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Home My WebLink About1974-BOH-rpt.pdf 1 1 REPORT RELATIVE TO l FLUORIDATION 1 LEXINGTON, MASSACHUSETTS 1 JULY, 1970 I 1 [i ��ZH OFAtgs;� /...;,e‘..\.‘ ELIAS bG (g COONEY t E) NO. 21769 0 it F, s'f F' 4� SL \FSS/4NAL WHITMAN & HOWARD, INC IJ ENGINEERS AND ARCHITECTS 89 Broad Street Boston, Mass j LJ I L. I � ofttellied by YAt'.IUC G2r-19.77?; 1-1 1 EST 1869— INC. 1924 W&H I i C. Roger Pearson, President ASSOCIATES C R.Wickerson,Treasurer WHITMAN & H O WA R D INC I-; Paul F Howard, Chairman f George G. Berlow I Jr. Gerald T Carey Paul C. Bucknam,J Engineers and Architects Anthony Chiaravelotti Brewster W. Fuller Elias A.Cooney Myles F Howard 89 BROAD STREET BOSTON, MASS. 02110 TEL. (617) 426-6400 Robert E. Crawford Robert T. Jones Roger P Disken Charles G. Ellis Frederick D.A King,Jr. Ernest H. Fagerstrom James T.McDonough George A.Howland,III Howard R. Perkins,Manager Laurence T Kraynick C. Glover Thompson,Arch Officer July 13/ 19 7 Kenneth A. Lucas Edward R. Mayer Mr William L Cosgrove, Chairman Lexington Board of Health Town Hall Lexington, Massachusetts 02173 Re Fluoridation of Water Supply Dear Dr Cosgrove In accordance with our agreement with the Board dated April 3, 1970, we are pleased to submit the following pre- liminary report on the methods, costs and operating procedures for the fluoridation of the Lexington water Lexington is supplied with water from the Metropolitan District Commission (M D C ) and is fed at four remote points At each of these locations the quantity of water is metered by the M.D C and the Town of Lexington is billed for the water based on these readings At the present time, the average daily water consumption is in excess of 5 , 000 ,000 gallons per day In order to effectively fluoridate the water, the chemical must be injected at each of the four locations where the water enters the Town At each metering location the Town owns an adjacent I lJetz /0/4 Teat a UanLtnt[atta c etvtce r1 concrete vault which presently houses chemical feed equipment 1 for injecting sodium hexametaphosphate into the water to control corrosion and to sequester iron and manganese and, thereby, prevent red water problems The size of these subsurface vaults averages 290 cubic feet (6 ft x 6 ft x 8 ft ) The vaults are located under the sidewalks on Summer Street at the Arlington Town line, on Watertown Street near the Route 2 crossing, on Waltham Street near Route 2 and on Massachusetts rl Avenue near the Arlington line Three of the vaults flood periodically with water Although there are different chemicals and feeding methods available for fluoridating water two alternatives , sodium fluoride and sodium silicofluoride, are feasible for Lexington Llsince these chemicals are easily obtained, relatively safe and the feeding equipment reliable 11 Sodium fluoride chemical is more expensive to feed than is l sodium silicofluoride but the equipment to feed sodium fluoride is considerably cheaper For larger installations sodium silico- nfluoride is more economical (chemical costs lower) while in smaller II installations sodium fluoride is usually more economical Since this installation would be moderately sized, the choice of feeding it methods becomes not only a matter of economics but convenience and handling as well The two alternates will be described Jseparately -2- Ui f SODIUM FLUORIDE ALTERNATE I Sodium fluoride is a granular crystal that is easy to handle and presents little or no health danger from dust A ` 4% saturated solution of the chemical is prepared and this ri solution is then pumped into the water system, the entire 1 process being automatic The operator only has to periodically add sodium fluoride crystals to the 50 gallon saturator tank 1 Within the four existing vaults there is enough room to j house sodium fluoride equipment along with the sodium