Appendix Technical Memorandum PS-1 on Pumping Stations Condition Assessment

Transcription

1 Appendix 4-28 Technical Memorandum PS-1 on Pumping Stations Condition Assessment

2 TECHNICAL MEMORANDUM PS-1 March 8, 2013 To Copy to From Town of Falmouth, MA File; Project Team Nathan C. Weeks, P.E., BCEE J. Jefferson Gregg, P.E., BCEE Marc R. Drainville, P.E., BCEE, LEED AP Tel Subject Wastewater and Nutrient Management Services Pumping Stations Condition Assessment Job No A condition assessment was completed for the pre-1990 pumping stations that were put into service in 1985 and include: Jones Palmer Pumping Station (PS) Shivericks Pond PS Woods Hole PS Gardiner Road PS Falmouth Beach PS Inner Harbor PS The purpose of the condition assessment was to prioritize possible maintenance and repair activities and to identify the timeline for long-term improvements or replacement of these pumping stations. Similar to the evaluation of the Blacksmith Shop Road WWTF, this condition assessment does not provide a detailed evaluation of the structural, electrical, or ventilation facilities. It focuses on the main processes of the pumping stations which include the process of pumping wastewater to other locations in the collection system and ultimately to the Blacksmith Shop Road WWTF, and the support processes of flow metering, odor control, influent shredding (comminuting), and chemical feed. The condition assessment was completed through the following main steps: 1 Review of background information on the pumping station. 2 Meeting with Charlie Pires (WWTF Operator) to review issues with the collection system and pumping stations. 3 Site visit to the pumping station with Charlie Pires and Amy Lowell (Assistant Wastewater Superintendent) on December 13, 2012 to inspect each one, note problems, and document these problems with photographs. The photographs are attached as Appendices PS-1-1 through PS Summarize the findings of the condition assessment in this Technical Memorandum with short-term and long-term recommendations.

3 TM PS-1 1. JONES PALMER, SHIVERICKS POND, AND WOODS HOLE PUMPING STATIONS 1.1 Introduction These three pumping stations are grouped together because they are the larger capacity pumping stations with above-ground buildings to provide support facilities for each station. These pumping stations are equipped with flow meters and chemical feed and/or odor control facilities. 1.2 Odor Control (Air-Treatment) Facilities Odor control (air-treatment) facilities are provided for Jones Palmer and Shivericks Pond Pumping Stations. Jones Palmer has a packaged biofilter system installed in 2004 which has addressed odor complaints at that station due to odors generated in the long force main from Woods Hole. A new activated carbon facility at Shivericks Pond PS is currently (March 2013) under construction and is being implemented to address organic and sulfide odors at that location. Odor complaints have occurred mainly in the summer months and this implementation is designed to address these odors. No odor control (air-treatment) facilities are provided at the Woods Hole PS and we are not aware of any odor complaints at this location. 1.3 Hypochlorite Feed Facilities Hypochlorite feed facilities are provided at both the Jones Palmer and Woods Hole pumping stations. New storage tanks with improved hatches and access ladders have been installed at these locations to address past access and storage problems. Improved hypochlorite level indicators are still needed. The hypochlorite is pumped into the force main whenever the pumping station pumps sewerage. This chemical feed has been successful at reducing odors and corrosion in the downstream receiving facilities. The Woods Hole PS hypochlorite feed was discontinued for several months in the early 2000 s which added to concrete corrosion at the Jones Palmer influent manhole and Jones Palmer wet wells. This corrosion is evidenced by raised aggregate in the concrete surfaces of these structures due to the cement being decayed. This problem was first observed by GHD and documented in the 2008 Collection System Chemical Evaluation Report. The apparent deterioration in these areas has not worsened since 2008 due to the hypochlorite feed being resumed. No hypochlorite feed facilities are provided in the Shivericks Pond PS and there is no apparent need. 1.4 Influent Comminuting Influent comminuting facilities (shredding of influent solids) are provided at all three of these pumping stations with the following items noted: The two (2) original comminuters at the Jones Palmer PS are operational. The Operations staff have recently rebuilt one comminuter and are working on the other. They appear to be working well and no visible large solids were apparent in the wet wells. The equipment is old with much corrosion on the surface of the equipment. The original comminuters at Shivericks Pond PS were replaced with one Muffin Monster channel grinder. This works well for one channel and wet well. The other wet well is not used. 2

