Water Project

Monsoon Consultants (Monsoon) was retained by the City of Perry (Perry), to provide recommendations for upgrading their municipal water treatment system. Perry's foremost priority is to resolve Consent Order Case No.05-002A issued on March 29, 2007, by the Oklahoma Department of Environmental Quality (ODEQ) regarding disinfection by-products and TOC levels exceeding allowable standards. The City proposes to upgrade the existing water treatment system to reduce the disinfection by-products and TOC levels and bring the municipal public water system into compliance with current regulations.

Perry is centrally located in Oklahoma with direct access from Interstate 35 and U.S. 412. The community is located approximately 60 miles due north of Oklahoma City and serves as the county seat for Noble County. Perry has an estimated population of 5,042 (U.s. Census 2007) and includes approximately 2,200 households with an average of 2.31 persons per household. Perry owns and operates their own public water system which derives its water supply from two (2) sources which include Lake McMurtry and Lake Perry. Untreated water from each of these sources is delivered to the Perry Water Treatment Plant (PWTP) via pipelines where it undergoes conventional lime softening, flocculation, sedimentation. filtration and disinfection prior to being pumped into the distribution system.

Perry intends to restore the water system to a level that meets the Oklahoma Department of Environmental Quality (ODEQ) requirements through the implementation of physical improvements described in the following sections of this report. This report will serve to address available alternatives and provide recommended solutions in order for Perry to apply for public grant funding.

ALTERNATIVES

Perry has expended significant resources, including labor and expense, over the past few years attempting to reach regulatory compliance through optimization of their treatment operations. The expertise of both the ODEQ and 3rd ^{part consultants has been solicited and improvements to the treated water quality have been achieved. Even with these efforts and the attained improvements, it has become clear that physical improvements to the water treatment system must be implemented to achieve regulatory compliance. Based on the preliminary engineering analysis summarized herein, Monsoon believes that the following technically feasible improvements to Perry WTP appropriate and offer the best available solution afforded Perry to achieve regulatory compliance and meet the terms of Consent Order Case No. 05-002A.}

^{Flocculation I Sedimentation Basin Enclosure:}

^{The excessive algal growth within the exposed flocculation / sedimentation basins is problematic and has proven impossible to manage chemically or through modified plant operations. The algal growth results in elevated TOC levels, which rise dramatically during the warm summer months, when sunshine and warmer temperatures create optimal conditions for algal propagation. Based on our engineering analysis, it was determined that the preferred alternative to mitigate this problem will be the construction of an enclosure around the flocculation / sedimentation basins. The proposed enclosure would have a footprint of approximately 150ft x 75ft, with a height to be consistent with the existing chemical treatment and control buildings. The proposed enclosure will consist of a metal building with roof and sides and would connect to the existing chemical treatment building to the south and the control/filter building to the north. The building will incorporate steel roof trusses to permit spanning the flocculation / sedimentation basins and utilize a perimeter continuous footing with spread footing / or shallow concrete shaft column foundations. The enclosure will Dot require HVAC, but will require overhead lighting and convenience electrical outlets for use by maintenance and operations personnel. Access to the enclosure will be via the existing chemical treatment building, the control building and/or two (2) double doorways to be installed on the west and east sides of the new enclosure.}

^{Treated EmueDt Chlorination System:}

^{The existing disinfections system injects chlorine gas into the treated effluent on the inlet side of the 3MGal clearwell. Excessive retention times, in conjunction with elevated TOC level, result in elevated levels of disinfection by-products within the clearwell and subsequently within the water distribution system. These elevated disinfection by-product levels fonn a significant basis for Consent Order Case No. 05-002A. Based on our engineering analysis, it was determined that the preferred alternative to mitigate this problem will be the construction of a supplemental chlorine gas disinfection system which will pennit the injection of chlorine gas directly into the treated effluentat the discharge side of the treated effluent pumping station. The addition of this chlorine disinfection system will permit significantly enhanced control of the chlorine residual within the treated effluent within the distribution system. In addition, it will permit better management of the chlorine residuals within the clearwell, allowing substantially enhanced control of the resident disinfection by-products.}

^{Filter Media Replacement / Rehabilitation:}

^{The Peny WTP contains six (6) filtration basins, each approximately 14.5-ft x IO.5-ft. Filter Nos. 1-4 were constructed with the original WTP in 1992 with Filter Nos. 5 & 6 constructed in 2002. Each of the filters contains the original filter media, containing layers of anthracite and sand. A study by Utility Service Company in 2008 indicated that the existing filter media in Filter Nos. 14 are severely coated with up to 40% calcium carbonate scale. Filter Nos. 5 & 6, indicate a moderate build-up of manganese, iron and calcium carbonate. The study results indicated that the change on treatment operations, instituted post-2002 have resulted in a decreased rate of calcium carbonate scaling, but the current condition of the media in Filter Nos. 1-4 indicate that these filters should receive replacement filter media. The media in Filter Nos. 5 & 6, should be treated to return these filters to optimal performance and to preclude permanent damage. Based on our engineering analysis, it was determined that the preferred alternative to mitigate this problem will be to remove and replace the filter media in Filter Nos. 1-4 and rehabilitate the filter media in Filter Nos. 5 & 6. As part of the filter media replacement / rehabilitation process, all appurtenant equipment within the filter basins should be inspected, repaired or replaced as determined to be appropriate upon field inspection by the Engineer.}

^{Automated Operator for 12-in Influent Valve:}

^{All raw water which is treated by the WTP enters the plant through the influent line located within the Chemical Building. There is an existing 12-in valve on this line which can be used to control the rate of flow which enters the WTP. Although the 12-inch valve exists, it requires manual operation which is problematic, given that the plant is typically lightly staffed and the valve location is far removed from the operations control room. Because of this situation, it has proven difficult to optimize plant operations, especially during periods when water demand or influent water chemistry vary rapidly. Based on our engineering analysis, it was determined that the preferred alternative to mitigate this problem will be to provide automation of the 12-inch influent valve, allowing operation of the valve remotely from the WTP control room and pennitting optimization of flow and plant operations.}

^{Sedimentation Basin Chain & Flight Sludge Collectors:}

^{Only one of the three (3) existing sedimentation basins is equipped with a motorized chain & flight sludge collector system. Due to this lack of equipment, the only method available for sludge removal in these basins is to take the unit out of service and manually remove any accumulated sludge. Based on our engineering analysis, it was determined that the preferred alternative to mitigate this problem will be to install motorized chain & flight sludge collector systems within the middle and eastern sedimentation basins.}