hexa- 1 metaphosphate equipment The vaults themselves , must be water ` tight to insure the integrity of the chemical system To do this , a waterproofing compound would be applied to the walls, 1 new hatches installed, new concrete floors added and high capacity sump pumps installed Once this has been done, the fluoride equipment would be installed along with new phosphate feed equipment The chemical pumps could be paced from the existing -� M.D C water meters located adjacent to the vaults and the chemicals fed into the main using the existing lines A typical floor plan of one of the vaults may be seen in Figure 1 1 On Table 1 are listed the itemized costs for feeding sodium fluoride from the existing vaults The total project cost would L1 be $50 ,000 and the cost for feeding the fluoride would be about `� $5000 per year Although this method would have the least initial costs , other factors must be considered L -3- I TO DISTRIBUTION SYSTEM-›* ELECTRICAL DRAIN WALL MOUNTED PHOSPHATE ELECT PUMP— WATER SUPPLY , 1 - 'I ' - lia. , al,g, 1 . ) .'t, , ____, --------,icEr----- ' \1/41 SUMP PUMP---CA, 1 ti SODIUM FLU RIDE 1 �� ATURA - r' V n \b - - tPHOSPHATEKS ; it, Ira. , WALLSIMOUNTEDLLRPUMP Ago �� it EXISTING HATCH Li I ELECTRIC PACING SIGNAL FOR PUMP ° [ 1 TO E FROM M.D.C. H I , i EXISTING CONCRETE VAULT 1 ! 1 H TYPICAL SODIUM FLUORIDE RSTALLATION ULEXINGTON, VASS. SCAT E 14= %„ Li WHITMAN & HOWARD, INC. PLATE I ENGINEERS & ARCHITECTS BOSTON, MASS. Lexington, Mass Table 1 COST ESTIMATE FOR INSTALLING SODIUM FLUORIDE EQUIPMENT IN FOUR EXISTING VAULTS. I ALTERNATE I 1. For waterproofing and reconditioning the four existing vaults including, waterproofing compounds, new concrete floors, 70 gallon per minute sump i pump, new watertight hatch covers and all incidentals, labor, tools, and equipment $12,000 11 2. For furnishing and installing sodium fluoride equipment including transmitters, chemical pumps, two saturators per vault, electrical controls, safety equipment, test apparatus, unit heaters etc. 24,000 3 For furnishing and installing new sodium hexametaphosphate feed equipment including new pumps, two 55 gallon barrels per vault etc 4,000 LITOTAL CONSTRUCTION COST $40,000 Contingencies & Engineering 10,000 TOTAL PROJECT COST $50,000 -5- Li U r Since the vaults are below ground, the bags of fluoride (100 lb ) would have to be carried down steep stairs The vaults are l relatively small and maintenance and record keeping would be II difficult No room for storage would be available in the vaults l so the operator would have to transport the fluoride to each location from a central storage And, of course, the possibility always exists that the vaults could lose their watertight integrity As a routine safety precaution, a second man should be present whenever the first enters a vault Based on financing this alternate over a 20 year period, Il the annual cost would be about $3800 not including operation and chemical costs SODIUM SILICOFLUORIDE ALTERNATE II An alternate to feeding sodium fluoride using saturators would be to feed sodium silicofluoride using dry feeders and LIdissolvers Sodium silicofluoride is a powder which is fed in a dissolver from a bag loading hopper Water is automatically LIadded to the dissolver so that the strength of the solution is II always constant (0 2%) Using a proportional feed chemical pump the solution is fed from the dissolver into the water system -6- LI I r The equipment necessary to feed silicofluoride is 11 relatively large and is more expensive than the equipment Fl to feed sodium fluoride but sodium silicofluoride is a less expensive chemical and consequently costs less to feed The I vaults previously mentioned, are not large enough to accommodate silicofluoride equipment i i In order to use silicofluoride new above-ground structures i } would have to be built in three locations, at