| ADEC | State of Alaska Department of Environmental Conservation |
| 555 Cordova Street Anchorage AK, 99501 (907) 269-7647 Web site: http://www.dec.state.ak.us/index.htm |
| Alternator Valve | A valve used to alternate the flow of wastewater between the primary site drainfield and the reserve site drainfield. |
| Bed | A drainfield that has a shallow excavation wider than five feet containing 6 inches of sewer drainrock below the perforated distribution lines. A bed type system is designed for bottom absorption only. |
| Biomat | Biomat is a biological growth that over time prevents wastewater from absorbing past the walls of the drainfield. For more information, refer to the biomat section on the Failed Septic System? page. |
| CAD Technician | A person that utilizes Computer-Aided Design software to create precision drawings. |
| Class "B" Well | A public water system that is not a Class "A" public water system, and that regularly serves at least 25 individuals each day for at least 60 days of the year. (200' protective radius). |
| Class "C" Well | A public water system that is not a Class "A" public water system, a Class "B" public water system, or a private water system. (150' protective radius). |
| Cleanout | A 4 inch pipe that connects to the distribution line in a drainfield that allows for "snaking" or jet cleaning of the distribution line. Cleanouts must extend above the ground surface for access and maintenance. For a diagram, see cleanouts and monitoring tubes. |
| Conventional Septic System | The most commonly installed septic system that consists of a septic tank with or without a lift station followed by a drainfield. For more information, go to the conventional septic systems page. |
| COSA | Certificate of On-site Systems Approval: Formally known as an HAA, the COSA is a certificate issued by the MOA which serves as confirmation to lending institutions that the well and/or septic system, serving a single family residence, have been inspected by a professional engineer and have been found to be in compliance with the applicable standards. |
| Deep Trench | A drainfield that is 12 to 36 inches wide and contains at least 4 feet of sewer drainrock below the horizontal perforated distribution line. A deep trench type system uses side-wall distribution only. |
| Distribution Line | A perforated pipe(s), often called drainpipe, which runs horizontal in the drainfield to disperse wastewater evenly throughout the drainfield. |
| Drainfield | A system that is usually below grade, designed to absorb liquid waste after it has passed through a septic tank. The drainfield, sometimes referred to as a leachfield, absorption field, deep trench, shallow trench, mound, or bed, comes in many shapes and sizes. |
| Groundwater Monitoring | A test conducted to find whether or not groundwater is present. A perforated pipe is placed vertically to the bottom of a test hole and then buried. The water level is observed and measured for at least seven days. These measurements aid in the design of a drainfield. For more information, go to the groundwater monitoring section of the soils analysis page. |
| HAA | Health Authority Approval: Has been renamed to Certificate of On-site Systems Approval (COSA). A certificate issued by the MOA which serves as confirmation to lending institutions that the well and/or septic system, serving a single family residence, have been inspected by a professional engineer and have been found to be in compliance with the applicable standards. |
| Lift Station | A tank or chamber accompanied by a pump and related controls used to retain effluent and periodically discharge it. A lift station can be used to pump wastewater from the septic tank to the drainfield when gravity flow is not possible. In some cases, the only place to locate the drainfield is uphill from the tank. Most lift stations are one unit, meaning that the lift station is within the septic tank. These units are called S.T.E.P. Tanks. Separate lifting units are available. |
| MOA | Municipality of Anchorage. Development Services Department, Division of Environmental Services, On-Site Services Section. |
| 4700 South Bragaw Street P.O. Box 196650 Anchorage AK, 99519 (907) 343-7904 Web site: http://home.muni.org/onsite |
| Monitoring Tube | A standpipe for monitoring the liquid level in a drainfield. This page has a diagram on cleanouts and monitoring tubes. |
| Mound | A soil absorption system that is elevated above the natural soil surface utilizing suitable fill material, horizontal perforated distribution pipes, and standpipes. |
| Percolation Hole | A 12 inch deep, 6 inch diameter hole dug within a test hole which is then used to determine the percolation rate. For more information, see the Soils Analysis page, or go directly to the percolation testing section. |
| Percolation Rate | The rate in which water is absorbed in a percolation hole. For more information, see the Soils Analysis page, or go directly to the percolation testing section. |
| Percolation Test | A test conducted to determine the soils' permeability. This test takes place within undisturbed soils, usually within a couple of feet from the test hole at a depth specified by the engineer. A percolation hole is then dug for this test to take place in. From this test, a percolation rate is determined. For more information, see the Soils Analysis page, or go directly to the percolation testing section. |
| PIWA Sample | PIWA is an acronym for Personal Individual Water Analysis. This extensive test is not required to obtain a COSA but performed by many homebuyers. The PIWA includes sampling for the following: Total Coliforms, Nitrate, Nitrite, Chloride, Sulfate, Fluoride, Aluminum, Arsenic, Barium, Cadmium, Calcium, Chromium, Copper, Iron, Lead, Magnesium, Manganese, Phosphorus, Potassium, Silicon, Silver, Sodium, Zinc, Conductivity, Total Dissolved Solids, Hardness (as CaCO3), Alkalinity (as CaCO3), and PH. |
| Primary Site | The designated area for the initial drainfield on an undeveloped property. For new construction, it is required by the MOA to have both a primary and reserve drainfield site. |
| Private Well | A groundwater source serving one single-family residence or duplex. |
| Reserve Site | The area designated for a future drainfield site. For new construction, it is required by the MOA to have both a primary and reserve drainfield site. |
| 3 Bedrooms | requires a | 1000 gallon tank |
| 4 Bedrooms | requires a | 1250 gallon tank |
| 5 Bedrooms | requires a | 1500 gallon tank |
| 6 Bedrooms | requires a | 2000 gallon tank |
| Sewer Drainrock | Rock that is used below the distribution line within a drainfield. This drainrock is used to equally distribute effluent throughout the drainfield. The drainrock needs to be from a MOA approved supplier, and must be one-half inch to two and one-half inch in diameter screened gravel. |
| Shallow Trench | A drainfield that is 5 feet wide and contains no less than 6 inches nor more than four feet of sewer drainrock below the horizontal distribution line. A shallow trench type drainfield uses a combination of side-wall and bottom for absorption area. |
| Soils Analysis | During the excavation of a test hole, an engineer examines and classifies the different layers of soil within the hole. This helps in determining whether or not the site is suitable to support an onsite septic system. For more details, see the Soils Analysis page. |
| Standpipe | Term used to collectively refer to cleanouts and monitoring tubes. |
| S.T.E.P. Tank | A Sewage Tank Ejection Pump (S.T.E.P.) is a combination of a septic tank and a lift station. With a S.T.E.P. tank, the capacity of the tank is increased 250 gallons relative to the amount of bedrooms the system is serving (see septic tank). |
| Surface Water | Any persistent natural or manmade source of water which is not directly attributable to a single rainfall or snowmelt event. |
| Test Hole | A hole that is excavated in the proposed area for a drainfield, to conduct a soils analysis and other pertinent tests. The hole is excavated to the maximum depth possible, usually 10 to 17 feet deep. With this hole, an engineer can classify the soils, determine groundwater and bedrock depths, and test the soil's permeability via a percolation test. |