Las Vegas Valley Water District - Town of Searchlight Arsenic Mitigation & Distribution System Improvements
BACKGROUND
The Town of Searchlight is located in Clark County, approximately 60 miles south of Las Vegas. On February 16, 1988, the Las Vegas Valley Water District (LVVWD) became responsible for the operation, maintenance, and administration of the Searchlight Water System through an Interlocal Agreement with Clark County. The LVVWD assumed full ownership of the system in 2002.
 The Town traces its roots back to the discovery of gold ore in 1897. This initial discovery led to the development of several mines in the area and caused the creation of the Searchlight Mining District in 1898. Searchlight began to boom in 1902 and in the early 1900s the town had a population of over 1,500, exceeding the population of Las Vegas at the time. By 1940, nearly $4.5 million in gold had been produced in the area. However, as gold and silver production costs increased and the grade of ore went down, people began leaving. By 1927, only 50 people remained in Searchlight. Today, Searchlight remains a small community with a population of approximately 760 residents. Nearly half of the population is retired while the remaining are miners, ranchers, and small business owners.
The Town is within the Piute Valley Hydrologic Basin. The LVVWD has existing permitted water rights totaling 4,353.95 acre-feet per year in the Piute Valley and the adjacent Eldorado Valley Basin. Currently, water is supplied by two groundwater wells. Well S-2 was drilled in 1990 and is the primary production well producing approximately 300 gpm. Well S-1 was drilled in 1983. It currently serves as an emergency backup well and produces approximately 150 gpm for short periods of time but is not a reliable supply. When wells are the sole source of water for a system and are in a remote area, redundant well capacity is required per Nevada Administrative Code. The water table and groundwater production rate at Well S-2 have declined steadily due to routine wear on the well. Recent maintenance of Well S-2 has indicated that the casing must be repaired or replaced. Rehabilitation of the casing on Well S-2 may be possible but would be a risk to the water system capacity without a reliable back-up well.
Storage for the Searchlight system currently consists of two storage tanks with a total capacity of 416,000 gallons.
In addition to infrastructure needs, Searchlight may be required to install treatment facilities to treat arsenic under the EPA Safe Drinking Water Act Revised Arsenic Rule. In September 2006, the State Environmental Commission granted the LVVWD an arsenic exemption for the water system in Searchlight until January 23, 2009. Based on the most recent arsenic analyses, Well S-2, at 8 - 12 parts per billion (ppb) arsenic, may not comply with the new arsenic standard of 10 ppb. Well S-1 appears to comply with the new arsenic standard. District operating funds were used to complete an arsenic treatment pilot study to determine the most cost effective arsenic treatment technology suitable for the area's groundwater chemistry.
PROJECT DESCRIPTION
The new well is anticipated to be in an area further west of Well S-2. In May 2005, the District advanced approximately $75,000 to the Searchlight Water System and completed a geophysical survey to facilitate the groundwater study to identify possible well sites for a new replacement well. As a result, six locations were identified as having high potential to yield a safe reliable water supply and being potential sites for drilling four exploratory wells for further characterization. The best site will be selected for construction of a new replacement production well. While groundwater exploration is prudent, state regulations do not have a requirement on the number of test wells that need to be explored. The most cost efficient approach to the project would be to drill one exploration well and determine if it meets the water quality and quantity needs prior to exploring other well sites. The exploratory drilling is part of a larger project that will ultimately result in two new production wells for Searchlight and several valley monitoring wells.
The Las Vegas Valley Water District applied for a grant for the Town of Searchlight under the AB-198 program to assist with the costs of a new production well and appurtenances. The grant was approved by the Board for Financing Water Projects on August 23, 2006, for an amount not exceed $2,536,522.34 (approximately 78.5% of eligible project costs estimated to be $3,231,238.65).
PROJECT STATUS
In the fall of 2007, four exploratory wells were drilled each to a depth of 1,000 feet. The water quantity and quality was tested for each well to determine the best wells to convert to production wells. Currently the LVVWD is working through the BLM's environmenal assessment process. The location of the wells is in an area of critical environmental concern as it is desert tortoise habitat.
|
