The NSS Bulletin - ISSN 1090-6924
Volume 38 Number 2: 27-36 - April 1976

A publication of the National Speleological Society

Potential Gas Accumulation in Caves in Bowling Green, Including Relationship to Water Quality
L.P. Elliott


Although surface air and water pollution have attracted considerable attention, little research has been done in subterranean areas. The accumulation of methane and other gases in caverns may be related to the degrees of pollution of the cave water. This project proposed to determine: (1) the extent to which methane gas accumulates in the cave system under Bowling Green, and (2) the influence of water water pollution upon methane gas production.

To accomplish these objectives, it was necessary to monitor the physical, chemical, and biological characteristics of the cave water, as well as to analyze the cave air for gases. The tests included those for turbidity, apparent color, temperature, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total organic carbon, pH, coliforms, fecal coliforms, methanogenic bacteria, carbon dioxide, alkalinity, hardness, total residue, chlorides, sulfates, phosphates, nitrates, iron, and maganese; gases monitored included ammonium, carbon monoxide, hydrogen sulfide and methane.

This study of seven caves extended over a period of three months during the summer of 1973 and included the following caves: State Trooper, Lost River, Big Bertha, Livingstone, Lampkin (collectively known as the Lost River Complex), Field's and X Cave (Hunts).

The average turbidity in cave waters was 31 JTU's. The water in the caves had an average apparent color of 20 APHA color units. Average water tempterature in the Lost River Cave complex was 15.1°C (with slight fluctuations). Average water temperature for Field's Cave was 18.7°C and for Hunts was 18.1°C. Average cave air temperature for the Lost River Comples was 15.7°C. Cave air temperature in Field's averaged 17.8°C and in Hunts, 19.1°C.

A definite sewage odor was detected at sampling points B of Lost River and Big Bertha. A paint thinner smell in both water and air was detected at point B in Big Bertha. Automobile exhaust funes and gasoline odors were detected in Hunts.

The dissolved oxygen concentrations of the Lost River Cave complex averaged 8 mg/l, excluding sampling points B of Lost RIver and Big Bertha. Hunts Cave averaged 4.9 mg/l and Field's Cave 4.4 mg/l, dissolved oxygen.

Five day (20°C) BOD concentrations for seven of the 10 sampling sites averaged under 1.0 mg/l. Concentrations at site B in Big Bertha fluctuated in value from 0.16 mg/l to 105.4 mg/l, indicating an inconsistent discharge of waste into the water. The chemical oxygen demand at Big Bertha averaged 89.76 mg/l, whereas the rest of the sampling sites never had values greater than 50 mg/l.

The total organic carbon value for the Lost River Cave coplex water was 19.91 ppm. The water of Field's had an average value of 21.76 and of Hunts, 23.84 ppm. The drinking water of Bowling Green had an average value of 10 ppm.

The average CO2 value for the cave water of the Lost River complex was 37.3 mg/l, that of Field's was 34.4 mg/l, and that of Hunts was 44.3 mg/l. The water in all seven caves had hardness values between 150 mg/l to 300 mg/l

The total residue in all of the cave waters (except Lampkin) exceeded the Federal Drinking Water Standards (not more than 200 mg/l). Chlorides in the cave waters averaged 7.5 mg/l, sulfate concentrations averaged 15.9 mg/l.

The total phosphate concentrations in the cave waters averaged 0.48 mg/l. Nitrates averaged 6.9 mg/l. Both nitrate and phosphate concentrations were in ranges which would contribute to eutrophication.

The iron concentration in the cave waters averaged 0.41 mg/l. The manganese concentrations in the cave waters averaged 0.13 mg/l. No cave air contrained ammonia or hydrogen sulfide, but air in Hunts contained carbon monoxide. Mehtane was detected in all cave air samples, but not in high concentrates. When concentrations of methane found in caves were compared to those of surface air samples (control), statistically significant concentrations were found at site B in Lost River, in Big Bertha, and in Hunts.

The coliform count for waters (excluding Kampkin) averaged 18,690/100 ml, while fecal coliform counts averaged 4,144/100 ml. All cave waters enriched for Methanobacterium were positive, except on three occasions. Only seven enrichment cultures for Methanococcus-like organisms were positive.

Since the cave waters studies were considered polluted, the Federal Water Pollution Control Administration and the Kentucky Water Control Commission should pass effective regulations to keep the water from being further polluted. The city of Bowling Green should determine who is dumping and littering in the caves and prosecute those responsible. Where sewage and industrial pollutants are found entering the caves, an attempt should be made to determine where these originate and prosecute the offenders. Sufficient data has been gathered on the cave water to establish a baseline for water quality during summer months, but the water quality measurements should be continued to determine the effect of winter flow on the physical, chemical and biological qualities of the water, plus the changes that might occur in the cave air.

An experimental digester which simulates cavern conditions should be designed to determine if methane could build up to concentrations that might be explosive. In the future, methane organism in the cave water should be quantified. A study of the methane concentration in cave air would be faciliated by a portable gas chromatograph that could be taken into the caves. Since Warren County has abundant sinkholes and old gas wells which could be giving off methane, parking lots should be properly ventilated for the release of gas, particularly. All residents of the city who use flush toilets should be forced to connect to the sewer system that is available.

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