The URL can be used to link to this page

Home My WebLink About1996-04-05 Letter, Site EvaluationDevelopment Engineering, P.A. 9051 Flying cloud Drive Eden Prairie, MN 55347 Fax: (612) 941-3030 5 April 1996 Mr William Waldron 1880 Fox Street Wayzata MN 55391 Re: SITE EVALUATION 5 SYSTEM DESIGN Proposed Onsite Wastewater Treatment System 1880/1.860 Fox Street, Orono, Minn Protect 95-127 As per your request and authorization, we have completed a Site Evaluation, consisting of seven soil borings, eight percolation tests and other work, at the above referenced location. In addi- tion, we "prospected" in other areas to get an over-all view of the total parcel. The purpose was to assess suitability for onsite treatment of wastewater and to determine design paramaters. Please accept this letter and attachments as my report. We understand that you are required by Orono to replace your functioning but non -con- forming systems. We originally set out to perform two site evaluations; one for your main residence at 1880 Fox Street << d one for your smaller house at 1860 Fox Street. However, due to various rules of both Minnesota and Orono (eg, max 6% slope, 75' wetlands setback, no system on fill, etc), we were unable to locate a site meeting requirements on the 1860 Fox Street tract, nor could we locate one on the 1880 Fox Street tract just north of the property line between the two. Ul- timately, we settled upon one common site northwest of your main residence. The land in the area t is fairly uniform, with slopes of 5.7% in the upper portion, i the lower portion. Site vegetation consists of mainly of s! 3intained grasses, with some small trees and brush in the a ortion. We anticipated clay soil and a high restricting layer (a, -ing). We ultimately located two areas, a primary s.te and an alteLnate site, after some setback measure- ments, field pre -design, etc. We chose this area as we judged it to hold the best potential to ultimately meet all requirements. Test locations and relevant topographic data wwere were determined using an engineer's total station instrument. Locations are shown on the attached sketch. They were additionally marked in the field with lath. Ground surface elevation at each test point and at other necessary points were also determined, Bench mark used is the top Mr William Waldron 5 April 1996 Page 2 of an iron property monument between your tfdcts. This temporary datum was assigned an arbitrary reference elevation of 100.00. Attached are logs of the borings. They were accomplished by the hand auger method for greater accuracy. The borings generally in- dicate normal topsoil, generally an organic loam, of normal depth in upland areas, thicker towards wetlands. Basal soils are clay loams, soft at first, medium with depth. Soil moisture levels var- ied considerably. All borings were terminated at 2.5' to 51, less than the usual 8' as restricting layers had been encountered. Refer to the boring logs for a more detailed description (color, ocisture level, gravel contents, etc) of soils encountered. Standing vat )bserved in the bore holes. However, and more imports ng of soil was encountered between 1.6' and 4' of depth Is. Mottling is a certain banding or stain- ing of soil. r dhen soils are periodically saturated. It is usually *a" nce of a past, and thus future, groundwa- ter fluctuation. LOW;. of treatment systems must be separate from maximum anticipateu water, perched or otherwise, by at least three feet. Hence, you will need a mound system as higherst mottling is 1.6' below surface level. We separated the site into two areas, a primary and alternate site, and prepared six test holes in the lower area and three test holes in the upper area, each to a depth of 13"-14" below present surface level. This shallow depth establishes percolation rates of soils that will be in contact with oroposed systems. Soils encountered are essentially consistent with soil boring results. As the initial fill of 12" of water did not drain out of the percolation teat holes in less than 10 minutes, holes were kept wet for the required 4 hours. Tests were performed the next day, in accordance with Minnesota Rules Chapter 7080. In some instances, the recording in- terval was adiusted so that i approximate drop in water level of 1" between readings was eff... Led. Transcribed forms of the percolation tests showing recordings and other data are enclosed. Original data sheets are on file with us, should anyone wish to view them. Reults are as follows, all within allowable design ranges: Test Hole No Percolation Rate, min/in 1 5.3 2 7.4 3 5.1 4 17.4 5 7.9 6 10.5 Mr William Waldron 5 April 1996 Page 3 7 8.7 8 .9 9 lu. Average 7 (ground s'_ape = 5.7%) The above data together with some initial judgments as to construc- tion economics confirms that the only allowable treatment system on the site is a wa;-;tewater treatment mound. The mound type of system is necessary to clear the zone o' = sonal saturation as indicated by mottled soils. It may be locat.., in either area tested; with the remaining area reserved as an alternate site, at separation dis- tances required in MR Ch 7080. Based upor an estimate of wastewater flow for a 5 BR Type T resi- dence (750 gpd), A i dR Type I residence (300 gpd), the percolation rates, and other data, we have generated a detailed system designs for two possible onsite systems. They are enclosed in triplicate together with design calculations, detail sheets and schematic drawings. Special attention is drawn to the following: - The 'Lower area was chosen as a primary site due to ir.s .latter slope and more out of the way location - Each residence has its own septic tank(s), sized assuming a gar- bage disposal in each 'itti '_ly treated wastewater will flow by gravity to a pumping amber ^n the 1880 property e deal _n consists of one long treatment bed and the her of a dual bed; th- dual bed takes better advanta(v- of the existing land form and requires less intrusion into t,F. area of woody vegetation We suggest s*t bids un both 5y5tems and _ or— based 14pon your. t.iiteYia (cost, aesthetics, etc) Data is 613o attached to each design showing that the alter- nate site size is sufficient. Your next step is to select an installer P with hi- )— 4, pro- ceed tr obtain a permit f9r the system t' e f Orono. The only additionai advisory is that TV- 'EM AREAS BE IMMEDIAT:aLY OFF-LYMITS TO TRAVEL by and THE AREA SHOULD F& BARRIEREt Tu PREVENT THIS T. 4F. i.s .3scause such travel sill cow..pact the soi ossibi, :he pe;cColation rate which c.s ':d lea.? system failure. In r ^;usion, I mu,t staff,:% that, because the boring and test holes ireaent only a smn_1 port - of the total site and for other rea- %A3, we o..-.. n.nt warrant that the boring --id to-t holes are repre- sent?t-lve of the entire sit, ut only of the b.r; i and test hole locations at the time of investigation. Review (` construction should be an in*- -al part of this. design to enhance the likelihood of hi ; ng a able system. N^, warranty of the sites is made or M7 William Waldron 5 April 1996 Page 4 I have backfilled and compacted the bore holes and percolation test holes as vell as possible under existing conditions. Hovever, some continuing s.ttlement may occur. If it does, it should be back - :.led with suitable md-r#�sial. •aby certify th4t, at the time of the field vork, I vas certi- La' to perform site evaluations and to design systems under the provisions of MR Ch U80. I further certify that,f at the time of the field work, our firm was licensed to perform site evaluations and to design systems in Ji4;n-o under City ordinances. I Putt?k-tr certify that ve have applied to the State of Minnesota for a Designer II license under new provisoes of MR Ch 7080. Respectfully submitted, DEVELOPMENT ENGINEERING, PA �� J Pafrick J Hines, PE ISTS Cert No 1503 PH enclosures