Preliminary assessment of environmentally-sound methods for treating and/or diverting rainwater run-off from parking lots and roads in the vicinity of Carlsbad Cavern : Draft report

Bremer, Mark

Currently there exists few storm water quality devices in any of the park's drainage systems. Existing accident mitigation procedures are inadequate for large spills and management policies related to storm water quality are required to reduce the level of pollutant generation. This study examined the pollutant sources that potentially contribute to the pollution detected in storm water run-off and examined various measures to mitigate the contamination problems specific to the pollution type encountered. Specific measures from diversion of run-off to adjacent watersheds to treatment methods are investigated. The effectiveness of each of these methods are evaluated with respect to: pollutant removal efficiencies; disturbance to impacted areas; associated benefits; and construction, maintenance, and engineering costs. Recommended accident mitigation procedures and management policies related to storm water quality are integrated with engineering measures for a comprehensive storm water management approach. This report demonstrates the need for significant improvements in existing infrastructure, accident mitigation procedures and management policies for the overall improvement of water quality on the surface and in the caves. These methods may permit some reduction of risk to cave resources for the long term, however they do not impact or change the type and control of land use, namely the use of parking areas and access roads for: visitors; operations and maintenance facilities; and residents. The methods presented in this report should be considered as short term mitigation and implemented only in the interim until the contaminating source areas are closed. The treatment measures recommended have the ability to remove a significant percentage of pollutants contained within the storm water run-off. However they are ineffectual at eliminating them. Cost and site constraints as well as the preservation of park esthetics limit the types and extent of measures which are feasible to address the problem.