Summer Street near the Arlington Line, at Watertown Street near the Route 2 crossing and at Waltham Street near Concord Avenue At the fourth location, ) 1 Massachusetts Avenue near the Arlington line, no room is available for an above-ground structure and therefore, the present vault will have to be reconditioned and the fluoride will have to be fed using saturators and sodium fluoride as discussed under I Alternate I jI A typical sodium silicofluoride station is shown in Figure 2 and 3 Within each building there would be proportional feed pumps, helix feeder, dissolver, bag loading hopper, valves , piping, electrical equipment, heater, file, desk, phosphate feed equip- ment and storage for both fluoride and sodium hexametaphosphate The total project cost for Alternate II including three new silicofluoride installations and one sodium fluoride in- IF ] stallation in the vault on Massachusetts Avenue would be $89 ,500 , LJ while the cost for the chemicals alone will be $2800/year !J -7- LI 9 Lexington, Mass Table 2 COST ESTIMATE FOR INSTALLING SODIUM 'SILI'COFL'UORIDE EQUIPMENT IN NEW 'ABOVE_GROUND"STRUCTURES ALTERNATE II ri 1. For constructing three new above- ground structures to house new sodium silicofluoride equipment including concrete, brick & block masonry, excavation, fill, labor, tools, materials etc. $30,000 i 2 For waterproofing and reconditioning [ the existing vault on Massachusetts Avenue near the Arlington Line to house sodium fluoride equipment, including waterproofing compounds, II1 new concrete floor, 70 gallon per minute sump pump, new watertight hatch cover and all incidentals 3 ,000 3. For furnishing and installing new 11 sodium silicofluoride equipment in the structures of Item #1 complete including piping and 27,000 electrical work ll4. For furnishing and installing new sodium fluoride feed equipment in the renovated vault given in Item 2. 6,000 5. For furnishing and installing new sodium hexametaphosphate feed equipment including new pumps, barrels etc. in each of Ij the four locations 4,000 �� $70 ,000 Contingencies & Engineering 17,500 TOTAL PROJECT COST $89,500 -8- H { Lexington, Mass. i 1 Table 3. CHEMICAL COSTS FOR ALTERNATES I & II 11 1. Chemical cost for feeding Sodium Fluoride into system at rate of 1 0 mg/L of Fluoride ion as r� described as Alternate I based $ 13 60/day on average 1970 water consumption or $ 50Q0%/year tii 2. Chemical costs for feeding Sodium silicofluoride in three installa- i 11 tions and sodium fluoride in one installation at rate of 1.0 mg/L fluoride ion as described as I_l Alternate II based on average $ 7 68/day 1 1970 water consumption or $ 2800/year i 11 3. Chemical cost to feed 2 0 mg/L of Sodium hexametaphosphate as is now being practiced in � iLexington based on average 1970 $ 10 82/day water consumption or $ 4000/year I_Jll l LI LI -9- d Hi A t ri Il' - 6 .. r 9 .1 . 9 ' v iI I PROPORTIONING PUMP -7 1�\ `\-\\\�`��\S\ \\ St \i - iii`\s�-• t �\ ko n K) \' ,:xxXXxxxxxxxxxxyL xl///X/'X':✓Y� \ F \ jl\ WALL C - I / MOUNTED \ :• ELECTRIC . PHOSPHATE \ HEATER FAIl , PUMP \ \ ~ 11, PHOSPHATE TANKS by SCALE pmT�� FEEDER -m� WSODIUM+SILICOFLUORIDE DISSOLVERcriBAGS _ LI 7 ELECTRICAL PANEL +—STORAGE ( l \ • PLATFORM J � i DESK \ • PHOSPHATE (l \ BAGS \ ' \ •, \ p FILE 4' H4.\ CABINET 4` \ xx)cxxk 0cri?,,r XxXXXX)XXX • A_AR s• \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\` `D I HSCALE 3/8" = I.