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

Photos 2- 28 2- 16 Anaerobic Digesters Photos 2- 31 III 2- 17 Anaerobic Digester Photo 2- 32 2- 18 Residuals Dewatering Operations Photos 2- 33 2- 19 Plant Recycle Pump Station Photos 2- 35 3- 1 WWTP Monthly Flow vs. Maximum Daily 3- 5 3- 2 Rainfall vs. WWTP Flow 3- 6 fI! 3- 3 WWTP Flow Through Facility 3- 8 4- 1 Existing WWTP RBC - RBC Failure 4- 3 4- 2 WWTP Alternative No. 1 - Existing RBC Configuration 4- 7 I 4- 3 WWTP Alternative No. 1 - Existing RBC Drive System Configuration 4- 8 4- 4 WWTP Alternative No. 2 - Wes Tech ATM- Aerator Units 4- 14 I 4- 5 WWTP Alternative No. 2 - Wes Tech ATM-Aerator Configuration 4- 15 4- 6 WWTP Alternative No. 3 - MLE/ Oxidation Ditch Configuration 4- 18 I F:/ O 1/0 1. 0387 .OOO/ report/toc I11III HAI#01.0387. 000 Vll- 04/ 15/ 03 1H. J III II III CITY OF FORT WALTON BEACH WASTEWATER TREATMENT PLANT w FACILITIES PLAN LIST OF FIGURES ( Continued) I Section No. Page Title No. I!.."., II 7- 1 WWTP Facilities Plan 7- 3 B- 1 Effluent BOD5 B- 1 I B- 2 Effluent TSS for ROOl B- 2 B- 3 Effluent TSS for R002, Monthly Max B- 3 I B- 4 B- 5 Effluent pH, ROO 1 Effluent pH, R002 B- 4 B- 5 I I till III II" 1M ill II IIiII I I I: F:/ O 1/0 1. 0387 .OOO/ report/toc lilt HAI#01.0387. 000 V111- 04/ 15/ 03 II I EXECUTIVE SUMMARY m ES. 1 INTRODUCTION The purpose of this report is to provide the City of Fort Walton Beach ( City) with proper IJ: guidance necessary to plan and upgrade their existing wastewater treatment plant WWTP) to continually meet the effluent levels required by existing and future state and II federal regulations. This WWTP Facilities Plan not only provides the City with a plan of action for the WWTP' s secondary treatment upgrades, but also addresses other necessary I improvements outside of the secondary treatment process. These improvements include filtration, disinfection, residuals management, reuse alternatives, plant process pump I station rehabilitation, and pretreatment system upgrades. I ES. 2 EVALUATION OF WASTEWATER SERVICE AREA The City of Fort Walton Beach' s existing wastewater service area includes the south- I central portion of Okaloosa County encompassing approximately 7.4 square miles. The service area is bounded by Eglin Air Force Base to the north, Choctawhatchee Bay to the east, Santa Rosa Sound to the south, and Hurlburt Field to the far west. The area is dissected by the service area for Okaloosa County Water and Sewer. The service area I.. includes the City of Fort Walton Beach and Township of Cinco Bayou (population of about 540). Residential usage accounts for almost 50- percent of the land use in the City, while III commercial and industrial categories comprise approximately 16- percent of the total. I.. Public buildings, grounds and other public facilities represent 14- percent of the total land II1II use. Finally, recreational land uses account for approximately 12- percent of the area, and 1M undeveloped land represents approximately 8- percent of the City limits. The City of Fort Walton Beach' s wastewater system is comprised of a collection, transmission, treatment fill W and effluent disposal system, which, as of August 2002, provided wastewater service to a total of 8, 889 accounts. These accounts are designated as residential/ ight commercial, I industrial, or categorical industrial customers. The distribution is as follows: Residential/ Light Commercial: 8, 849. I Industrial ( no monitoring required): 39 Categorical Industrial ( required monitoring): 1 II F:\2001\ 01.0387. 000\Report\ R-4\041403 FINAL\Excecutive Summary 041503. doc HAI# 01.0387. 