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Alternative Technology Systems (ATS)

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If site conditions prevent the installation of a conventional septic system, then it may be possible to install one of the alternative technology systems. The systems currently being used in the Anchorage and Eagle River area are as follows:

Wastewater treated by these systems can be discharged to a much smaller drainfield, and in some cases can be as close as 2 feet to groundwater. The cost of installing these systems varies widely, depending on the accessibility of the site, the soil conditions (tight soils require a bigger system), topography, etcetera. In general you can assume that the total costs (test holes, engineering, permits, and installation) will run from $20,000 to $25,000, excluding re-landscaping of the site. Not cheap, but in some cases the installation may bring enough added value to the property to more than offset the costs over a conventional system. The design criteria for each of the systems are summarized via the links above.

Cleanouts & Monitoring Tubes

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In areas that are not serviced by public sewer, such as much of Eagle River, Chugiak, and the Anchorage Hillside, conventional onsite septic systems are the standard method for residential wastewater treatment and disposal. Unfortunately, there are numerous properties with restrictive site conditions that prohibit the installation of a conventional septic system. In such cases, it is often feasible to utilize one of the alternative technology septic systems (ATS) to develop the property.

This web page describes site conditions which preclude the use of conventional septic systems and the types of ATS systems that can overcome these restrictions. This information can lead you to a more informed decision on property transactions.

We would be happy to do a full engineering evaluation of your property and recommend the septic system which best meets your needs.

Challenging Site Conditions

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PROBLEM AREAS:

There are a number of locations in the Anchorage and Eagle River area where site conditions are unsuitable to support a conventional onsite septic system. In the past, many of these areas were developed, only to find out later that the septic systems would not function properly. Many of these homes have since been put on holding tanks, and others are utilizing some alternative technology systems which are now available. Before determining what systems are viable for any particular lot, there must be a thorough engineering evaluation of the site conditions. Conditions which may prevent the installation of a conventional septic system are summarized throughout the next few pages.

 

RESTRICTIVE SITE CONDITIONS:

 

  • The topography is too steep (slopes greater than 25%): The drainfield must be at least 50 feet away from a downhill slope greater than 25%. The MOA will waive this on a case by case basis.
  • Shallow groundwater, such that there is not 2 feet of unsaturated, naturally occurring soil: The bottom of a conventional drainfield must be at least 4 feet above groundwater.
  • Soils which percolate too slowly: If the percolation rate is between 60 and 120 minutes per inch, then an ATS will be required. If it takes greater than 120 minutes for the water level in the perk hole to drop 1 inch, the soil is unsuitable for any type of septic system.
  • The protective well radius' encompass all of, or a major portion of, the land area necessary to install a conventional septic system:
    1. Private wells (single family residence and duplexes) have a 100 foot protective radius
    2. Class "C" wells (serving less than 25 people) have a 150 foot protective radius
    3. Class "A" or "B" wells (serving greater than 25 people per day) have a 200 foot protective radius
  • There are nearby surface waters, such as creeks, ponds, lakes, etcetera: The septic system must be at least 100 feet away from any surface water.
  • The area groundwater supply has high concentrations of nitrates (by-product of sewage decomposition), causing the MOA to prohibit the installation of additional onsite septic systems in the area.
  • Very shallow bedrock: The site must have at least 2 feet of naturally occurring, permeable soil over the bedrock.

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3701 E. Tudor Road, Suite 101  ♦  Anchorage, Alaska 99507-1259
Phone: (907) 337-6179  ♦  Fax: (907) 338-3246

 

 


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