- 0" 1 LI TYPICAL SODIUM SILICOFLUORIDE INSTALLATION 1 LEXINGTON MASS 1] WHITMAN C HOWARD INC . I ENGINEERS and ARCHITECTS BOSTON MASS . Li FIGURE 2 I If the construction cost of $70 ,000 is bonded over a 20-year period, the annual cost not including chemicals would be about r $6700 A cost comparison between Alternates I and II can now be made ALTERNATE I ALTERNATE II Annual Capital Cost to 'orroT* coney 1 for initial con- ,truction $3800 $6700 Annual Cost for 1 Fluoride 0500n $2800 Total Annual Cost* ^0200 $9500 The difference in annual cost is t7n8 This difference must be balanced against the convenience of above-ground structures, the added safety, ease of maintenance, on-site storage, record keeping etc that would be available with new structures to house the equipment One additional factor beyond the scope of this report is the land takings that would be necessary for new structures L * Does not include labor or land costs -11- rl I r \ / Y iii ""`� ; ‘, i 1 r ®� _ i ‘ - N. ,,. ,... _,_,_.,________.,..._...__..._.._..___..__....________________,...-., 1 '--. '1-ii:0-11H---- 1 , '1 rek,43„--, f , , . -a -________________,,i k,,,,\\,\, r------7 ,0,____-_,Tht ______ ,, \k li � � aar � a� �I III LH°LJ��.� 1 �� jl c 0‘ :i ril t. v i...-----------------------"--t—m- C �� TYPICAL SODIUM SILICOFLUORIDE STATION oJM - NOT TO SCALE co it I ) Once the 'initial capital expenditure has been repaid a comparison between the Alternates should be made based on 11.1 chemical costs alone In fact, six years after the municipal bonds to finance the project have been retired, the cheaper cost of sodium silicofluoride has offset the higher equipment costs and the two Alternates become economically equal It is our recommendation that should Lexington proceed it to fluoridate the water, Alternate II using sodium silico- fluoride should be chosen based on long range costs , ease of handling, safety and maintenance OPERATION OF EQUIPMENT 1 Sodium fluoride, a granular chemical, is purchased in 100 pound bags Each bag would last approximately three L1 days per installation at average flow rates At maximum and peak days fluoride would have to be added perhaps every day The chemical is free-flowing and relatively safe to handle if routine safety precautions are observed The saturator itself jj is a 50 gallons plastic barrel in which the fluoride is added LJ in excess resulting in a saturated solution of 4% strength This constant strength solution is then pumped from the sat- urator to the main Other than adding the chemical routine L maintenance would be required to keep the equipment in top operating condition Once every two or three months, the saturators would have to be drained and thoroughly cleaned -13- a 1 2 Sodium silicofluoride is a free-flowing powder that r is slightly more dangerous to handle than sodium fluoride since, as a powder it can form a fluoride dust The chemical is shipped in 100 pound bags and each bag is hand loaded into the hopper From the hopper a helix screw feeds the fluoride into the dissolver The rate of chemical feed and the make-up water it is continuously and automatically controlled to insure a t con- stant strength solution in the dissolver From the dissolver, a proportional pump discharges the solution into the water main One bag of silicofluoride could last anywhere from 1 1/2 to 5 days depending on the rate of water consumption Il 3 In both Alternates new sodium hexametaphosphate feed equipment is proposed to replace the equipment now in use J This is necessary because of space and to couple the pacing Iequipment to all the pumps Since the M.D C water for Lexington flows through Arlington, the possibility exists that a joint venture be- tween the two municipalities could prove beneficial to each For this reason, we recommend that a conference be held with Arlington, representatives of this office and with the M D C to ascertain the feasibility of this I l1 -14- U J I ri r Petition will have to be made to the M.D C to obtain permission to use the existing water meters to pace the fluoride pumps 1 We shall be pleased to meet with the Board at any time to discuss this report rl Respectfully submitted, WHITMAN & HOWARD, INC 11 X7. /ef/e/vrey Steven Medlar SM/ed Approved By ��.�F-. E A. Cooney, P E -NOF MAssyC\ } I ELIAS t' COON EY 0 NO. 21769 L \SeorgA cc'- , J -15- Li