closed with an east turn towards Plum Springs.

Geology

The Geology within the boundary area is composed of Mississippian age limestones of the Ste Genevieve, and St Louis Formations, with Quaternary alluvial deposits in the river floodplain. The study area is bisected by the exposure boundary of the Ste Geneveive and St Louis. This boundary parallels I-66 from the east to the interchange, the interchange connector, and 31W to the west of the interchange. To the north of this boundary is the Ste Genevieve Limestone, an oolitic limestone, intersected by several chert layers which act as confining layers, giving a surface topology of wide shallow sinkholes. To the south is the St Louis formation, a multi component formation with a argillaceous sparite limestone forming its upper member, and a shale and argillaceous limestone lower member which serves as the base level for the area. The St Louis is identifiable topographically by its deep narrow sinkholes. The area of study is extremely Karstified with only the base level Barren River flowing on the surface.

Hydraulic Inventory

During the conducting of the hydraulic inventory, we examined the area for water wells, karst windows, blue holes, springs and caves. The water well component is usually the most readily available source of water table data. Unfortunately, the region of study has been connected to "city water" (from Bowling Green) for the last 20 years, and before that connection, the majority of the houses ran off of cisterns filled by the capture of rain water from the resident's roofs. We were able to find 4 water wells that could be measured (Water wells 1-4 on the map). Unfortunately, the pumping mechanisms sealed the shaft so we could not measure them without disassembling the pump. We have marked these locations on the map so wells can be accessed in an emergency.

There were no karst windows found in the area of study. There were three blue holes located and a total of three springs. (Five counting Grahm spring and the Water Works spring, but these were just outside the study area.) These were the major source of water information in the study area and are listed on the map.

Finally, there are two caves we are aware of in the study area. Neither were said to have water running in them so they were not included on the map.

Results

Due to a lack of data points, it was impossible for a water table map of any reasonable accuracy to be developed for our study area. We were able to come to the following conclusions based on the data available.

The area of study is composed of two aquifers, one in the Ste Genevieve Limestone and one in the St Louis. The aquifers are separated by a chert confining layer and mix at the boundary of the St Louis and St Geneveive. The evidence for this data is found in the elevations of the three springs of the region. The lowest value is in spring 2 and the nearby blue holes. These are located in the bottom of a solution valley that is forming at a breach of the chert at the border of the St Louis and Ste Geneveive near Jackson Grove Church on the Bristow quadrangle. The next highest value is spring three, which is located right under the chert layer as evidenced by a cherty roof of the spring sinkhole and a similar sinkhole nearby. This is probably leakage from the Ste Genevieve aquifer to the St Louis aquifer. The highest location is spring one. This spring is located at an elevation of 530 feet. A half a mile away is a blue hole at 450 feet and Grahm spring which is approximately 405 feet. Grahm Spring is known to drain a large basin that extends nearly to Smiths Grove, several miles away. It and its parent caves are located in the St Louis formation, under the confining chert layer. Spring one lies along the route of Grahm spring's recharge basin, and the former's elevation would form a hump in the water table inconsistent with the known flow route of Grahm spring's water. Based on this evidence, we conclude spring one is perched on the Ste Genevieve chert confining layer and is recharged from a perched aquifer.

Flow directions of the area of study are inconclusive with the data available from this project. the water from spring one probably exits through Grahm spring although surface topology indicates it may flow to Blue Hole one. The spring two/blue hole 2 and 3 area could drain in 2 directions. Along the solution valley between Bristow and the Bristow Rd overpass to join Grahm spring, or directly south from the blue holes along a lineament that joins the abandoned meander of the Barren river. Spring three's waters are unpredictable without further data.

Recommendations

In order to make a valid water table map there simply need to be more elevation points along the center of the study area. Measurement of the monitoring wells of the Corvette plant and in the North Industrial Park would be a definite improvement for the hydraulic picture as well as a dye trace from the springs or strategic sinkholes in the gray areas. A dye trace in the sinkhole just to the west of the I-66 off ramp would also be advised. In conclusion, more data needs to be gathered before any semblance of a useful map can be attempted.
There is a large map that was constructed to go along with this paper. Unfortunately due to size/memory constraints and the fact that it is in another state, this map is not avainiable for web posting.
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