Fort Walton Beach Council agenda — 04-29-03 workshop agenda — reading text

clarification. For the both treatment alternatives, $ 12, 500 has been I allocated for the removal and disposal of clarifier existing drive units. I I Sludge from the primary clarifiers is pumped to a gravity thickener, which in turn directs the sludge to the anaerobic digesters for further treatment. The pumping facilities consist I of two ( 2) sets of pumps for a total of four ( 4) pumps. The pumps are used r the f() removal of primary sludge and scum from the two ( 2) primary clarifiers. The pumping facilities were inspected and were detennined to be in good operating condition, and I therefore, no improvements are necessary. However, for the MLE process these pumps and the structure will be abandoned in place. The total capital expenditure including I F:\2001\ 01.0387.000\ Report\R-4\ 041403 FINAL\Excecutive Summary 041503. doc HAI# 01.0387. 000 ES- IO 04/ 14/ 03 fill i engineering, contingency, and pennitting to rehabilitate the primary clarifiers as related to the RBC process is estimated to be $ 325, 000. The total primary clarifier capital cost I allocation including engineering, contingency, and pennitting for the MLE process alternative is estimated to be $ 12, 500. II For the existing process, the wastewater stream discharges from the primary clarifiers by 1.<.' gravity to the RBC process units. The RBC system is made up of four (4) trains with five I 5) rotating units. Each unit is 25 feet long and 10 feet in diameter fitted with eight ( 8) sectors of four ( 4) quadrants of plastic media for the treatment of organic waste streams. I In each of the WWTP' s four ( 4) treatment trains there are three ( 3) standard density media units and two ( 2) high density media units. To improve process perfonnance and I reliability, replacement of the RBC units, drive systems, and weir gates is necessary. The RBC process rehabilitation includes an aeration system, dissolved oxygen monitoring, I and rehabilitation of the RBC structure. These improvements are recommended to improve process efficiency. The total capital expenditure including engineering, and pennitting allocated RBC rehabilitation is estimated to be I contingency, 2, 650,000. to I For the MLE process alternative the existing primary clarifiers and existing RBC basin would be utilized for flow equalization. The clarifiers and RBC basin would be equipped I with mixers, rails, supports and related components to stir the contents prior to entering the oxidation ditches. To utilize the RBC basin for flow equalization, a cost of $25, 000 i has been allocated for RBC unit removal and disposal. A total capital cost of $187, 500 is allocated to converting the existing basins to flow equalization. I The MLE process and sequencing to bring this process online would include the construction of a new secondary process facility, WAS/ RAS pumping facility, and associated yard piping. In addition, it is anticipated that the MLE anoxic/ oxidation ditch structure will require additional excavation to achieve the hydraulic profile necessary to 1;{":; eliminate the need for additional pumping. A capital cost of $312, 500 has been allocated for the additional excavation necessary for the oxidation ditch construction. The total I capital expenditure allocated to the construction of the oxidation ditch and associated equipment including engineering, contingency, and pennitting is estimated to be I 4, 262, 500. I F:\2001\ 01.0387. 000\ Report\R- 4\ 041403 FINAL\ Excecutive Summary 041503. doc HAI# 01.0387. 000 ES- ll 04/ 14/ 03 t II tj ill From the secondary clarifiers, the effluent flows by gravity to the chlorine contact chamber. The chlorine contact chamber consists of a single baffled chlorine contact basin. However, a primary concern with this basin is that it cannot be taken off-line to maintain and clean the tankage. At this time, the existing disinfection facilities are I adequate to meet the City' s wastewater disinfection requirements although the chlorine I contact chamber requires rehabilitation. An estimated cost of $ 125, 000 has been allocated to rehabilitate the existing chlorine contact chamber. This cost includes sealing the perimeter walls with epoxy and reconstructing the interior CMU walls; however, the improvements do not include costs for constructing an additional basin to accommodate I the ability to bypass the structure. I A sidestream of effluent from the City' s WWTP is used to irrigate the City public golf course. The WWTP effluent is passed through a denitrification filter prior to I transmission to the golf course to reduce nitrogen levels prior to application. The denitrification filter consists of four ( 4) Parkson Dynasand trains each with three ( 3) units. Additional filter capacity is necessary to treat the entire wastewater flow regardless of which alternative is chosen. The existing filters have a capacity of approximately 2. 1 MGD and approximately 2.4 MGD of additional capacity is required to treat the average P- II daily flow through the effluent filters, if operated in the denitrification mode, which would be required if the RBC option is used. However, for the MLE alternative nitrogen II is removed in the MLE process, the existing filters can treat approximately 3. 1 MGD. Therefore, approximately 1.4 MGD of additional capacity would be required. The cost to I construct additional denitrification filtration facilities to treat 4. 5 MGD is estimated to be I 812, 500 including engineering, contingency, and pennitting. Denitrification filtration is not required for the MLE process since this process achieves nitrogen removal to less m than 5 mg/l. However, the MLE process requires additional filters to accommodate the additional flows to treat 4. 5 MGD at an estimated cost of $ 187, 500, which includes L", engineering, contingency, and pennitting. II' ill The City' s WWTP is currently equipped with a 400 KW auxiliary diesel generation set with bulk fuel storage on- site. The generator has sufficient capacity to supply power to the existing RBC process in the event of a power outage although additional capacity will II be necessary with the projected WWTP improvements. The MLE process alternative requires approximately 300 KW of additional standby power due to the larger aerator I The motors and the addition of recycle pumps required for the activated sludge process. RBC process will also require additional auxiliary power due to the installation of the I F:\2001\ 01.0387. 000\Report\ R-4\ 041403 FINAL\Excecutive Summary 041503. doc HAI# 01.0387.000 ES- 12 04/ 14/ 03 iI it I diffused air system into the RBC basin. The estimated auxiliary power requirement for the RBC process is 150 KW. It is estimated that the additional standby generator will I cost $ 50, 000 for the RBC process and approximately $ 100, 000 for the MLE process, which includes engineering, contingency, and pennitting. I The total probable opinion of capital costs associated with the treatment process utilizing the RBC and MLE process alternatives are $ 4, 118, 750 and $ 4, 793, 750, respectively. I Details of these capital improvements for both alternatives are presented below in Table ES- 2. I I I I I I I I'.' iW 2 I I I I F:\2001\ 01.0387. 000\Report\ R-4\041403 FINAL\ Excecutive Summary 041S03. doc HAI# 01.0387. 000 ES- 13 04/ 14/ 03 I III II I TABLE ES- 2 Breakdown of Capital Improvements I Proposed Correction WWTP Problem Description RBC Retrofit MLE Oxidation Ditch Element I cost $) cost $) Roping in aerated grit chamber Smaller mesh in the screen Smaller mesh in the screen I 25, 000) 25, 000) High pressure flushing line I Clogging in grit feed line High pressure flushing line 18, 750) 18, 750) Screening and I Pretreatment Unequal & stagnant flows from Install weir gates ($ 25, 000) Install weir gates ($ 25, 000) pre- aeration basin 1----.--...--.-..........................-.-...............-. I Corrosion to concrete grit Rehabilitate with cleaning & Rehabilitate with cleaning & chamber & grit cyclone support resurfacing ($ 62, 500) resurfacing ($ 62, 500) structure I Primary Clarifiers Corroded bridge structures & Remove & replace drive units Remove drive units ($ 12, 500) I aged drive units 325, 000) Secondary 1!....,. 1, Treatment Unreliable