Text Size
Sunday, January 21, 2018

Conditions of Services COSA Work

All costs associated with obtaining a Certificate of On-site Systems Approval (COSA) from the Municipality of Anchorage (MOA) are subject, but not limited to the following conditions at the time of testing:

  • A legible copy of current as-built survey is provided.
  • All septic pipes are present and exposed (not buried underground or in the snow).
  • All septic pipes are functional (not broken off below ground, or filled with dirt/rocks).
  • The well production is adequate enough to fill the septic system in a reasonable amount of time (at least one gallone per minute).
  • The Septic tank is pumped per Engineer's direction.
  • If the house has been vacant in excess of 60 days, the leachfield will need to be presoaked (required by the MOA) prior to testing, at an additional charge.
  • Well head is accessible and the sanitary cap is functional and removable.

    In conducting this evaluation, GEG, Ltd. will provide a thorough, conscientious engineering analysis of the system in accordance with ADEC or MOA guidelines & regulations. The reported results will describe the performance of the system under the conditions encountered at the time of the test, and separation distances measured to readily identifiable features. The operational life of all wells and septic systems depend on the local soils conditions, groundwater levels (that may fluctuate during the year), the water usage of the family being served by the system, and other factors. These conditions are outside the control of GEG, Ltd. Satisfactory test results do not guarantee future performance of the system, nor do they guarantee that there are no hidden defects or encroachments. GEG, Ltd can therefore not provide any warranty or future estimate of how long the system will continue to meet the operational requirements of the ADEC or MOA. The content of our report is for the sole benefit of our client. Any reliance upon or use of this report by any other person or party is not authorized, nor will it confer any legal right whatsoever.

Typical Septic System

The conventional septic system is the most common method used for onsite wastewater treatment. There are a few different variations of conventional septic systems, but they all generally work the same. Click on the link below for a diagram of a conventional septic system. As you can see the system consists of the following components:

  • A sewer line which carries wastewater from the house to the septic tank.
  • A septic tank which serves as a basin where the settleable solids and floating debris are trapped and removed. The clear liquid from the septic tank has soluble organic material in it and some fine suspended particles.
  • The septic tank effluent passes to a drainfield where it is absorbed into the soil. The drainfield is a either a bed, deep trench or shallow trench excavation that is filled with drainrock and perforated pipe that serve to distribute the wastewater into the surrounding soils. As it is absorbed into the soil the wastewater is filtered and treated so that it is purified prior to reaching the groundwater.

All septic systems have standpipes that extend above the surface. These pipes are not only there to add beauty to your yard, but also to allow for inspections and maintenance. Although the standpipes may all look the same from the surface, they all have different and important jobs. All cleanouts have been installed for maintenance purposes. If cleanouts were not installed, an excavator would have to dig up the system in the event of a clog. The monitoring tube allows for measurement of the liquid level in the drainfield.


Now that you have an idea what a septic system is, we can get a little more in-depth. Here are some more links that will answer some of your initial questions and some new questions about soils and alternative technology systems:

Tell me more about cleanouts and monitoring tubes

Tell me more about septic system testing

What is an alternative technology septic system?

Engineering costs and permit fees


BioCycle Treatment System

The BioCycle is a residential sized wastewater treatment plant that is designed to treat household wastewater before it is discharged to the drainfield. The BioCycle, like the other AWWTS systems, provides an aerobic environment in which microorganisms flourish by consuming the organic wastes. By reducing the strength of the organic waste, the wastewater coming out of the BioCycle is cleaner than what would come out of a conventional septic tank. As a result, the MOA, Development Services Department allows a reduction in the size of the drainfield versus what would be required for a conventional septic system. The benefits are as follows:

  • Drainfield sizes are reduced by as much as 75%. The BioCycle installation will reduce the aesthetic impact (less lawn and trees destroyed), enhancing the value of the property.
  • Small lots which could only support a 2 or 3 bedroom conventional septic system can often install a BioCycle in the same area that will allow for up to a 5 bedroom house. Again, enhancing the value of the property.
  • The life of a drainfield served by BioCycle system should be more than that of a conventional septic system.
  • On undeveloped lots which are very small, the BioCycle system makes it easier to find room for the primary and reserve drainfields. Because of the reduction in drainfield size, only two small drainfield sites would be required. In short, a lot that may have not been developable with a conventional septic may now be a developable piece of property.


In theory, if properly maintained and operated, the BioCycle system is capable of producing an effluent that will not biomat, and fail the drainfield.


Costs for a BioCycle installation, including test holes, engineering, permits, and contractor fees, typically averages $25,000 - $35,000. As is the case with the other Advanced Wastewater Treatment Systems (AWWTS), the price is not cheap; however, the benefits may out weight the costs.

Intermittent Sand Filters

The most common type of intermittent sand filter (ISF) system is termed the bottomless ISF. Such systems consist of a small drainfield underlain with 2 feet of sand. An air line in the sand feeds oxygen into the drainfield. This keeps the microbial environment oxygenated and the microorganisms "happy." Wastewater (the bugs call it food!) is fed to the drainfield in small doses throughout the day, by way of a lift station equipped with an intermittent dosing timer. The bugs consume the nutrients in the wastewater and convert it to cell mass the same way humans convert food into muscle and fat. The wastewater is treated as it passes through the sand and is then absorbed in the soil underneath the sand. In theory, the intermittent sand filter won't develop a biomat and clog-up like a conventional drainfield can. Enough of the engineering technobabble? What really matters is how this technology can help you. Here are several examples.

  • Drainfield sizes vary from 18' by 20' to 12' by 30'. These fields will serve up to five bedrooms and take up very limited space, reducing the aesthetic impact (less lawn and trees destroyed), and enhancing the value of the property.
  • On small lots which could only support a 2 or 3 bedroom conventional septic system, the installation of an ISF in the same area can allow for up to a 5 bedroom house. Again, enhancing value of the property.
  • The life of an ISF should be significantly more than that of a conventional mound type system, which have proven to have a high premature failure rate (many have failed in less than 5 years).
  • On undeveloped lots, which are very small, it is easier to find room for the primary and reserve drainfields, since only two small ISF sites would be required. In short, a lot that may have not been developable with a conventional septic may now be a developable piece of property.


Clearly, if you are trying to sell the property, these benefits correspond to increased marketability and a faster sale.

The cost for the bottomless ISF system (Year 2016), including test holes, engineering, permit fees, and contractor installation can range from $25,000 - $30,000. Not a small price tag, but if it makes a previously "worthless" piece of land into a homesite, or takes a house off of a holding tank, it is a bargain price. For more information on ISF systems, please contact us.

garness new logo


Garness Engineering Group, Ltd is a 100% Native American owned business enterprise.

 State of Alaska DBE Certification # 9900155

 Download Statement of Qualifications (PDF)

Product Line • Alaska Authorized Dealer
Quanics-logo logo-xerxes-2