000 ES- l 04/ 14/ 03 II filii II The total number of wastewater customers receiving service from the City has remained very constant over the past 5 years; with as few as 50 additional customers since 1998, based on a review of the City' s billing records. This is also supported by the low percentage ( 8%) of undeveloped land in the City. Generally, the service area can be considered as " built out". Ii ES.3 EXISTING FACILITIES III The City WWTP was constructed from 1979 to 1980 and was upgraded in 1992, with the I addition of tertiary filtration to a public access sprayfield, high- level disinfection for portions of flow going to the public access reuse sprayfield ( R002), and modifications to iW the existing sprayfield to reduce ponding during periods of wet weather. The plant is located off Lewis Turner Boulevard on Percy L.Coleman Road. The existing facility is II presently pennitted to treat 4.50 million gallons per day ( MGD) maximum month average daily flow with up to 1. 55 MGD tertiary filtration to the public access reuse ( golf course). Wastewater flow to the WWTP is conveyed by the City' s wastewater collection ill and transmission system which consists of approximately 106- miles of gravity sewer, 13- III miles of force mains and 42 wastewater lift stations, strategically located throughout the ill current wastewater service area. II. The City's WWTP is a fixed film rotating biological contact facility that discharges effluent to one (1) restricted access sprayfield and/ or the City' s municipal golf course. III Other components of the treatment process include pretreatment ( screening, pre- aeration and grit removal), primary and secondary clarification, and disinfection. The sludge generated within the wastewater treatment process is treated and dewatered. The dewatered stabilized sludge is hauled off-site by the City and disposed of at an agricultural use site near Freeport, Florida. The City of Fort Walton Beach WWTP currently operates under FDEP Pennit No. Ii",j FLAI01923- 002- DWIR1NR, which expires on April 1, 2004. I ES.4 HISTORICAL AND PROJECTED WASTEWATER CHARACTERISTICS previously, the existing wastewater users within the City consist of I As indicated primarily residential with some commercial and light industrial. Since there has been little growth over the last five ( 5) years, the wastewater makeup is relatively consistent. I F:\2001 \ Ol. 0387.000\ \ - 4\ 041403 ReportR FINAL\Excecutive Summary 041503. doc HAI# 01.0387. 000 ES- 2 04/14/ 03 filii i.a III 1.,, 1 I Another important characteristic of the wastewater is the rate at which the wastewater reaches the WWTP. The fluctuations in flow nonnally experienced on an hourly, daily I and monthly basis must be taken into account in evaluating any wastewater collection and treatment system. I The FDEP Discharge Monitoring Reports ( DMR' s) for the City' s WWTP were reviewed for the period beginning in January 1998, and ending June 2002. The monthly average I daily wastewater flows for this period ranged from 2. 035 MGD to 4. 249 MGD, and averaged 2. 563 MGD during this 4- year, 6- month period. The maximum day flow during I period was reported to be 8. 518 MGD, and occurred in September 1998 ( Hurricane Georges). The higher influent wastewater flows experienced at the WWTP during earlier portions of the reporting period appear to be attributed to inflow and infiltration ( III) entering the I. wastewater system resulting from excessive rainfall events. Inflow is water discharged fill' into service connections and wastewater pipes from foundation and roof drains, outdoor paved areas, cooling water from air conditioners, and other direct discharges from other sources. Infiltration is groundwater entering wastewater pipes and building connections III through defective joints and cracks in pipes and manholes. Generally, the City' s efforts in recent years to control III have been successful in decreasing inflow into the system. However, III issues are an ongoing concern of the City. Specifically, the City is addressing III coming from customer service laterals during high groundwater conditions following substantial rainfall events. The monthly average daily wastewater flows have shown a general decreasing trend from January 1998 to June 2002. Documented in the City' s Updated Capacity Analysis Report, dated September 1998, the City' s plant flows have been decreasing for a number II of reasons. The primary reason is an aggressive III program has removed significant amounts of outside water from the system. This program has been ongoing