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Home My WebLink AboutNC0089290_Engineering Alternatives Analysis_20121116A 166 6W-1a Town of Mocksville Water Treatment Plant Wastewater Disposal Engineering Alternatives Analysis 11 /16/2012 Background and Contact Information The Town of Mocksville owns and operates the Hugh A. Lagle Water Treatment Plant (PWSID 02-03-010) located at 771 Sanford Avenue, Mocksville, NC, 27028 and operated by Geoff Beane, ORC (336 751-2635). The Mocksville Town Manager is Mrs. Christine Bralley (336 751-2259). The Mocksville Town Hall is located at 171 Clement St., Mocksville, NC, 27028. This report is prepared by John Grey, PE of Grey Engineering, Inc., 254 W. Water St., Mocksville, NC 27028 (336 751-2110). The Lagle Water Treatment Plant currently discharges untreated process wastewater into a tributary of Bear Creek near Sanford Avenue in Davie County, NC. Figure 1 shows the location of the water treatment plant on a USGS topographic map and the vicinity within a 1 mile radius. Raw water is drawn from Hunting Creek through three constant speed pumps and delivered for treatment to the Lagle Plant. Figures 2 and 3 provide overviews of the water treatment plant along with information on dates of construction of various plant elements. Figure 4 is a treatment process flow schematic. Wasteflows and Volumes It is important to note that, since the constant speed raw water pumps do not permit variable flow control, flow through the treatment process is controlled by allowing sediment basins to overflow into the wastewater drains as required to maintain treated water quality. Each of the wastewater treatment scenarios presented assume that the raw water pumping system and the chemical addition systems are modified to allow for variable flow through the treatment system without routinely wasting raw water through the sediment basins. Table 1 shows existing and projected service populations, demand and wasteflows. Table 1 Projected Mocksville Finished Water Demand and Wastewater Volumes 2010 2015 2020 2025 2030 2035 Residential Service Population 5,051 5,304 5,569 5,847 6140 6446 Finished Water MGD .75 .76 .78 .80 .85 .9 -Average Peak Demand MGD 1.2 1.2 1.3 1.3 1.4 1.5 Daily Backwash d 67,500 68,400 70,200 72,000 76,500 81,000, -Average Peak Daily Backwash d 36,000 36,000 39,000 39,000 42,000 45,000 Annual Backwash Flow MG 24.6 25.0 25.6 26.3 27.9 29.6 Annual Sed Basin Flow MG .5 .5 .5 .5 .6 .6 Total Annual Flow MG 25.1 25.5 26.1 26.8 28.5 30.2 Backwash Solids #/d 287 291 299 306 325 345 -Average Average Sed Basin Solids #/ r 71,000 71.000 77,000 77,000 83,000 89,000 Total D Solids #/ r 175,645 177,080 179,875 182,669 203,834 210,820 Slud eflow 3%solids / r 702,018 707,755 718,924 730,093 814,683 842,605 Town of Mocksville Page 1 of 3 Hugh A. Lagle Water Treatment Plant Some background information for Table 1 includes: From previous studies: Population projections are in accordance with NCOSBM. Backwash flows average 3% of finished flows. Backwash suspended solids average 510 mgl. Sed basin solids average 17,000 mgl. Total sed basin volume is 250,000 gallons. Sed basins are cleaned twice each year. Max filter backwash flow is 1,800 gpm. Max sed basin cleaning flow is 3,700 gpm. Alternative Evaluation Common Alternative Features Each of the alternatives investigated requires flow equalization, solids removal and chlorine control. Therefore, Figure 5 shows a pretreatment facility providing two, 50' diameter (180,000 