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030 ( '-. PAGGI,MARTIN &DELBENELLP Consulting Engineers & Land Surveyors uS6 .' 56 Main Street Poughkeepsie, New York 12601 914-471-7898 914-471-0905 (FAX) RECEIVED AUs 2 ~ 2000 ELAINE S rOWN NOWDEN CLf2~K August 22, 2000 Town Board Town of Wappinger P.O. Box 324 Wappingers Fal/s, New York 12590 Attention: Constance O. Smith, Supervisor Reference: Wappinger Sewer Transmission/Treatment Improvement/Phase 3A Tri-Municipal Sewer Construction Dear Supervisor Smith & Board Members: A meeting was held at the Tri-Municipal Sewer Commission on August 22nd, 2000. Dr. InderJit Kumar of Eustance and Horowitz gave a presentation regarding the finished Tri-Municipal plans for the Improvement, and a handout was distributed to attendees by Dr. Kumar. I have included a copy of this handout with this correspondence. In the presentation Dr. Kumar enumerated and explained the changes that were made as the plans differ from the Map, Plan and Report. More important, Dr. Kumar reported that, in his opinion, there would be no additional cost(s) associated with the changes, as there also have been some deletions of certain items that were included in the Map, Plan and Report. He felt that the additions and the deletions would balance out. If there are any questions or comments, please do not hesitate to contact this office. vervV@ ~ E. Paggi, Jr., P.E. JEP:law Enclosure cc: Hon. Vincent Bettina, Councilman w/enclosure Hon. Joseph Paoloni, Councilman w/enclosure Hon. Joseph Ruggiero, Councilman w/enclosure Hon. Robert Valdati, Councilman w/enclosure Hon. Elaine Snowden, Councilman w/enclosure Albert P. Roberts, Esq. w/enclosure Michael Tremper w/enclosure Joseph E. Paggi, Jr., P.E. Ernst Martin, Jr., PE., L.S. Chales R. Del Bene, Jr., rEo CONSULTING ENGINEERS . LAND PLANNERS . LAND SURVEYORS I . (z.- '~,. 1<\ r~ ,,,,~~_:- lf~OO '-'~" I ~:~.r,j;<f:';".).,l~.....~.~ ~'\ j,.,' ~ . ;r'-- ~~h.~~-''':''lfj,,;' ~:: m~"'.~..... ~~-':':''''':;::'';:'-~-'~ EUSTANCE &- HOROW/T~ P.C. Synopsis Proposed sewer Project - Phase 3 (0.375 MGD Increase) T ri-Municipal Sewer Commission August 22, 2000 Pump Station - Contract #1 Existing Conditions Pump Station has three pumps as follows: 1. 2. 3. Pump #1 Pump #2 Pump #3 200 HP 200 HP 75 HP All the above pumps discharge the through a single 10-inch 1.0. ductile iron force main. Proposed A separate force main is proposed for Phase 3A. We have provided a valve so that each of the two 200 HP pumps can utilize their own force main. Pump #1 pumps through the existing 10- inch force main and pumps 1,850 to 2,250 gpm. Pump #2 pumps through the proposed 16- inch 13.488 I/O force main and pumps 2,300 to 2,550 gpm. Pump #3 (75 HP) pumps through the proposed 6-inch 0.0. force main and pumps 1,100 gpm. The pump station will pump between 1,100 gpm and 4,800 gpm, maximum pumped (no trim impeller), 4,800 gpm. If the impeller for pump #2 is trimmed to 15.5 inches and a 100 HP motor is installed on pump #3, we could get 1,500 gpm from the 100 HP, 2,250 gpm from pump #1 and 3,050 gpm from pump #2. The pump station will pump between 1,500 and 5,300 gpm. Do we need the increased capacity? I am not sure. For the time being, I will not do anything. However, if and when we have to repair pump #2, we should consider trimming the impeller. If we have to replace the 75 HP motor, we should replace it with a 100 HP. This will involve a new variable frequency drive also. However, until this is done, the valve on the 16"-inch pipe will have to be throttled such that the motors are not overloaded. Surge Relief Valve Due to the piping changes proposed, there will be no surge protection for pump #1. We have, therefore, provided a new surge relief valve for pump #1. P.O. BOX 42 