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The site evaluator did additional soil borings at the corners of an area ap* proximately 32 x 80 feet Soil condi tions were not significantly different from soil boring 2. Only after this adequate area of suitable soil was located were percola tion tests conducted. Since the soil texture at the depth of the trenches was not different, two percolation tests were conducted in the area of the system (figures A and 5). The per colation test procedure used was that given in the Minnesota Pollution Con trol Agency's adopted standards (WPC-40). The average perroiation rate determined by the two tests was 25 mpi. Since this is within the esti mated range, the size of the system did not change. The system was then designed with the 80-foot trenches on the contour so that the length of all trench bottoms were level (figure 5). Drop boxes were indicated to distribute the effluent since this was a sloping site. After the site has been evaluated, the location of the sewage treatment system, watei supply well, the house, and pertinent structures should be con spicuously staked. The area of the pro posed sewage treatment system, and the alternate site if required, must be piotectcd from any disturbance during the other construction activities. Final Report The prospective homeowner should receive a detailed final report of the s.te evaluation. It should include results of each of the soil boring lest holes in cluding notation of texture, depths to mottling and water tables. Percolation test data, both the field readings and calculated percolation rate, should be included. A sample form which could be used for reporting the results is given in How to Run a Percolation Test, Extension Folder 261. which can be requested from county agricultural extension offices. Data should be kept and presented in a neat and professional manner. Each of the boring holes and percola tion test holes should be located on a Figure 5. Proposed soil treatment system desigrt with soil borings and percolation test hole locations. •trench system is OlSIGNEO using a minimum center to center SPACING Of 0 FEET. TRENCHES FOLLOW CONTOURS O SOIL dORiNG holes ® PERCOLATION TEST MOLES SCALE FEET rcale sketch map of the lot which should also include the location of the house, driveway, patio, and other im provements. Location of the sewage treatment system and water supply well should be indicated with setback distances specified (figure 4). This map and data may then be submitted with the application to the local agency which issues permits for on site sewage treatment systems. Town and Country Sewage Treat* ment. Extension Bulletin 304 Get to Know Your Septic Tank, Extension Folder 337 Shoreland Sewage Treatment, Ex tension Bulletin 394 Additional Information The following additional publica tions about sewage treatment systertis may be requested from county agricul tural extension offices or the Bulletin Room. 3 Coffey Hall. 1420 Eckles Ave.. University of Minnesota. St. Paul. MN 55108. The first two listed are particularly useful for site evaluation and design of on site sewage treatment systems. • How to Run a Percolation Test, Ex tension Folder 261 Other Information Sources • County extension director • City or county zoning administrator • Extension agricultural engineers and soil scientists at the University ct Minnesota • Local Soil and Water Conservation District Offices • Minnesota Pollution Control Agency • Minnesota Department of Natural Resources • Minnesota Department of Health • Minnesota On-Site Sewage Treat ment Contractors Association The ,nlormm,on g,von in ihi, publiculion for cducononj purposes only. Rrforence to commcrc.jl products or trade names is made with rhe ur,de,stand.n.j that no tl.scnm.nat.on ,s intended and no cndo.scn.ent by the M.nnesota Agricultural txtens.on Sr,v.ceT,mpZ! access to rts programs. crimes, and employment «.thout regard to race, creed, color, sex. nal.unal or.g.n, or handreap. ,5