Clark County is responsible for making sure that water bodies affected by activities of residents and businesses within the Las Vegas Valley, are pollution free. Sample tests of run-off water taken regularly in the Las Vegas Wash outlet, too often, result in high levels of bacterial content that exceed safe water contact recreation, especially during rainy weather. One potential source of bacteria in the watershed is malfunctioning sewage disposal systems. Septic tank failures have been documented on private properties in the Las Vegas area. The following information is a reminder on how to maintain a private sewage disposal system --and keep our environment clean. Septic System Description A septic tank is the first stage of a private sewage disposal system. The septic tank is a watertight tank below ground and is usually made of concrete and sometimes of fiberglass or steel. It usually has one or two access ports a few inches below ground. The tank receives household wastewater through an inlet pipe near the top of one side, settles out larger material to the bottom, breaks down waste material with in situ bacteria, and delivers the partially treated wastewater out another pipe on the other side to the disposal field via a distribution box. A disposal field is the second stage of the private sewage disposal system and completes the final breakdown of the wastewater with organisms in the soil. The disposal field consists of narrow trenches filled with gravel and perforated pipes that distribute the wastewater to the field. With proper maintenance, a well designed system should last indefinitely; however, disposal field soils will normally clog if forced to handle the large particles that should settle out in the bottom of the septic tank. Routine pumping of the septic tank is imperative to avoid thousands of dollars in replacement costs of the disposal field.
Eliminating phosphate containing detergent can reduce phosphorus loads to septic systems by 40 to 50 percent. Certain soil conditions combined with close proximity to sensitive surface waters can result in increased phosphorus pollutant loading in the stormwater.
Organic solvents are advertised for use as septic system cleaners and sometimes as substitutes for sludge pumping, however there is little evidence that such cleaners perform any of the advertised functions and can instead exterminate useful microbes, resulting in increased discharge of pollutants.
In addition, the chemicals themselves, halogenated and aromatic hydrocarbons, can easily contaminate storm waters and some common cleaner constituents are listed as environmental pollutants. Restrictions on the use of these additives can preclude further exacerbation of poor system function.
Eliminating the use of garbage disposals can significantly reduce the loading of suspended solids, nutrients, and BOD to septic systems, as well as decreasing the buildup of solids in septic tanks, thus reducing pumping frequency.
Septic tanks require regular inspection and maintenance. Pumping should be done to remove accumulating sludge approximately every 3 to 5 years. The frequency can vary depending on tank size, family size and garbage disposal use. Failure to remove sludge periodically will result in reduced tank settling capacity and eventual overloading of the soil absorption system, which is more expensive to remedy. Maintenance can be required through contracts, operating permits, and local ordinances/utility management.