Goldfield Water System Arsenic Compliance Feasibility Study
BACKGROUND
Goldfield is located 30 miles south of Tonopah and 180 miles north of Las Vegas on US Highway 95. Goldfield began as a mining camp in May 1903 with a population of less than a dozen. It was producing $10,000 a day in gold by 1904, and by 1906 was a bigger city than Tonopah. It grew to around 20,000 as a result of several large ore discoveries.
At its peak of prosperity Goldfield was an eccentric combination of wild western boomtown and respectable city. Goldfield was the largest city in Nevada. The Goldfield Hotel was the most luxurious stopping place between Kansas City and the Pacific Coast. The community's boom was short-lived, and by 1910 the mines were in decline. Today, Goldfield is home to approximately 550 people.
The Goldfield water system was developed around 1903 using shallow wells. Ultimately, three private water companies brought water from outlying springs. In 1937, the County took over the private water system. In 1940, a rehabilitation program replaced 12,000 feet of pipe, provided adequate fire protection, electrified all pumps and cut off all unused sections of the distribution system. Between 1940 and 1980, while water was plentiful enough to serve the community, water quality at a number of the sources was poor. This required the operator to mix water from the various sources to meet the Bureau of Health Protection standards. Eventually, mixing of the water sources did not meet standards and a new water source was required. In the early 1980s, additional improvements were made to the system including: additional storage, 18,000 feet of 8-inch main added to the distribution system and two wells 12 miles north of Goldfield, one of which was connected to Goldfield with 6-inch pipe and two booster stations in series.
In 2000, most of the distribution system was replaced, a new water tank was constructed and new pumps installed in the wells and booster station with the help of an AB-198 grant.
PROJECT DESCRIPTION
The Esmeralda Board of County Commissioners applied for a grant under the AB 198 program to assist with an arsenic compliance feasibility study. The grant was approved by the Board for Financing Water Projects on August 4, 2005, for $29,750 (85% of the total eligible project cost of $35,000).
The source water for the Goldfield Utilities Public Water System has an arsenic concentration of 34 to 42 µg/L (ppb). Goldfield was out of compliance when the new arsenic regulations took effect January 23, 2006. In September 2006, the State Environmental Commission granted the Goldfield water system an exemption from the arsenic compliance requirement until January 23, 2009. The feasibility and a pilot study will provide a solution for Goldfield to meet the new arsenic regulations.
PROJECT STATUS
With further financial assistance from the US Department of Agriculture - Rural Development (USDA), the feasibility study was converted to a PER and completed in November 2007. Several options for arsenic compliance were investigated including: a new water source, blending, connection to other existing water systems, rehabilitating the existing water sources, and treatment. Of the options investigated, treatment appears to be the most economical solution at this time. Pilot testing of both adsorptive media and coagulation-filtration processes was conducted. The primary arsenic species in the Goldfield water is arsenate (As [V]) thereby eliminating the need to oxidize the arsenic prior to treatment. While adsorptive media was able to successfully remove the arsenic, competing ions (i.e., silica, potassium, vanadium, selenium, and chromium) caused a lower than expected bed life during the pilot testing. Lower bed life results in a lower volume of water treated prior to media regeneration and higher operating costs. The pilot tests conducted using a coagulation-filtration process showed a production efficiency of 97.8% and was a reliable treatment method for the Goldfield water sources. The coagulation-filtration media also has a manufacturer's guaranteed minimum life of 10 years. The coagulation-filtration process will require a backwash process and thus create a waste stream at the point of treatment.
The coagulation-filtration treatment system is planned to be constructed within the fenced perimeter of the two storage tanks. This area does not appear to be large enough for a lined drying pond for the sludge from the backwash; however, an area below the existing storage tank compound, currently owned by the County, should be large enough to accommodate the pond and could be made available to the water system.
The total project cost was estimated to be $1,123,624. Additional annual operation and maintenance expenses estimated to cover the treatment system total $25,125.
Esmeralda County submitted a pre-application project proposal to the Nevada Water and Wastewater Review Committee (NWWRC) in January 2008. Prior to the NWWRC process, Esmeralda County applied for and received grant funding from the Community Development Block Grant in the amount of $50,000 for engineering design of a treatment facility. Subsequent to the NWWRC process, Esmeralda County applied for loan and grant funding through the USDA-RD. In March 2008, the Board for Financing Water Projects voted to approve a Letter of Intent submitted to the AB-198 grant program. Esmeralda County did not submit a construction grant application to the AB-198 program.
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