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Home My WebLink AboutWQ0002284_More Information (Received)_19890104DIVISION OF ENVIRONMENTAL MANAGEMENT January 4, 1989 MEMORANDUM TO: Carolyn McCaskill, Supervisor State Engineering Review Unit Permits and Engineering Branch THROUGH: Roger K. Thorpe,/ne'Water Quality Supervisor Washington Regional Office FROM: Alton R. Hodge, Environmental% eer Washington Regional Office �`/ SUBJECT: Permit Amendment Permit No. 15514 Kinnakeet Shores Dare County Kinnakeet Shores Partnership (KSP) has submitted additional information to address the Division's concerns of the artificially elevated water table and its effect on adjacent property owners' septic systems due the proposed wastewater treatment expansion. As you know, KSP's application exceeded the maximum allowable time frame for action by the Division. KSP in the spirit of cooperation is addressing DEM's concerns. KSP has proposed an interceptor ditch to lower the water table. I have no problem with the concept of an interception structure. However this submittal does not comply with the Division's setbacks (02H.0219(j)(5)(Mj(iii)(IV) and a subsurface drainage system would appear more effective due to soil conditions and ease of maintenance. I understand the constraints of the property and situation. However, it appears that the disposal field could be oriented differently to increase distances from the wetted perimeter to the interceptor structure. If KSP can show different orientation to maximize the contested buffer, I could support a variance of the regulations. ARH:ekw ASSOCIATES Mr. Arthur Mouberry, P.E. Supervisor, P&E Unit NC Division of Environmental 512 N. Salisbury Street Raleigh, NC 27611 Management Re: Amendment to Permit No. 15514 Kinnakeet Shores Partnership Kinnakeet Shores Soundside Phase Wastewater Treatment and Disposal Dare County Bissell Associates In response to your letter to Mr Shores Partnership on September items provided in your letter in your letter questions: Breaux, Partner, Kin , we wish to address me numerical seauenc Re: Underdrain System initially proposed; we propose to utilize an open trench line sink (Interception Ditch) around the periphery of the rotary distributors. The attached Hydrologic Model performed by Russnow, Kane, and Andrews, Inc. indicates that the referenced interception ditch will effectively control the groundwater growth with no hydrologic impact beyond the 325' radius or the interception ditch, whichever is first encountered as indicated in the model. The sink drain effectively replaces the underdrain system previously submitted. Locate single family dwellings relative to wetted perimeter. The wetted perimeter is defined on attached plan sheet for the "Interception Ditch" as a 3251radius circle with its center at the center of the rotary distributor complex. From Figure 3 of the Hydrologic Model the location of the sink trench is shown at 2.5 ft. below the top of the mound elevation (8.51), or the sink elevation at 6.0 (8.5 - 2.5). By lowering the sink elevation to a minimum elevation of 3.0, or to the seasonal high water elevation, the effective wet perimeter diameter can be reduced and be actually defined by the sink trench location. The 4112 N. Croatan Hwy. Drawer 1068 Kitty Hawk, NC 27949 FAX 919-261-1760 (919) 261-3266 drawing entitled "Interceptor Ditch shows the distance between the Wetted Perimeter.