gallons) equalization/settling tanks with solids pumping capacity and chlorine control capability. This facility is designed to receive flows from sed basin cleaning of 3,700 gpm, filter backwash of 1,800 gpm and to equalize those flows to approximately 150 gpm. The construction cost of this facility along with raw water pump station modifications is estimated to be approximately $1,700,000. Average annual operating costs for sludge removal at 0.07$/gal and electrical costs of 0.07 $/kwh are expected to be approximately $51,000 and $9,000 respectively. Surface Water Discharge This alternative will require no additional capital expense beyond the pretreatment facility and will require the least on -going operating expense. Sewer Discharge The Town pumps wastewater to the County's Cooleemee plant through a pump station permitted at 500,000 gpd and currently operating at approximately 200,000 gpd. When the pretreatment facility is discharging at 150 gpm (216,OOOgpd) the station will see a flow near its average rated capacity for an extended time. While the average annual daily flow is relatively small, the Town will need to be sensitive to surge flows during periods of extensive discharge. No additional capital expense beyond the pretreatment facility is anticipated in this analysis however, the Town would be required to pay a sewage treatment charge to Davie County currently set at $3.27/kgal. Average price increases are approximately 3% per year. This will amount to an average expense of approximately $133,000/yr for an average of 26.8 MG/yr at a price of 4.97$/1000g. Land Application Figure 6 shows soil types, flood plains and property parcels in the vicinity of the water treatment plant. An appropriate land application disposal site appears to be available in the location shown. A review of tax valuation records indicates that land values might reasonably be approximately $6,000 per acre. Application rates for the soils indicated may generally be taken as 0.2 g/sf/d based on similar project investigations elsewhere in the County. Active field area for 150 gpm at that loading rate is approximately 25 acres. Allowing for on -site storage, buffer areas and unusable areas of approximately 30%, the Town of Mocksville Page 2 of 3 Hugh A. Lagle Water Treatment Plant actual area required is approximately 36 acres. Wastewater would be pumped from the pretreatment facility to the storage pond at the application site and then pumped from the pond onto the fields. The application fields and storage pond would require monitoring and maintenance. Therefore two additional pump stations will be required along with a storage pond and distribution system. The storage pond would be sized to hold a 30 day supply of effluent and would therefore have a volume of approximately 875,000 gallons with 2 feet of freeboard. The cost of design, construction and land acquisition for the land application system is estimated to be approximately $575,000 with annual operating costs of approximately $91, 500/yr. Table 2- PVCA Summary Table Alternative Construction Cost Annual Cost PV Ann. Cost NPV Surface Discharge $1,700,000 $60,000 $695,234 $2,395,234 Sewer Discharge $1,700,000 $193,000 $2,236,335 $3,936,335 Land Application $2,530,000 $100,500 $1,164,516 1 $3,694,516 Note: A discount rate of 5.875% is used for a 20 year life cycle (PV factor = 11.5872) Conclusion Water plant wastewater discharge to the receiving stream after appropriate treatment is the most cost effective means of disposal