Another View on Hydraulic Load Testing

Not everyone agrees that HLT is the way to go for a point-of-sale inspection

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As hydraulic load testing gains more attention as a way of determining if soil treatment areas (STA) are effectively handling effluent, there are some who think it adds unnecessary expense and complications. One of them is Dawn Long, owner of American Septic Service in Sierra Vista, Arizona. She sees a comprehensive inspection of the septic system as a more efficient way to determine if a system is operating properly.

Long is a regular presenter at the Arizona-based NAWT inspector training course and holds certificates in soils identification and septic system evaluation and design. While NAWT has developed a standard operating procedure for HLT, she views it as having limited value. “By using a thorough inspection of the septic tank and a simple flow test, a conclusion can be drawn as to the soil’s ability to receive and disperse wastewater without hydraulic loading,” she says.

One common use of HLT is for homes that have been vacant prior to a time-of-transfer inspection. “When a structure has been unoccupied and the STA is dormant, science has proven that the biomat dissipates and the area recovers,” says Long. “The best tool for time-of-transfer is a comprehensive inspection of the septic tank, because this is where all the clues are for concluding a system’s overall health.” In Arizona, she adds, a time-of-transfer inspection has 60 items on the checklist, so a full inspection is necessary anyway.

Arizona has also required observation ports at the end of the drainfields since 1990. “Inspecting the ports verifies that effluent is moving through the system and reaching the STA,” Long says. “Performing a hydraulic loading test would be a useless, time-consuming endeavor.”

Long’s approach is to first do a camera inspection of the drainfield looking for sludge buildup, roots and broken pipes. After that, she suggests running water into the system to observe the flow as it moves through the perforated delivery pipes. The objective is to rule out obvious warnings of impending failure and has nothing to do with the soil’s ability to absorb effluent.

She says some of the additional work and expense required for HLT include:

  •       Two additional hours for the inspection
  •       Up to three trips to the property in three days
  •       From 200 to 675 gallons of water, which may or may not be available on site
  •       Additional excavations and modifications

She adds that HLT uses too much water at a time when more areas are struggling with water shortages. “There are numerous ways to determine an onsite system's ability to function without using a lot of water, the world’s most precious resource.”

Do you use hydraulic load testing for time-of-transfer inspections, or do you agree that another method is more beneficial? Leave a comment below or email kim.peterson@colepublishing.com.



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