(sink ditch) and the closest residential setback lot lines as 1101. Existing single family residences at the present time are mobile homes shown approximately 551, 115' and 155' from the wetted perimeter (sink trench). 3. Revised plans indicating Green Area for rotary distributor site; reference attached drawing entitled "Interception Ditch", with Green Area boundary defined. 4. Line sinks referenced in previous Hydrogeologic Report; reference attached new Hydrogologic Model and discussion in Item #1 above. 5. Previous Hydrogeologic Report indicated groundwater could effect septic tanks at mobile homes adjacent to the rotary distributors. The new Hydrogolic Model indicates the line sump will solve the problem of water from the WWTP flowing off -site. The line sump will be at or below seasonal water table and will intercept all ground water from the rotary distributors. This ground water will further be redirected to the new pond shown on the drawing titled "Interception Trench" for holding and infiltration into the soil on the opposite side of the site from the mobil homes of concern. We believe the attachments and the above explanation addresses the concerns reflected in your letter. Please contact us immediately if further information or assistance is needed in order for you to grant approval by DEM. Thank you. Sincerely, IS SSOCIATES P. Phillip u, P. E. Director of ngineering cc: John H. Gaw, J Paul Breaux Jim Mulligan Rudy Southwick Bill Reid Al Hodge Asaad Shamsi /njo AKA RUSSNOW, KANE & ANDREWS, INC. Hydrogeology Post Office Box 30653 Offices: Geology Raleigh, North Carolina 27622-0653 Raleigh, North Carolina Environmental Sciences (919) 783-8395 Newport News, Virginia Soils October 22, 19.88 Mr. Mark S. Bissell, P.E. Bissell Associates P.O. Box 1334 Kill Devil Hills N.C. 27948 Re: Hydrologic Model Kinnakeet Shores, Avon, N.C. Dear Mr. Bissell: A hydrologic analysis has .been completed of the proposed 220,000 gallon per day discharge at Kinnakeet Shores, Avon, North Carolina. Using the information gathered in our hydrogeologic analysis, dated July 1987, and a modified Darcy Equation, it is evident that the more than 1200 linear feet of ditching will accommodate significantly more than 220,000 gallons per day of dicharged effluent, based on a mound height of three feet and a distance from the center of the discharge to the line sink of 325 feet. The transmissivity of 3500 ft.2/day is based on the earlier aquifer test (Figure # 1, Site Map). We have used two analytical approaches to determine the maximum mound height. The first approach uses a modified storativity equation in order to determine the time to steady state. Using "u" equal to 0.1,the time to steady state is 5 days. Based on this time, we ran a computer model based on the Hantush Equation (Figure # 2, Mound Plot), to determine the maximum mound height. In order to be conservative, we have also modelled 10, 15 and 20 days. The maximum mound height, for twenty days, is slightly more than three feet above the seasonal high water table. For the purpose of design, the maximum mound height is three feet. The second approach uses the Glover Equation and one linear sink located 325 feet from the center of the discharge (Figure # 3, Glover Model). This model shows slightly less mound build-up and more importantly, this model shows the effect of the sink, intercepting mound growth. It can be seen that there is no mound growth beyond the sink. Therefore, by placing the Mr. Mark S. Bissell, P.E. Kinnakeet Shores October 22, 1988 Page 2 sink around the discharge growth will be stopped at r = 325 feet. More specifically, there will be no hydrologic impact on the property to the north. It is the conclusion of this analysis that the base elevation of the rotary distributors could be lowered one foot and that there will be no hydrologic impact beyond the line sinks. Please contact our office if you have any questions. Very truly yours, RUSSNOW, KANE & ANDREWS, INC. Z-0'z" -'-.7, 4c- Edwin E. Andrews III, P.G. Consulting Hydrogeologist EEA/kl enc 1. CAR �,'•�o •• BENS'••. 