2019/01/18 - SANITARY - SAN - Repl Mound >24" - SAN-18-139

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Page 2a + b of 8 Individual Site Design and Plan Narrative The objective of this individual site design is to create a sanitary system design that will serve a new four bedroom replacement structure. The property is located at 27283 East Devils lake Rd. and is owned by David and Laura Fitzpatrick. The legal description is: Lots 12 and 13 of the Colter's Subdivision located in Gov. Lot 2, Sec. 34 T40N-R16W in the Township of Oakland in Burnett County. The parcel is a .80 acre lakeshore lot with limited area to support a sanitary system due to soil conditions, slope constraints and well, lake and structural setbacks. Because fill material consisting of an existing 12 ft. x 42 ft. aggregate drain field was documented in the soil profile borings, and a 2-3% cross slope over which the new dispersal area will be located I will be unable to complete a sanitary design using the mound component manual recognized under SPS 383.60(l). SPS 383.44(3) (b) 1 states that a POWTS designed utilizing a component manual recognized under SPS383.60 (1) shall have at least 6" of the minimum 24 -inch soil separation required under par. (a) shall be an insitu soil type for which soil treatment capability has been credited under Table 383.44-3. These filled sites require plan approval to be applied for as an individual site design. Individual Site Designs require documentation that will support treatment and dispersal claims about the site. Individual Site Designs do not require the 6 inches of insitu soil, however we still need to evaluate and be confident that the intent or rationale of the 6 inches of suitable soil is met on our site assuring that the influent will be assimilated into the subsurface soils and treated without ponding on the ground surface. This individual site design as previously stated has two design parameters that deviate from the standard component manual mound system design due to the limited area available for locating a replacement sanitary system. The following are the specific deviations and a discussion on how we hope to achieve code equivalency. I will first discuss the soil conditions above the existing drain field. Boring #3 is an extension of B#2 showing a sandy loam surface horizon with a moderate, medium sub -angular structure to a depth of 4 inches. The 2"d horizon shows a mixing of subsoil materials consisting of moderate, medium structured sandy loam, and single grained loamy fine sand and some well structured clay ped inclusions to a depth of 34 inches below grade. The next 6 inches of documented soil was a similar mix with redoximorphic features. These features indicate that at some point in time the soils were saturated above the systems aggregate surface. Digging deeper into the aggregate I found that it had been infiltrated by loamy fine sand and fine to medium tree roots. The aggregate was basically clean and there was no visual evidence of a clogging mat or saturated soil conditions. This would indicate that the cabin has seen no or little use in the past few years. As the Fitzpatricks purchased this parcel in June of 2014 and currently have a separate cabin they use to the north of this parcel. Note: as we move upslope the separation between the aggregate and ground surface increases by approx. 7 inches. The Burnett County zoning office found the sanitary permit # 574 for this site and an installation date of 1985. This date is important in that it would mean that 33 years worth of growing seasons have passed including the freeze and thaw cycles to settle the fill and provide sufficient time to repair or create soil structur By using a.4 gal./sq. ft. basal loading rate we will provide a sufficient area for the treated wastewater to infiltrate the disturbed soils and provide a margin for our cross slope issue as well.