CIRCLEVILLE, NY 10919 914-361-4541 FAX 914-361-1045 IlEII ~ . Existing Generator -~ The existing generator was installe~986. When Phases I and II were completed in 1996, larger pumps were installed, but ~ was not upgraded. The two 200 HP pumps will be able to pump 4,800 gpm of sewage only when electric power is available. The generator cannot operate the two 200 HP pumps simultaneously. However, it can operate one 200 HP and one 75 HP pump. These two pumps can pump 3,350 gpm. Our future project should be to install an additional generator such that the two 200 HP pumps can operate simultaneously. If pump #1 goes out of order and needs repairs, the pump station can pump a maximum of 2,550 gpm. If pump #2 fails, the pump station can pump 1,100, 2,250 or 3,350 gpm. Flow Regulator Since the flow to the pump station is increased by 0.375 mgd, average and 1.05 mgd peak, the flow regulator has to be modified. There is an orifice in the flow regulator, which will be replaced with a larger orifice. The 8' x 8' regulator pit is covered with a steel plate at this time. To enter the pit, two or three persons are needed to remove the plate. It is a safety hazard. We have covered the pit with a concrete slab and provided an aluminum hatch and access ladder. Electrical Controls The sequence of operation of the pumps will be changed due to the piping changes. This will require modification to existing electrical controls. ~ Flow Meters There is one existing flow meter, which reads only up to 2,000 gpm. When the surge tanks are full and the pump pumps over 2,000 gpm, the flow meter is pegged at 2,000 gpm and there is no indication how much sewage is being pumped. This meter will be modified to read up to 4,000 gpm. A new meter is provide&On the new for(i5ain. This met~ill read up to 4,000 gpm. Items such as surge relief valves, electrical controls, regulator pit slab and ladder were not included in the map, plan and report (MPR). The modification to the existing flo~eter was also not included in the MPR. ~ {1Jo\ 1\ ~ COS-t4> 2 -= . Force Main - Contract #2 Existing Conditions 1. Ten-inch (10") ductile iron (0.1.) force main from pump station to Sunny Crest Drive/Jordan Street, 2,180 feet. 2. Twelve-inch (12") PVC gravity sewer from Jordan Street to Channingville Road, 975 feet. 3. Fifteen-inch (15") and eighteen inch (18") PVC gravity sewer from Channingville Road to inside Bowdoin Park, 3,075 feet. 4. Ten-inch (1 a") 0.1. depressed sewer from inside Bowdoin Park to the plant inlet sewer, 1,840 feet. 5. Thirty-inch (30") plant inlet sewer to the wastewater treatment facility, 3,270 feet. Proposed project as per the plans: 1. Ten-inch (1 a") 0.1. force main from the pump station to the meter pit outside the pump station, then 16-inch 0.0. high density polyethylene (HOPE) pipe horizontal drilling under Wappingers Creek and installation of 16-inch 0.0. HOPE force main up to Sunny Crest Drive/Jordan Street. 2. Eighteen-inch (18") PVC gravity sewer on Jordan Street to Channingville Road. 3. Eighteen-inch (18") PVC gravity sewer on Channingville Road and from Channingville Road to inside Bowdoin Park. 4. Twelve-inch (12") 0.1. or sixteen-inch (16") 0.0. HOPE depressed sewer from inside Bowdoin Park to the plant inlet sewer. The following items differ from the map, plan and report (MPR): 1. Force main size from the pump station changed from 12-inch 1.0. ductile iron pipe to 16-inch 0.0. (13.488" 1.0.) HOPE pipe. For horizontal drilling, HOPE pipe is preferred because of its lightweight. 