Loading...
HomeMy WebLinkAbout1981-05-04 Septic System Design ReportTO: Jeanne A. .Mubusth, Zoning Administrator FROM: Michael P. Gaffron, Septic System Inspector DATE: May 4, 1981 _ SUBJECT: Septic Testing, McCleary Property, 3445 Bayside Road #589 I have reviewed the site evaluation report submitted by Carl Borg on behalf of Mr. McCleary, and wish to make the following comments: 1. Testing was done the beginning of April. In nearly all holes the water table was found to be at a depth of 1.0-1.8 feet below the surface. This coupled with my borings in December 1979 indicate that the water - table fluctuates, but is probably at least 1 foot below the surface during most of the year in the areas tested. (which are the highest portions of the property) 2. Percolation tests were taken at a depth of 15", and where water table was below the hole an average percolation rate of 17 minutes per inch was found. The black silty organic clays of the site are underlain by seams of sand and gray silty clay. 3. Based on the above findings, it seems that the major limiting site factor is the water table, which normally for a mound system would have to be at least 2 to 3 feet below the surface as a minimum. The design proposed by the applicants site evaluator includes adding a layer of fill from the sate over the natural surface to increase the depth to water table to 2 feet or more. This appears to be the best method as long as A) the material used for fill is essentially the same organic silty clay as that on the drainfield site; and B) the fill material and existing soil are Plowed or scarified to minimize any layering effect that could occur, which might create a permeability boundary and cause lateral seepage. 4. The proposal incorporates a separate rockbed for each house within a single sand mound/berm. This method will allow for separation of each residence's effluent and will help to determine liability should system failure ever oc.:ur. 5. The existing well/hand pump system should be properly filled and sealed prior to any constriction on the site. Septic Testing, McCleary Property May 5, 1981 page 2 6. Inherent in Ue design proposed are individual separate septic tanks and holding tanks for each residence. These should be loca,.ed on the individual lots so that the only pipe(s) crossing lot lines are the three pres..sre distribution manifolds from the residences. 7. The proposed design meets criteria for a mound system within the sheet flow floodpl.ain area. 8. Further items needing tc be addressed include: a) Can the proposed layout be constructed within the applicant's proposed lot line arrangement and still allow for a driveway on the common lot? A scaled site plan should be submitted for review, showing all proposed improvements. b) What are the provisions for an alternate drainfield site? If none exists, I would recommend that if failure occurs, the holding tank system for all waste would be required. c) Subheading (3.) of my memo of 1-21-81, still needs to be addressed. (Ownership and responsibility for maintenance and repair) For the record, the technical justification for allowing a graywater mound/holding tank system on this site is a) adequate area exists for a mound system; b) adequate percolation rates were demonstrated