4 TM PS-1 The original comminuter in Woods Hole PS is still in service and appears to be working satisfactorily. The comminuter equipment is old and the surface is corroded due to age and conditions in the wet wells. Influent comminuters should be replaced when pumping stations are overhauled. 1.5 Pumping Station Pumps The pumping station pumps are all original except two pumps in Jones Palmer that were recently (2012) replaced/rebuilt, and one provided with a VFD. The pumps work well and appear to be well maintained. The current multiple-pump configuration at the stations provides adequate redundancy. Pumps should be replaced when pumping stations are overhauled. 1.6 Flow Monitoring These pumping stations were all built with ultrasonic Doppler-type flow meters used with a Venturi mounted vertically in the discharge piping before the pipe exits the station. All of these Venturi meters have been replaced by strap-on ultrasonic flow meters. Much effort has been exerted to calibrate the meters in Jones Palmer and Woods Hole pumping stations and information provided by the operators indicate that these meters are well calibrated. Operations staff indicate that the flow meter in Shivericks Pond PS is currently not reliable. These flow meters should be replaced at the time of pumping station overhaul. Often, where there is a shortage of space in a pumping station for a new meter, we recommend the placement of an inline magmeter in a vault outside the station with suitable bypass piping. Major pumping stations should be equipped with reliable flow meters to consider I/I and other flow issues in a wastewater collection area. 1.7 Major Electrical Equipment Major electrical equipment (MCC equipment and backup generator sets) are located on the top floor (ground floor) of each pumping station. This equipment appears to be well maintained. The MCC cabinets have been modified over the years as new process equipment has been added or old equipment eliminated. Comments from the operations staff indicated that electrical contractors that have worked in the Jones Palmer MCC cabinets have commented on apparent metal corrosion. 1.8 Underground Fuel Tanks The original underground fuel tanks for the backup generator sets are in the process of being removed by the Operations and Highway Department staff: The underground fuel tank for Jones Palmer PS has been removed and a new 250-gallon tank is located in the wet well side of the station in the old odor control room. The Shivericks Pond PS existing 500-gallon underground tank is still in use and is expected to be removed in the future. The underground storage tank for Woods Hole PS has recently been removed and the generator set is serviced only by its day tank. Operations staff are considering installing a new fuel tank in the station. 3

5 TM PS-1 Long-term fuel storage solutions are needed for Shivericks Pond and Woods Hole pumping stations. 1.9 Condition of Other Facilities Condition of other facilities and equipment at the Pumping Station is as follows: Jones Palmer PS: Concrete erosion in the wet wells and influent manhole due to high levels of hydrogen sulfide that are believed to have occurred when the Woods Hole PS hypochlorite feed facilities were not operational. Electrical equipment and conduit in the wet well side show corrosion which would be typical for a wet well. Electrical contractors that have worked in the MCC cabinets have indicated that there is corrosion in those cabinets. Piping, valves, and pipe supports have some corrosion and the operations staff have replaced several knife gate valves. Additional valve replacement is planned. The walls and floor of the pump room have some corrosion near the hypochlorite feed facilities. Shivericks Pond PS: Corrosion on the walls, equipment, and conduit in the wet well side is minimal for a pumping station this age. New gate valves have been installed in the pump effluent piping and appear in good condition. Other portions of this pumping station have minimal apparent corrosion (especially as compared to Jones Palmer) possibly due to smaller sulfide loads in this pumping station. Woods Hole PS: Corrosion on the walls, equipment, and conduit in the wet well side is typical of a pumping station this age. Piping is corroded particularly near the hypochlorite feed pump that appears to be leaking. Other portions of this pumping station have minimal apparent corrosion (especially as compared to Jones Palmer) possibly due to smaller sulfide loads in this pumping station. These corrosion problems should be repaired as operational funds and resources allow. All remaining corroded equipment and surfaces should be repaired or replaced at the time of pumping station overhaul Continuous Gas Monitoring Systems The continuous gas monitoring systems for these pumping stations are not working and have not worked for many years according to operations staff. The operations staff utilizes portable gas monitors when they enter 4

6 TM PS-1 the pumping stations to comply with OSHA requirements. The continuous gas monitoring systems should be repaired and made operational Summary of Condition Assessment for Jones Palmer, Shivericks Pond, and Woods Hole Pumping Stations and Recommendations for Long-Term Overhaul These pumping stations are major pumping stations that represent long-term investments in the Town s wastewater infrastructure. They are in good condition due to consistent operation and maintenance. Several repair and maintenance items have been identified that should be addressed as part of regular operations, maintenance, and repair; and the annual operation budgets should be increased/adjusted to allow for these repairs. It is understood that there is an important decision to be made regarding which repairs should be addressed as repair and maintenance, and which ones should be made as part of a systematic pumping station overhaul. Often, this decision is supported by long-term budget and Capital Improvement Planning. In 2015, these pumping stations will be 30-years old. We recommend planning for pumping station overhaul starting in the next five to ten years as wastewater management proceeds in Falmouth. Pumping station overhaul is an expensive component depending on the age and condition of the station. GHD has just completed the design of the Town of Chatham Stage Harbor Pumping Station which is the station that has provided total flow to the Chatham WWTF (similar to Jones Palmer). This is a major upgrade of this station which is over 40 years old and includes: New generator New MCCs New pumps New piping New flow meter New chemical feed The estimated cost for this pumping station upgrade is $2,000,000 (not including design and construction phase services), and overhaul of Falmouth s major pumping stations are expected to be of a similar magnitude. Consideration at each station relative to new codes and design guides for these facilities regarding electrical and other support systems will impact their costs. The approach that is taken to address these design guides and code compliance issues will affect the overhaul costs of these pumping stations. At this point in the planning process, we recommend planning for the pump station overhaul of these three pumping stations in the next five to ten years. 5