9 s SE AL 3 • 'sew' 7� •••..w.o'° � �,�� •• ;' atioR,,,,.•. ."'M To Pond Igh'To Pamlico Sound DATE SYM REVISION RECORD UTH on CK. nterception ditch Z TOLERANCES KI NNAKEET SHORES Itl[C[R AS NOT[DI DECIMAL SCALE DRAWN RY no f scale APPROVED ®Y FRACTIONAL TITLE t Site Plan ANGULAR DATE DRAWING HUMMER t 2 OOCT 88 Figure 1 WEC CRYSTALENE ® 10 9465 MADE IN U.S.A. ENGINEERS' STANDARD FORM 5 Y e� e e e 4 ; � X e et i$ 2 e i ®®-- I 1 -2i00 -i880 -1260 -840 -420 0 420 840 1260 1680 2100 DISTANCE X (FT) AT Y a 0 5r 4 . e e e 3 et ® 2 � e e e e e _ e e ®® e -2i00 -080 -1260 -840 -420 0 420 840 i260 i680 2100 DISTANCE Y (FT) AT X 0 PROJECT Kinnakeet Shares K s 654.5 USGPD/FT2 FILE 01-87 S .2i GROWTH OF THE MOUND LOCATION Dare County RUSSNOW KANE & ANDREWS FIGURE P. MOUND GROWTH AND DECAY ---------------------- TRIAL NUMBER 1 OF 1 . RECTANGLE LENGTH (FT): 350 RECTANGLE WIDTH (FT): 250 PERCOLATION (USGPD): 220000 WATER DEPTH (FT): 40 PERMEABILITY (USGPD/FT2): 654.5 STORAGE COEFFICIENT: .21 --------------------------------------------- ; X-VALUES ; Y-VALUES TIME ; (FT) ; (FT) ; (DAYS) ; -------------- ;-------------- ;-------------- ' G. CIO ; G. 00; 10. CIO 1 0.0 )CI ; C ). (_IC) ; 15. CI(_) ; U. UG ; U. GU ; 20. GG ; G. CIO ; 50. GG ; 10. CIO ; C ). 00; 50. CIO; 15.00 ; U. CIO ; 5C). CIC) ; 20. 00 C ). CIO ; 100. CIO ; 5. 00 C). CIO; 100. GG ; 10. CIO ; ; o. UU ; 1 C 0. C )C) ; 15. 00; G. CIO; 1 GG. CIO; 20. CIO; i 0. CIO; 200. (_I(_) ; 5.00 ; G. 00; 200. CIO; i G. 00 0.00 ; 200.00 ; 15.00 ; G. CIO; 200. CIO; 20. CIO; U. 00; 3UCI. CIO; 5.00 ; G. CIO; 3CIG. CIC) ; 10. GG G. CIO; 3GC). 00 ; 15.00 ; G. CIO ; 300. 00; 20. GG ; 50. UG ; G. C 0 ; 5. CIO 50. CIO; CI. 00; 10. C )C_I 50.00 ; CI. 00 ; 15. CIO; 50. CIO; U. 00; 20. CIO 5CI. 00 ; 50. 00; 5. CI(_) ; 50. CIO 50. CIO ; 10. CIO C ) 5. CIO ; 50. CIO; 15. CIO ; 50. 00 50. CIO; 20. 00 50. CIO ; 1 GC): -00 ; 5. C )C) ; CI 5. UU ; 1 CIU. UU ; 1 U. CIG ; 10 005G. U ; 1 UU. 00; 20. CIO; 50. 00; 200. CIO ; 5.00 ; 50. CIO; LGG. 00; 10. GC) ; 50. CIO ; 2C )C ). OC-) ; 15. 00 50. CIO ; :_UU. CIO ; i1G. GC) ; 5CI. UU ; 3CIC). CIO; 5.00 50. 00 300. 00; 10. 00; 50. CIO ; 300. 00; 15.00 ; 50.00 i .:,CIG. CIO; 20. CIO; 100. CIO ; 0.00 ; 5. CIO; 1 CIC). CIO; G. 00; 10. 00; ; 100. CIO ; 0. 00 ; 15. OC) ; 100. CICI ; C). C)C) ; 20. 00 100. )C I. 00; 50. C KJ ; S. CIC) ; i 1i_1 CI. („IO' t_I ; 15. (_)(_) i -------------- HEAD ; (FT) ------------- 4. 228C)55E+C11 4. 2 3775E+C) 1 4.294527E+0 1 4. 30G349E-i-Oi 4. 222331E+CI 1 ; 4. 267647E+G 1 4. 288997E+C) l 4. 301531E+U 1 ; 4. 2G5G37E+Cll 4. 249757E+C) l 4. 272866E+C11 4. 287321E+G 1 4. 143253E+C)l 4. i 91321E+G 1 4. 219567E+C) l 4. 238864E+C) l 4. 084487E+G1 ; 4. 1 3G426E+G 1 4. 16C1489E+C11 4. 182583E+01 4. 218761E+01 4. 265277E+C) i 4.287578E+01 ; i 4. 300695E+G 1 ; l 4. 213333E+(-)1. 4. 8594`5E+CIi 4. 282241E+C) l 4. 296G 15E+C)1 4. 196966E+C) l 4. 248314E+G 1 4.266662E+01 4. 282199E+C)1 4. 138538E+C) l i' 4. 186389E+G 1 4. 21515C)E+i_)1 4. 23505 7E+G 1 4. 082594E+G1 4. 1 27896E+G 1 4. 157936E+G1 4. 180242E+G 1 4. 193341E+C)1 4. 