where the water table permitted; c) the proposed system is designed to compensate for the high water table. (Note that, normally, no system would have been allowed in this area, and holding tanks as well as the mound system are a variance to the on -site ordinance).d) the holding tank/graywater combination will reduce the on -site treatment required for: BOD - by approximately 50% N - by approximately 80% P - by approximately 50% Total water use by approximately 40% (Based on Manual of Gray Water Treatment Practice Table 8 p. 77) Hence the system will not have as great an impact on the soil/water system of the area as a total mound system would, a^d should not create any undue pollution or health problems for the area. p' StL OatpaQ MOu W, LAVOYT M`r+ FILL FQDrn btTy UZc LGA-M-,LO 0.16►W C 1 tilOT��' �. GosaSZRLUC-Ic) Dt:Th\O iHVvjN S ►t qu- % IL 10 %T Y c1F G►�o►�J� . �,� SITS Afec TiCLNTT SY!L E f-1 IS % L Z. THE ZOP ClGMT (►J�.Ha: Ui CK�:T�N'� � ' \7 QL1 J W t', S 1+ it POLO. 3 c t . v iZ pt+j�ItiO vQt01_ i u PR- mC- t &.ACV T M a F ti RS" i"tJYdJi " IL)Cl4rr-; taK GLLbc.TicO cslt.46Aa1L, SOIL, .ry �J+C.t ►� 4 Sk►� p . s 11lQnU 0tz 'fig F- Mt>ua14 GOTt. �. Dui : v 't.► is 64 % C w w "&IL. TAT& b i i tea. '43 �c IJ GCL. E S ^v-v Te. /4p� ► Ca ue rG a_ VLC4 K-C I 1 On! ALL -r^WkS O.:MP1�G L44 Atr\Ts&Vs.. A T� �.: 'L C. .t4 ng: Co tiL "TL laAU.A&r EgcJ'wCT 0Nt" VIT. 4L �Jh11�,A'ib. MW� a .5 -J [ u L-bL Ta%C-- CjRiYMIA1tQ • 1` rtY R l -U. . ' w C ��1 ,}u, • � fi PQOPd'lt10 �'tz t Z> �,-• r, - GkE �• �i h; �, r W.�•.-.� �t•�� LOB � � twu� { i , `\ �000 CAL StrTtC ih•+ �A f---t}--�---�3---------�-- y--�i 'r N - TOOCc CAS S i;.c, _ o �Q r.Olr� t►.1 G i h N r� / � �' O � � r L^ M - Rock BEn FOP- / 'PROP q Al MOuw p GREY vJA cR / + WJ�S: G' sT c►r, . / F i Y' • T-ly c p kCS% u It i- E AS-C LAKE ST. ��?.EI.,tM��� Y t�ou�n SYSTtM �PL�a SEE Ouco%30 N1Ou'410 LAYOUT FILL. FQOM S�TCs %buAL M00%417 lbY%TEWI. WILL %E C'?EtUTiQG WkrH1L$ w•► ; % JKA- AT P CA t "t o Li "� • !. EVtET�.� \JUJ. To 'WITH VJ1T`1 CouGlli.'rE. FULL OumT% . I p•-,PQm- I-1, 19$ j 7tr. 00.1 Gee • o�. s,�, M� CtfATXY O R.A•o o � M �.1. . 5'g-1 C3-10-s1 -b . "3 Y R G A rJ , L C,LA`S 'SO v r , MW% j kA ET © 3.0 FiZo- Z.%3 To 4t6 - S.o' EA.. GRAY SILTY Shi-at.- W �-- SA' -b.5 7SLf Ck S 11.E Y CLAY - 0>ZG�u�c - Sow; �- 6.5' 0' G2AY LTY Si . CLAY �� �So►-�c: F�Nt SPUD -I�E:- Wfi TFsTl" Ar- eY- VI "ota2S - 21' oa J 0 - 2.0' 'bk. GP-b%y - t, AcJ� - SILT` CLAY ORbANtc rj&sT•I• 2.6 - 4a' GTZAy - SILTY, CLAYEY 1~ iivE SA►w --vrZ. C-0 Rom; Gp-kY SFAtNt�Y C L#,Y - O p,G ANI C - Z OF.r 4,5 - E.o bt . GRAY - S LTY (!LAY - - �QGAk3►C soMc. Ptlw So F � - W E ; ��+r,-l► tZ C. GV E L � 1 Z` - 4 -'3 - 81 BC-ACkz SILTY CLAY. C OP-T - O ZG N u tC. 2.5 - S0, (;PAY SI(.TY CLAY SoFi' - Ye.tY RMztC. SO -6.0 '�k. Gzw CLAY - SE A*'►s of Met> SAQG - l�J� L;.v6L (2? 1%4 - 4-3-81 MAY i I M�v4) C) ti A 4 O v-1 NAELL ELL M / 0 P-1 \ i E�. s% L %-- c S T. L'LfaVl4Ttow1Z �. N1, - 'iOP 1" 12a►J � Pam. Q S. E . -Pe o s. Ca EL. 100,e0 L.00 07 1C>N G�Ou rJ cL . )FRTCR t�100ETOAka; LAkC-. ` P-2 -3 CA SA 1.1 9'4 .-I p- 4 96.3 1.1. Cl 5 . '!-- 'p-< `i(,.b 0.6 9S.g SR,-\ q-I - 1.8 95. S 9 Z- . 6 95.1 p-1 15„ c�I--E-P P-5 %ARzE� ST A►.in�K G Z6 M i N r i rj c N y_ L S 10 OTt-+ TL NoL-ES ��Q« 3, ►get �E I os 3