for the Town of Mocksville by a wide margin, Town of Mocksville Page 3 of 3 Hugh A. Lagle Water Treatment Plant USGS MAP = MOCKSVILLE, N.C. 35080—H5 — `Q�� H rd on Cha _:'w"em 789 USGS MAP = COOLEEMEE, N.C. 35080—G5 2000 4000 SCALE: 1 "=2000' CONTOURS AT 10' WTP—LAGLE MILERAD 12 GREY ENGINEERING, INC. Civil Design and Surveying P.O. Box 9 Mocksville, N.C. 27025 greyengineering.com (336)751-2110 DRAWN BY: G. BULLARD PROJ. NO.: 102.195.GE DESIGN BY: DALE: 11/17/12 71 pI1 • . .. ..Rose ••`�,<, R 1'nrF: C m l Y t J �y � i r ibOT OUTFALL LOCATION LAT.: 35' 53' 22"N LONG.: 80' 34' 43"W TOWN OF MOCKSVILLE LAGLE WTP FIGURE VICINITY MAP - ONE MILE RADIUS OF 7 P \ '�\ `,� \., �\ -, yl ' ' ; , ; ; �, ► '� \err r ! ?, CONSTRUCT/ON HISTORY ' 'A\\'� \ \ \\ �\\'. �\ �'. \ �\ ? �' j 1`+ ; 1 ! ! j j y ky '1 '1 \' ,l I "-`/ I 1 1, 1946 ORIGINAL CONSTRUCTION \ ,, � ., � •, '. \ '. , •, I •. ! 1 } 1 III , � , l , , + k � ` 1966 HUNTING CREEK INTAKE RAW WATER FORCEMAIN, FILTER EXPANSION & HIGH SERVICE PUMPS J ; r i l, +� 1 ,\ \ \ , •\ _,� I I I I I 1� 11/'` -�" ' } 1 ', 1 \ `\ \ \ ! ! ! ! \ ' ! ! ; r,� •/ \ /� 1978 1.0 MG CLEARWELL _ r r i � 1 `y \ �\ \ '\` r. i 1 � I ,� '1 � 1I ' i ly jrI/ /'+_. /• OEIP -_'� � � , /! l \``\'\ \`\ _— �Ir / r/ i fit. � � ,ly 1,r�•i�1�1 /r / r/ ,/ <\ i i\ - - �J h I EIP EIR., I z 1.0 MG FINISHED WATER r �\ \ a. 1 a CLEARWELL �\ �\ x EIP EIP 1"\ ' \ �.�` LEGEND J4/29.01 DAME COUNTY GROUP HOME, INC. DS 142. PG 729 w Z w a 0 al HUNTING CREEK INTAKE RAW WATER FORCEMAIN--EI w w w EIR -- / 60' IN-- F/w -- RIGHT-OF-WAY , UP • EXISTING IRON PIPE a EIR ® EXISTING IRON 2 p 7 j f POINT ON BOUNDARY A. } x � ' 4 + r 0 50 100 % x %—x—x—X—x—x—x—%—x— / SCALE: 1"=50' SANFORD RD. ---766- w �w1w SR 1140 J4/3-2 JACK P. ALLEN & WIFE KAY W. ALLEN DV 76, PG 466 OP SIN FINISI'1ED0 TOWS _• w�w�_ �f w - TOWN OF MOCKSVILLE LAGLE WATER TREATMENT PLANT EXISTING WATER PLANT -SITE PLAN WITH HISTOR ~f SITEBEX\SITE GREY ENGINEERING, INC. FIGURE Lreyanqineertrig.com MockaWle,_N.C. (336)751-2110 10F 7 I I wv 12" wv FINISHED WATER I w w w w w w w w w w w w w I • I ��w w---"-w w w w�w r I n n n n n a" w I�,II��II��II��II��II��I WV � �_ I,rllkrllkfll�gll,gllk I JL-JL-JL JL JL-J SHED ,.0 r-- o w 7( LL —xx%— xx—x— x`X—x,x � I E I a —x—X—X—X`x—x—x—xx—x—x rE x i I I WV ■ \ I I i I 38' R --I- � I W s x 1 10'-4"H r_ \ u- >< I 1 J 100K FINISHED I WATERLi I _ i i I 0_ w \ I ---- I ~ x I J T I r-.,.-- I li ��/s L-- ------ I -- GEN PAD '9r I OFFICE L ,� \ F� I (UPSTAIRS) I 4 I < D r 1%-X-X-^X-X`X 8. 41 \ l I CO 8" 14" — w w FINISHED WATER VAULT MH 1jo" a n MH R \Q R R t -%I. f:milt R ° SETTING #3 ` 11' 13' SETTLING #2 L SETTLING #1 1 SPUTTER I ALONG WALL AT CENTER ai qh X J16 o qftz ~ U 0 -u-(n jE LMI LOCHLORINE i BLDG I a x—x x—x—x—x—x—x—x—x—x—x— RAW WATER ENTERING PLANT e FIN15HE0 WATER VAULT E � WV 44,' / 8" TOWN OF MOCKSVILLE FH LAGLE WATER TREATMENT PLANT 0 2 EXISTING WATER PLANT — ENLARGED SITE SCALE: 3/4"at'-o" MOM WV GREY ENGINEERING, INC. FIGURE SITESEX\ENLARGEL. I OVA m Z G') Z m m Z G') N N� JOO Z m n -O 70 O m (n In n 2 m D -I x 0 u la ---C----I FINISHED WATER CLEARWELL 1.0 MG LEGEND — - — FINISHED WATER - - - - INFFLUENT WASTING/SCUM SETTLING #3 CHEMICAL 112K GAL MIXER #2 \ ♦ x X\w IT / \C f I I PS�p HIGH SERVICE I ' FI #R S45KETTLING GAL #2 PUMPS I ' l�l i / FILTER _ 45K GAL SETTLING #1 A F.tF I I I CHEMICAL ADDITION I P CHLORINE, CAUSTIC, CHEMICAL MIXER 1 PHOSPHATE, FLUORIDE # I \ I /�-�--------------> --I CHEMICAL ADDITION CHLORINE, CAUSTIC, HUNTING CREEK PHOSPHATE, FLUORIDE TO TOWN'S p� PUMP STATION DISTRIBUTION 12" SYSTEM - - - - - - - - - - - -- - - --/ F 4�` —------- — 12" 0.968 MGD AVG. FLOW J 1 1 11 IV _ V \�\\ 11 iVl�/V I �1\if �_--\`\�\\`� �' � /' i OB 77,1R�88 1 It .It ' 146 10 r I / INTERIORCLEARWELL ' } BAFFLE it 1 \ `---_ -� l •.