7 TM PS-1 2. INNER HARBOR, FALMOUTH BEACH, AND GARDINER ROAD PUMPING STATIONS 2.1 Introduction and Assessment These pumping stations are grouped together because they are similar designs manufactured by Boydco of East Providence, Rhode Island. They are completely underground with separate dry and wet sides. The dry side has two floor levels: the top level has the generator set and the MCC equipment, and the lower level has the pumps, bubbler system, and piping. The wet side has a grated platform above the wet well, with no other equipment (no comminuter or channels) in it. These pumping stations have no odor control or hypochlorite feed equipment and they have relatively short force mains. The pumping station pumps are all original and appear to be well maintained. Dual pumps in each pumping station are controlled by a bubbler system which provides little recording function and requires an air compressor in the dry side. The operator would like to modify these controls and standardize on a level sensing control system for each station. Major electrical equipment is located on the upper level (first level down) as discussed previously. This equipment appears to be well maintained for each station. The underground fuel storage tanks for these pumping stations are planned for removal. They have been emptied and the operators are filling the generator day tanks in the stations. A permanent, larger volume fuel storage solution is needed for these pumping stations. As identified above, these pumping stations are not equipped with influent shredding (comminuting) devices. This is not a problem for the Falmouth Beach and Gardiner Road collection areas due to the residential land use in these areas. It is a problem at the Inner Harbor area because of the commercial/hotel land use in that area. Operations staff often have to remove rags that clog the pumps at the Inner Harbor PS. This often occurs weekly. During the site visit, three options to address this issue were described: Installation of an inline grinder between the wet well and the pump. This grinder would turn on when the pump runs. Replacement of the existing pumps with grinder pumps. Installation of a shredding device in the wet well. Inner Harbor PS should be equipped with influent shredding in the future. The access point to the wet side of these pumping stations is through a primitive hatch or manhole. Watertight hatches or better seals on the existing hatches should be provided to reduce inflow to these structures especially at the Gardiner Road PS where the wet side is at a low spot on the site. These stations have minimal corrosion in the dry sides and appear to be well maintained. The Gardiner Road PS does have staining on the wells that appears to be from groundwater leakage and iron staining in the groundwater. 6

8 TM PS Summary of Condition Assessment for Inner Harbor, Falmouth, Beach, and Gardiner Road Pumping Stations and Recommendations for Long-Term Overhaul These pumping stations do not have the same level of infrastructure as the major pumping stations (Jones Palmer, Shivericks Pond, and Woods Hole) discussed previously. They are located completely underground and are located in flood-prone areas. They are generally in good condition and can be operated for several years into the future before overhaul or replacement is needed. Several repair and maintenance items have been identified that should be addressed as part of regular operations, maintenance, and repair; and the annual budgets should be increased/adjusted to allow for these repairs. Pump capacity increases have been identified and budgeted as discussed in TM S-2 as part of the preliminary design of the Lower Little Pond Watershed sewer extension. Similar to the larger pumping stations discussed earlier, there are decisions to be made regarding which repairs should be addressed as repair and maintenance, and which should be made as part of a systematic overhaul. We recommend planning for pumping station overhaul starting in five years. Overhaul of these stations is not expected to be as expensive as for the other major pumping stations. A possible approach for station overhaul would be abandonment of the pumping equipment in the dry side and installation of duplex submersible pumps in the wet well. The dry side would be overhauled for new electrical equipment. If the Town did not want to put these electrical facilities in the old dry side, they could be installed in a raised structure similar to the New Silver Beach Pumping Station. This second option may not be acceptable to the neighbors because it will obstruct the view of the adjacent water bodies and wetlands. A budget cost for an overhaul of this type would be the construction cost of the New Silver Beach Pumping Station. In summary, similar to the larger pumping stations, we recommend planning for station overhauls in five to ten years. 3. NEXT STEPS TO ADDRESS ISSUES IDENTIFIED IN THIS CONDITION ASSESSMENT We have identified several maintenance and repair items that are needed to improve performance and extend the lifetime of these pumping stations. We have also identified recommendations and approaches for pumping station overhauls in the next five to ten year periods. G:\86\15097\WP\Memos\Technical Memos\Final Submittal\Final Submittal\PS-1 Cond Assessment Memo\PS-1 Memo.docx 7

9 Appendix PS-1-1 Falmouth Beach PS Photos 1 1 All photos for all appendices were delivered to Amy Lowell on a CD and were numbered in the file name according to pump station and number.

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15 Appendix PS-1-2 Gardiner Road PS Photos 1

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22 Appendix PS-1-3 Inner Harbor PS Photos 1

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27 Appendix PS-1-4 Jones Palmer PS Photos 1

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37 Appendix PS-1-5 Shivericks Pond PS Photos 1

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44 Appendix PS-1-6 Woods Hole PS Photos 1

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