2. Horizontal Drilling under Wappingers Creek in place of direct bury in the creek bed. 3 3. No sewer pipe on Jordan Street; paralleling 12-inch gravity sewer was proposed in MPR. The plans proposed 18-inch PYC gravity sewer in Jordan Street. Due to the increased flow from the pump station, the existing 12-inch pipe is not adequate to handle 4,800 gpm. II 4. MPR calls for two new 12-inch 0.1. pipe depressed sewers. The plans show only one new 12-inch 0.1. or 16-inch 0.0. HOPE depressed sewer. We feel you do not need two new pipes. We will have two pipes starting from the pump station, all the way to the 30-inch plant inlet sewer. There is no need for a three pipe depressed sewer. The New York State Environmental Facilities Corporation (NYSEFC) will be approving the plans with one new depressed sewer pipe. 4 ,. Contracts 3 and 4 Existing Units 1. Bar screen, with motorized screenings removal 2. Comminutor 3. PIST A grit chamber 4. Two Parshall Flume and meters 5. Four 35-foot diameter primary clarifiers 6. Four 2 compartment aeration tanks with 15 HP aerators (8 total) 7. Four 35-foot diameter secondary clarifiers 8. Chlorine contact tank 9. Outfall sewer 10. Four sludge holding tanks, two covered 11. Belt filter press in Operation and Maintenance building 12. Compost building with six 15 HP blowers Proposed Units 1. Headworks Building/Bar Screen The map, plan and report (MPR) calls for one comminutor, one grit chamber and a Parshall Flume. The proposed plans show auger monster type comminutor and a grit chamber. To provide auger monster type comminutor, the existing channel walls and stairs have to be cut. We had planned a muffin monster type comminutor in the MPR. The operators (STE) suggested that we should take the grindings out as they are ground in the comminutor instead of dealing with them in primary clarifiers and sludge train. Therefore, an auger monster has been provided, which will be twice as much in cost to install (equipment and installation) as muffin monster. 2. Grit Chamber One grit chamber is provided in accordance with the MPR. 5 No new Parshall Flume is provided because we were able to divert the flow to the existing channels by taking the non-working, old comminutor out. 3. Aeration Tanks The MPR calls for replacing four existing 15 HP mechanical aerators with new 30 HP aerators. We have again checked our calculations and find that 25 HP aerator will be more than adequate. So the plans show replacing 15 HP aerators with 25 HP aerators. 4 Secondary Clarifier One 35-foot diameter secondary clarifier is provided in accordance with the MPR. 5. Plant Piping There is a 16-inch pipe between the clarifier outlet chamber and the UV channel and from the UV channel to the chlorine contact tank and outfall manhole in front of the operation and maintenance (O&M) building. The map, plan and report had no provisions for changing this pipe. However, with the Village pump station pumping up to 4,800 gpm, the 16-inch pipe is not adequate and has to be changed. The proposed plans show new 24-inch pipe replacing the 16-inch pipe where possible. 6. Chlorine Contact Tank The map. plan and report calls for a 12,000 gallon chlorine contact tank. After the MPR was finalized, it was observed that the plant has problems meeting disinfection requirements. We have, therefore, provided a chlorine contact tank with a capacity of 28,000 gallons. This is the largest chlorine contact tank we could fit in the available space. 7. Sludge Holding Tank Covers Two of the sludge holding tanks, which are open at present will be provided with dome covers. Also, an odor control system will be provided for these two sludge holding tanks. This is as per the MPR. 8. Compost Blowers Three compost blowers were included in the MPR. At the suggestion of operators, these blowers will be provided to supplement air in the three existing headers. 9. Electrical equipment for all the new units will be provided. T msc-swr proj/eng 6 II ..~ .~~ ,'f i~ 'I f)", f -'Ii"\ ,\] /' y...Jl' ~"