\ lipAdo �+ IsI ; o / J4 / 2801 / \ x�-- OAVIE COUNTY GROUP HONE, INC. �s x 09 142, PG 729 � x ti Ix 1 1 u x ss x ss I 11¢0 SA NF oj?D RD- 0��6 ' f ~• SCALE. 1"-60' J4/3-Y JACK P. ALLEN h WFE KAY W. ALLEN / +' OB/76, PO 466 � W 102195GE\NPOES\PLN—WP TANKS VW\NPOES 6 TOWN OF MOCKSVILLE LAGLE WATER TREATMENT PLANT 60 120 F KUF'UStU N I L VLAN Wi I H I ANKS FIGURE C GREY ENGINEERING, INC. CONTOURS AT 2' 1,450 Soils, Flood Plain and Parcels near the Mocksville Water Treatment Plant N Feet 2,900 Figure 6 SYMBOL MAP UNIT NAME & SLOPE AaA Altavista fine sandy loam, 0 to 2 percent slopes, occasionally flooded ApB Appling sandy loam, 2 to 8 percent slopes ArA Armenia loam, 0 to 2 percent slopes, frequently flooded BUB Buncombe loamy sand, 0 to 5 percent slopes, frequently flooded CeB2 Cecil sandy clay loam, 2 to 8 percent slopes, eroded ChA Chewacla loam, 0 to 2 percent slopes, frequently flooded EnB Enon fine sandy loam, 2 to 8 percent slopes EnC Enon fine sandy loam, 8 to 15 percent slopes EsC Enon fine sandy loom, 2 to 15 percent slopes! very stony GoD Gaston loam, 15 to 25 percent slopes GnB2 Gaston clay loam, 2 to 8 percent slopes, eroded GnC2 Gaston clay loam, 8 to 15 percent slopes, eroded GrB Granville gravelly sandy loam, 2 to 8 percent slopes IrB Iredell loam, 1 to 6 percent slopes MOB Masada fine sandy loam, 2 to 6 percent slopes MdB Mayodan silt loam, 2 to 8 percent slopes MdC Mayodan silt loam, 8 to 15 percent slopes MdD Mayodan silt loam, 15 to 25 percent slopes MdE Mayodan silt loam, 25 to 45 percent slopes MnB2 Mayodan silty clay loam, 2 to 8 percent slopes, eroded MnC2 Mayodon silty clay loam, 8 to 15 percent slopes, eroded MrB2 Mecklenburg clay loam, 2 to 8 percent slopes, eroded MrC2 Mecklenburg clay loam, 8 to 15 percent slopes, eroded MsB Mocksville sandy loam, 2 to 8 percent slopes MsC Mocksville sandy loam, 8 to 15 percent slopes MsD Mocksville sandy loam, 15 to 45 percent slopes PoD Pacolet sandy loam, 15 to 40 percent slopes PcB2 Pacolet sandy clay loam, 2 to 8 percent slopes, eroded PcC2 Pacolet sandy clay loam, 8 to 15 percent slopes, eroded Pt Pits, quarries RnC Rion sandy loam, 8 to 15 percent slopes RnD Rion sandy loam, 15 to 40 percent slopes RvA Riverview loam, 0 to 2 percent slopes, frequently flooded RwA Roanoke loam, 0 to 2 percent slopes, occasionally flooded SeB Sedgefield sandy loam, 1 to' 6 percent slopes Ud Udorthents, loamy Ur Urban land WeB Wedowee sandy loam, 2 to 8 percent slopes WeC Wedowee sandy loam, 8 to 15 percent slopes MAP SYMBOLS CONSIST OF A COMBINATION OF LETTERS OR LETTERS AND A NUMBER. THE FIRST CAPITAL LETTER IS THE INITIAL ONE OF THE MAP UNIT NAME. THE LOWERCASE LETTER THAT FOLLOWS SEPARATES MAP UNITS HAVING NAMES THAT BEGIN WITH THE SAME LETTER, EXCEPT THAT IT DOES NOT SEPARATE SLOPING OR ERODED PHASES. THE SECOND CAPITAL LETTER INDICATES THE CLASS OF SLOPE. SYMBOLS WITHOUT A SLOPE LETTER ARE FOR MISCELLANEOUS AREA. A FINAL NUMBER OF 2 INDICATES THAT THE SOIL IS ERODED. GREY ENGINEERING, INC. Civil Design and Surveying P.Q. Box 9 Mocksville, N.C. 27028 greyengineering.com (336)751-2110 DRAWN BY: G. BULLARD PROJ. NO.: 102.195.GE DESIGN BY: DATE: 11/17/12 SOIL—LGND TOWN OF MOCKSVILLE FIGURE DAVIE COUNTY 7 SCS SOIL MAP LEGEND OF7