242635E+G 1 4. 268498E+� i 1 4. 2t3466E-E+G 1 4. 18 719E+G1 .... _.. .... ..... ... I ......... ....... _.. 77 RUSSNOW KANE & ANDREWS MOUND GROWTH AND DECAY ---------------------- TRIAL NUMBER i OF 1 . RECTANGLE LENGTH (FT): 350 PERCOLATION ( USGPD) : 2200c_ 0 PERMEABILITY (USGPD/FT2): 654.5 --------------------------------- X—VALUES ; Y—VALUES (FT) ; (FT) ; -------------- ;--------------;--- ; 200. 00 ; 200. 0� i 200. Utz ._CCU. 00 i 200. 00 ; 300. UG 200. 00 ; 300. 00 200. 00 --------------------------------- ; 300. CCU RUSSNOW KANE & ANDREWS RECTANGLE WIDTH (FT): 250 WATER DEPTH (FT): 40 STORAGE COEFFICIENT: .21 ------------------------- TIME ; HEAD (DAYS) ; (FT) ---------- '--------------' 15.00 ; 4. 165067Ei-01 ; 20. 00 ; 4. i B7663E+01 5. 00 ; 4. 060598E+01 10. GCS ; 4. 100802E+O i 15. 00 ; 4. 128656E+01 20. 00 ; 4. 150235E+01 I.) i sTvii*gcE HEA1) U 1 SGI ii-IRG ,' A L 0 N G AT UN I •r STREAM EAM P i FOOT" LENGTH (FT) (FT) (S(.. FT. /DAY) 5 DAYS 0 0.0070 24.6 63 0.0067 23.4 125 0. 0058 20. 2 250 0.0034 11.8 500 0.0014 5.1 1000 0.0000 0.0 TOTAL DISCHARGE = +1.64581E+04 CUBIC FT./DAY 10 DAYS 0 0.0081 28.3 63 0.0077 27.1 125 0. 0068 `,.. 6 250 0.0044 15.4 500 0.0015 5.3 1000 0.0002 0.8 2000 0.0000 0.0 TOTAL DISCHARGE = +2.05641E+04 CUBIC FT./DAY 15 DAYS 0 0.0085 29.8 63 0.0081 28.5 115 0.0072 25.2 250 0.0048 16.7 500 0.0018 6.4 1000 0.0011 4. 0 2000 0.0000 0.0 TOTAL DISCHARGE = +2.71326E+04 CUBIC FT./DAY 20 DAYS 0 0.0087 30.5 63 0.0084 25.3 125 0.0074 25.9 250 0.0050 17.4 500 0.0020 7.0 1000 0.0000 0.0 TOTAL DISCHARGE = +2.21685E+04 CUBIC FT./DAY RECHARGE. RATE _ . 37 FT/DAY TRANSMISSIVITY = 3510 SQ.FT/DAY SPECIFIC YIELD = .21 PEGINVING TIME = 5 DAYS FINAL TIME _ 20 DAYS TIME INCREMENT = 5 DAYS TIME OF CUT OFF = 20 DAYS BEGINNING DISTANCE = u FT FINAL DISTANCE = 400 FT DISTANCE INCREMENT = 100 FT DEPTH = 5 FT WIDTH = 250 FT LENGTH = 350 FT ANGLE = 0 DEGREES STREAM DISTANCE = 325 FEET MOUND PROFILE YES STREAM.DISCHARGE ,YES TIME DISTANCE HEIGHT (DAYS) (FT) (FT) 5 0 1.975 5 100 1.679 5 100 1.696 5 200 G. 900 5 200 1.313 5 300 0.177 5 300 0.803 5 400 0.541 10 U 2.226 10 100 1.943 10 100 2.126 10 200 1.079 10 200 1.552 10 300 0.203 10 300 1.041 10 325 0. 000 10 400 0.791 15 0 2.412 15 100 2.028 15 1 w.l 2.337 15 200 1.128 15 200 1.688 15 300 0.213 15 300 1.174 15 325 G. 000 15 400 0. 84 5 20 0 2. 475 20 100 2.074 20 100 2.415 20 200 1.154 20 200 1.864 20 300 0.218 20 300 1. 358 20 325 0.000 20 400 0.928 GTE WM REVISION RECORD UTH BASTM 5 3. Cm.5 TIME DISTANCE 20 400 u HEIGHT fi T .9 TOLERANCES wx"wr"mo"ol KINNAKEET SHORES DECIMAL SCALE . DRAWN BY JAA APPROVED BY f FRACTIONAL TITLE t Predicted Mound Height - RECHARGE ANGULAR DATE DRAWING NUMBER t 20 OCT 88 Figure 3 Y CRYSTALENE ® 10 9465 MADE IN U.S.A. E ENGINEERS' STANDARD FORM RUSSNUW KANE & ANDREWS MOUND GROWTH AND DECAY ---------------------- TRIAL NUMBER 1 OF 1 . RECTANGLE LENGTH (FT): 350 RECTANGLE WIDTH (FT): 250 PERCOLATION ( USGPD) : 220c'►0o WATER DEPTH (FT): 40 PERMEABILITY (USGPD/FT2): 654.5 STORAGE COEFFICIENT: .21 ----------------------------------------------------------- 1 X—VALUES ; Y—VALUES ; TIME HEAD i (FT) i (FT) ; (DAYS) i (FT) ; -------------- ;-------------- f-------------- ;--------------' 200. 00 ; Ei 0. 00 i 15. 00 ; 4. 165067E+O 1 200. 00 ; 200. CMG ; 20. 00 1 4. 18766 E+01 1 200. 00 ; 300. 00 i 5. 00 1 4. 060598E+0 1 1 i 200. GU ; 300. Grp ; 10. 00 ; 4. 1 GUAG:_E+C> 1 ; 200. 00 3 o. 00 15. 00 4. 1 `8656E+01 i 200. 00 f 300. 00 ; 20. CMG ; 4. 150235E+01 ; RUSSNOW KANE & ANDREWS