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Mr. McNamara provided information regarding city requirements. They include: conformance with Minnesota Rules Chapter 7080 for the the design, location, installation, use and maintenance of individual sewage treatment systems, managing building and sanitary permits, requiring certified people to be involved in site evaluation, design and construction, and requiring at least one boring and one percolation test per site. Mr. McNamara indicated that the city does not get involved in determining whether a site is "buildable" or not until a building permit is requested (the MPCA defines buildable as "can it accept an onsite system"). When the building permit is requested, the city then requires a soil boring and percolation test to be completed. Variances to 7080 would be processed through the city if requested. COMMENTS Minnesota Rules Chapter 7080 were written with the intent to install onsite systems on natural, undisturbed soils. Tests have been done to indicate sizing requirements for different types of soils. Onsite systems placed on fill have not been tested and standards have not been developed. That does not mean that systems placed on fill will not work, but it does mean that you are taking and accepting a risk. Apparently the developer has decided to take the risk but is reducing the risk by installing curtain drains and using clean sand as fill. Curtain drains, although routinely used, have not been shown to eliminate problems caused by high groundwater tables. Curtain drains (drain tiles) work well in farmer's fields because they are built to slightly lower the watertable. New crops need only a few inches of unsaturated soil to begin growing. To obtain treatment in an onsite system, Chapter 7080 requires a three foot separation between a limiting soil characteristic, like watertable or bedrock, and the bottom of an onsite system. Design of a curtain drain system must be done by an experienced designer. Mr. McNamara indicated that TKOA has been responsible for the design. The MPCA routinely recieves calls about curtain drains and would be interested in adding TKDA's design and piezometer data to our technical files. Based on our observations, the curtain drain was of sufficient distance and sufficient depth (providing the onsite system is built with.a 3' separation) such that the tile should not carry untreated sewage unless saturated soil conditions occur. Mr. McNamara does not have building and onsite designs yet, but expects either shallow drainfields or mounds to be built with the drain at least ten feet from any installed onsite system. If there are suspicions of sewage in the tile discharge, the discharge should be tested for fecal coliforms. There should be no evidence of fecal coliform in the discharge. Discharge of sewage to the ground surface is considered a public nuisance and can be enforced under Public Nuisance Laws. The problem occurs in determining who is responsible for the discharge (an evaluation of each onsite system would have to be done) and what can and will be done about it. It would be best at this time to discuss the design details with the consulting engineer at TKDA to see how the curtain drains have been designed and to raise the concern with the city so any possible building or sanitary permits watch for designs where the onsite system has been placed in an area without sufficient locationiof.theeonsntessystema1so not allow further If mounds are built, we recommend conducting a jar test as defined in the definitionagrequiredmfor mounds.nt Manual toCertifiedhpersonnelaaremfamiliar withclean thissand test and the need for clean sand. Unclean sands will inhibit the wastewater from travelling through the soils, causing seepage or drainage out of the side of the mound. E'd 71-lno-8ium,/Aoou iaio Hoiin-nod NW WdSS:t7O 76, TO wnf