MPCA SSTS Bulletin

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SSTS Bulletin

April 2013

Percent of mound installs increasing; still less than half

A common perception seems to be that more and more mound systems are being prescribed for new installations in Minnesota than in the past. While SSTS annual report submissions for 2012 do indeed show the percentage of mound installations compared to other types of septic system installations is rising, the rate of increase has been fairly gradual over the past 12 years.

"The total number of mound systems installed in 2012 was reported at 3,575, out of a total of over 9,182 systems," says Barbara McCarthy, author of the 2012 SSTS Annual Report, which is being prepped for general distribution. "The proportion of SSTS constructed that were above ground systems (mounds and at-grades)  has increased over the years, from just over 30 percent in 2001 to 45 percent of the systems installed in 2011 and 2012. The reasons for the increasing number of mounds and at-grades could be that: 1) sites for SSTS are getting tougher for new and replacement systems and 2) the evaluation of soil conditions and recognition of seasonally saturated soils are improving."

Increased soils training (six CEU’s every three years) has been a requirement for designers and inspectors over the past few years. Barb says this may have helped to improve both designers and inspectors knowledge and recognition of indicator soil conditions that would necessitate the need for an above ground system. Soil verification by local permitting authorities is important to ensure that the right types of septic systems are being installed in Minnesota.    

The following graphs show the number of various types of SSTS installations in residential settings in 2012 (Figure 7), as well as the percentage of mound and at-grade systems installed over the past 12 years for all reported installations (Figure 9).


If/when spring arrives, only registered tanks will do


By Gretchen Sabel

As requested by several local units of government, the MPCA has sent letters to all licensed SSTS installers (1,010 in all) reminding them that only sewage tanks registered with the MPCA and listed as such on the MPCA website can now be installed in Minnesota.

The MPCA will continue to work with manufacturers that wish to register sewage tanks. The registered tank list on our website is continually updated as new tanks are added.

As we work through the tank verification process with the tank manufacturers, we at the MPCA have become aware that many of the older model tanks that were sold do not meet the soil-bearing capacity required in the old or new rules. By choosing tanks from the MPCA list you can be assured that the tanks you use are tested and have been shown to meet the standards.

Installers were also reminded to, if they haven't already, sign-up to receive by email the MPCA SSTS Bulletin, which is how the agency now shares important information and updates with stakeholders. If people are unable to access the Bulletin via computer, they can request in writing to receive a hard copy by mail. "We are making this option available because we want to make sure we reach as many licensees as possible," says Gretchen Sabel.  "We will be sending letters to some of the other disciplines in the coming months and will offer this alternate format in those letters as well, focusing on those for whom we don’t have email addresses."