Union Mine Landfill and Liquid Waste Treatment Facility

Union Mine Landfill Liquid Waste Treatment Facility

The Union Mine Landfill has been operated by El Dorado County since 1962. The facility ceased operating as a public disposal facility in 1996.

Please note: The landfill continues to be closed to the public.

Disposal Site and Waste Water Treatment Plant

The original portion of the landfill has undergone final closure. The remaining active area receives only sludge cake from the on-site wastewater treatment plant. The wastewater treatment plant currently processes septic tank waste (septage), portable toilet waste and liquid waste from the landfill (leachate). The landfill has three leachate collection systems and the landfill gas collection system. The landfill gas is incinerated in a flare and microturbines are used to produce power for the wastewater treatment plant.

Historical References and History

El Dorado County Landfill History

Until approximately 1973, there were at least 21 known small dumps (now called landfills) throughout the County. Most were unattended burn dumps where a person or entity could burn their trash and garbage. There were one or more burn dumps in Camino, El Dorado, Lotus, El Dorado Hills, Finnon Lake, Fresh Pond, Garden Valley, Georgetown, Greenwood, Kyburz, Meeks Bay, Meyers, Omo Ranch, Outingdale, Park Creek, Pilot Hill, Placerville, Silver Lake, Somerset and Wrights Lake. Because of air pollution control laws, capacity problems and varying neighborhood opposition, by 1975, all but the Union Mine Landfill were ordered closed.

Some of the former publicly owned landfills have now been discovered to have subsurface contamination. For example, vinyl chloride in concentrations 100 times the drinking water standard has been recently found in groundwater under the Meyer's Landfill which has been closed since 1971. An on-going site investigation and cleanup has been ordered. To date, the U.S. Forest Service, County and City of South Lake Tahoe have spent over $600,000 investigating this site. The cleanup and monitoring process for this site will require an additional expenditure of several million dollars.

Landfills in the 1990's

In the past and in a more rural environment "any old canyon" or the "back 40" would suffice for a dump and the cost of disposal was essentially "free". A barrage of new laws, generated both at the Federal and State level, have now been passed which dictate how all landfills are sited, constructed, operated, closed and monitored even after closure. Obviously, previous generations cannot be assessed and these recent mandates are now paid for by current residents.

New landfills or expansions to existing landfills must have a clay and plastic underliner and a mechanism to collect and treat "leachate", i.e. rainfall or groundwater which becomes polluted after leaching through garbage. Closed landfills must be retrofitted with a four (4) foot soil, clay and synthetic impervious "cap" and incorporate landfill gas control measures. A subsurface soils and groundwater study is required for many of the 21 known closed sites.

Operating landfills must also implement programs to monitor potential groundwater contamination. For example, the County's Union Mine landfill has installed 18 groundwater monitoring wells around the site which must be tested periodically for potential contamination. Run-off around and adjacent to the Union Mine landfill including Martinez Creek is also monitored and tested periodically for chemical contamination and biological and fisheries impact. The current annual cost to conduct the Union Mine water monitoring program is approx. $150,000/yr.

The groundwater monitoring program at Union Mine is exceptionally complex because of the approx. 20,000 ft. of mine shafts dug during the 1800's under and adjacent to the landfill site--the Union Mine area was historically one of the more active gold mine sites in the County. The mine workings about the Union Mine property have historically discharged mine wastewater which contains naturally occurring arsenic from the arsenic pyrite within the gold bearing quartz. The County has recently "plugged" the on-site mines to reduce and stop the uncontrolled discharges of groundwater passing through the mine openings.

Union Mine Status

The Union Mine Disposal Site, comprised of 280 acres of public property, is the last remaining and active landfill property in the County. The existing permitted landfill unit is confined to 59.5 acres within the middle of the Union Mine property [a number of permits are required to operate a landfill including those from the State Integrated Waste Management, Regional Water Quality Control and Air Resources Boards]. In 1996, at a cost of $1.3 million dollars, the County opened and completed the first of six phases of landfill expansion at Union Mine.

However, during June of 1998, Waste Management, Inc. acquired the Lockwood Landfill near Reno, Nevada as well as El Dorado Disposal Co., Inc. and Western El Dorado Recovery Systems, Inc. of Diamond Springs. As a condition of purchase and as ordered by the Board of Supervisors, Waste Management, Inc., a multi-billion dollar corporation headquartered in Houston, Texas, agreed to wholly indemnify and financially protect the County from future claims of pollution. This indemnification provides crucial financial protection for the citizens of the County by defraying any future pollution liability to Waste Management, Inc. Such a contractual arrangement would have prevented El Dorado County's financial exposure to the Meyer's and Union Mine Landfill liability.

Church Mine & Mining in area(PDF, 3MB) - book excerpts

Liquid Waste Haulers

The Union Mine Wastewater Treatment Facility is operated Monday-Friday from 08:00 AM to 5:00 PM and is available to be open during emergency situations with prior approval. Liquid waste haulers are expected to arrive at the facility no later than 4:30 PM to allow time for off-load and daily equipment shut down.

The facility is currently permitted to accept up to 16,000 gallons per day on a monthly average of liquid waste. Waste that is accepted at the facility includes solid mixtures pumped from septic tanks and portable toilets. The acceptance of restaurant, grease trap, car wash pumpings, commercial waste, Industrial waste and waste classified as “hazardous” as defined in Sections 2521 (a) of Title 23, CCR, Section 2510, et seq., (hereafter Chapter 15), or “designated” as defined in Section 13173 of the California Water Code, is prohibited.

Gun Range

A public shooting range is located adjacent to the landfill. In 2001, the shooting range's current operations were assessed for the environmental impact of lead, copper, nickel, and zinc - four metals associated with bullets and shell casings.

The El Dorado Rod and Gun Club charges fees and schedules the use of the site: (530) 672-3330.

Renewable Energy

In 2002, the Union Mine Landfill site was evaluated for alternative energy (wind and solar power) to effectively operate its existing systems.

Location and Information

Union Mine News


The Union Mine Treatment Facility is located at:
5700 Union Mine Rd
El Dorado, CA 95623
(530) 295-0429

Please Note: This facility is closed to the public!

These directions are provided primarily for deliveries and contractors/consultants performing work at the site.

  1. From Highway 50 Eastbound, exit at Missouri Flat Road/Diamond Springs offramp.
  2. Turn right (south) at stop light.
  3. Continue to Pleasant Valley Road ("T" in the road) - Turn right (west) onto Pleasant Valley Road.
  4. Continue to Highway 49 in the town of El Dorado - Turn left (south) onto Highway 49
  5. Turn left onto Union Mine Road - Continue for approximately 3 miles.

Map Union Mine location