Health board changes septic regs

In January, all new or rebuilt septic systems in Flathead County must employ uniform pressure rather than gravity distribution of sewage.

Passed by the health board Thursday, the requirement was included in amendments to Flathead County's regulations for sewage treatment systems. The amendments aim to improve sewage treatment to better protect ground water.

Health officials point to the rapid growth in rural areas not served by municipal treatment plants as the motivation for the new rules. With more sewage entering from on-site treatment systems, the danger of polluting drinking water increases.

Flathead County Commissioner and board member Bob Watne was the only member to vote no.

"You're going to put a lot of stress on young people trying to get started in this valley," Watne said before the vote.

He referred to the cost of a pump, controls and larger tank required in uniform pressure-distribution systems

Health department officials placed those costs at $820. However, they say savings in the trench excavation size, media placement, piping plus extra system life cut $380 off the pressure-distribution system investment.

In gravity systems, sewage leaves the residence and enters a tank where solids sink to the bottom and liquids flow out a pipe at the top into a network of pipes called a drainfield. The liquids exit through holes in the pipes and percolate into the ground.

In pressure distribution, a pump in a second tank chamber pushes sewage out of the tank at timed intervals down the full length of the drainfield pipe network.

Health department engineer Dick Montgomery said the timed "dosing" down the full length of the drainfield allows microbial agents to efficiently clean contaminates from the liquids before they percolate down to the ground water.

He said sewage in gravity flow systems doesn't make it through the network. It loads up in the front of the drainfield pipe network, leading to less efficient microbial cleansing.

Only one citizen addressed the regulation changes at the Thursday meeting before the board vote.

Ray Galloway, a professional installer, claimed costs will rise from $2,500 for gravity flow systems to $4,500 for pressure distribution. He said that was the cost of recently bid systems.

Galloway added that drainfield plugging was a common problem with pressure-distribution systems.

Health Director Joe Russell responded that part of the cost Galloway cited was hiring an engineer to design the system. He said the department plans to train installers to design most systems as part of its certification course.

Russell said that the regulations addressed the plugging problem by requiring construction of systems that allow access to lines for cleaning. He said earlier plugging was not a problem in properly sized and installed systems.

Although only Galloway spoke at the meeting, the public hearing held in October drew comments from both supporters and detractors of pressure distribution septic systems.

Montgomery responded to concerns raised at the public hearing in remarks to the board before the vote.

Along with the cost comparisons listed above, Montgomery responded to installers' request that the department require pressure-distribution only on "loose" soil that percolates quickly.

He cited calculations that took into account percolation rates and drainfield sizing. Those with "tight," or slow, percolation required septic systems over 1,000 square feet for a three-bedroom home.

Montgomery found that pressure distribution actually offered savings over a gravity system in the tight soils for which contractors suggested an exemption.

Also prior to the vote, sanitarian Glen Gray presented a letter from a Lake County sanitation worker that supported the use of pressure-distribution systems. Lake County has required this type of system for 10 years without significant problems.

Reporter Candace Chase may be reached at 758-4436 or by e-mail at cchase@dailyinterlake.com