2022 05-17 CC PACKET - Laserfiche WebLink

Home

The drainfield/soil treatment system The effluent from themptic tank moves to the soil treatment system, such as.a mound, trench, or at=grade drainfield. A trained SSTS professional.must take soil types and other facto.rs into account when.designIng the correct type of septic system for a specific site.. The effluent moves either by gravity or using a pump; through distribution pipes in the -soil treatment system, and down through the distribution mediiam:to its base where the distribution medium meets the underlying soil. That's where.a sticky biological layer (biomat) forms. The biomat slows.. the infiltration of effluent into the underlying unsaturated soiil,.and further filters out pathogens and solids. The biomat can slow effluent movement to as much as 100 times less than its normal flow rate; this:helps maximize the contact time between the effIuent.and the surrounding soil particles. Soil particles are negatively charged. Through a process called adsorption, they attract.and hold the positively charged pathogens <1n the effluent. 0nce.held, the pathogens are easily available to theaerobic. bacteria inthe air pockets.between the soil particles. The aerobic bacteria,.which are much more efficient than th.e anaerobic bacteria in the septic tank; continue treatment. Other forms: of bacteria also begin to grow., producing slimy films over the soil particles; which act as.additional filters to "grab" pathogens. It is important to properly site the SSTS with the existing soil conditions to ensure maximum treatment occurs. If the site is not optimal for treatment (e.g:, it has :a: high .s.easonal.water table), it. won't offer effective soil treatment and the riskof contamination.increases.. SSTS regulations in Minnesota. The 1968 Minnesota Shoreland Act required septic systems to be evaluated and managed properly within .shoreland areas to -better control their impact on water quality. But the first state law specifically addressing septic systems wasn't enacted until 199.4: the Individual :Sewage Treat ment:Systems (ISTS) Act .(Minn. Stat. §.§ 11S.55 and 115.56). It requires all new construction and replacome nt'septic systems. to meet minimum standards. It also enacted a. system to upgrade failing existing SSTS before construction of an additional bed room, .a.nd methods to replace failing SSTS within certain timeframes. The 1994 act has been amended in recent years; with major.changes in 1996.and 2008. Regulations will continue to be amended as the SSTS. industry advances.. More information Visit the Minnesota Pollution Control Agency website. at http://www.pca.state.mn.us. Page 2:of 2 June 20M 1 wq-ww)sts1-10