Water demands across the United States have grown steadily since 2000. New approaches must thus be developed to deliver and store safe, quality water. While dams and reservoirs offer two solutions, underground storage is another alternative generally considered to be quite safe. This system is not without its own problems, however, which include concerns with water quality and the potential for system leaks. Underground water tanks may also be questionable because of inconclusive regulations and costly installation.
Water Quality
Water quality is an ongoing issue of concern with many types of holding facilities. Underground water storage in particular poses the question of contamination. According to the National Academies of Science (http://dels-old.nas.edu/dels/), such contamination is dependent upon several factors, including the water's source and the chemicals used for water treatment. Urban storm water, for example, often varies considerably in terms of quality and may be more polluted than other water sources.
The National Academies of Science indicates a need to understand the contaminants that may exist in underground storage tank waters. Disinfection methods are often needed before the water is stored, and those methods in turn need to be monitored for the subsequent creation of byproducts. Chlorine is generally considered the best filtration method for underground water storage systems.
Leaks and Damage
Underground water tanks sometimes have to be replaced in major metropolitan areas. In Boston, Massachusetts, for example, three tanks used to store clean water were leaking thousands of gallons each day. This raised concerns about the structures themselves and the potential to damage mechanical equipment.
Upon inspection, the three tanks revealed a large number of "bugholes," deteriorated concrete and corroded reinforcement visible through the concrete. Professionals surmised such problems were the result of insufficient concrete coverage over reinforcing steel, inadequate interior waterproofing and lack of maintenance. A repair system was thus established in November 2007.
Inconsistent Application of Regulations
Regulatory policies are often used to ensure the safety and quality of water management systems. Inconsistencies exist, however, with regard to federal regulatory requirements for underground water storage. What ensues is inconsistent application of these policies depending upon local jurisdictions. Some areas, for example, attempt to manage surface water contamination by diverting polluted above-ground water into groundwater systems. This can, in turn, contaminate underground water and storage systems without appropriate controls.
Cost of Installation
According to the New Mexico Office of the State Engineer (www.ose.state.nm.us/), the biggest problem with underground water storage for most people is the cost of installation. These systems generally cost twice as much as above-ground systems. In part, the large costs are owed to excavation and backfill, both of which are required for installation of underground water tanks and supplies. For example, underground storage systems must usually have longer runs of pipe, conduit and electrical wire. Additional costs as incurred by machinery, skilled operators removing large quantities of earth must also be factored.
Costs may also be incurred if problems with the underground tanks occur. Most of the water system is buried, and thus accessing tank walls and other parts may be difficult. Skilled technicians are thus required in such instances. Although rare, cleaning an underground tank may also pose a significant challenge (Reference 3).
Tags: underground water storage, storage systems, underground storage, underground water, water storage, water tanks
