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

and after the Chlorine Injector Box in the effluent discharge pipe. I' i' I Up to approximately 1. 0 million gallons per day is distributed to the golf course through II irrigation spray heads sprinklers. The distribution of the effluent to the restricted access sprayfield is based on a time dataflow system. There are eight ( 8) zones within the restricted iii access sprayfield, which is rotated every 0.5 hours by a timer. The effluent distribution system for the restricted access sprayfield consists of a grid of spray heads on fixed risers. II Effluent from the WWTP is discharged into a 29.0 million gallon ( MG) lined effluent holding pond. The effluent is then pumped to the restricted access sprayfield from this pond using vertical turbine pumps located at the irrigation pump station or pumped through the sand filter for tertiary treatment and gravity fed to a 2. 0 MG aboveground holding tank located at the golf course public access irrigation system. The effluent from the 2. 0 MG storage tank at the golf pumped by a booster pump to the golf course. The booster pump at the golf course course site is I can be used to empty the 2. 0 MG holding tank effluent back to the holding pond during times of I F:\2001\ 01.0387. 000\Report\ R-4\ 041403 FINAL\SEC 2. doc HAI#01.0387. 000 2- 37 04/ 14/ 03 I Ii I maintenance operations. Manual control valves, located at the WWTP effluent discharge, are currently used to divert the effluent to the two ( 2) different disposal locations. I..'....,. II Presently, the sprayfields and the effluent disposal system are operating as designed. I I I I I I III II III III It. II' i Ii I. I F:\2001\ 01.0387. 000\Report\ R-4\041403 FINAL\ SEC 2. doc HAI#01.0387. 000 2- 38 04/ 14/ 03 I IIII SECTION 3 HISTORICAL AND PROJECTED WASTEWATER CHARACTERISTICS I 3. 1 HISTORICAL WASTEWATER CHARACTERISTICS I Wastewater is a combination of liquid and water- carried wastes from residences, commercial buildings, industrial facilities, and institutions, together with any groundwater and stonnwater I that may be present. As indicated previously, the existing wastewater users within the City consists of primarily residential with some commercial and light industrial. Since there has been I little growth over the last five ( 5) years, the wastewater makeup is relatively consistent. Another important characteristic of the wastewater is the rate at which the wastewater reaches the WWTP. I The fluctuations in flow nonnally experienced on an hourly, daily and monthly basis must be taken into account in evaluating any wastewater collection and treatment system. I The following subsections evaluate both the influent flow experienced at the City' s WWTP and the characteristics of the wastewater treated. Historical wastewater flow data from the City' s I WWTP were obtained from the infonnation provided by the City and the FDEP in the fonn of the electronic and hardcopy FDEP Discharge Monitoring Reports ( DMR's) for the period that I began on January 1998 through June 2002. The historical data for the WWTP analyzed includes influent and effluent wastewater characteristics, maximum, minimum and average daily I wastewater flows, and monthly average daily flows that was experienced at the City' s WWTP during this period. I 3 . 1. 1 Wastewater Flows I The FDEP DMR' s for the City' s WWTP were reviewed for the period beginning in January 1998, and ending June 2002. Summarized in Table 3- 1 and Figure 3- 1 are the historical I wastewater flow data for this period. The monthly average 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 I period. The maximum day flow during period was reported to be 8. 518 MGD, and occurred in September 1998 ( Hurricane Georges). I The higher influent wastewater flows experienced at the WWTP during this period appear to be attributed to III entering the wastewater system resulting from excessive rainfall events. This is I particularly true for the earlier portions of the reporting period and is shown in Figure 3- 2. I F:\2001\ 01.0387. 000\Report\ R-4\ 041403 FINAL\SEC 3. doc HAI#01.0387. 000 3- 1 04/ 14/ 03 IJ!. .~~ Ii  Infiltration is the groundwater, which leaks into the wastewater collection system generally through deteriorated and/or defective pipes, joints, connections, manholes and lift station wet I wells. Whereas, inflow is the stonnwater, which directly enters the wastewater collection system during or directly following a rainfall event from such sources as flooded manhole covers, direct I connections to the stonnwater system, and damaged cleanouts. Generally, the efforts by the City to control III have been most successful in decreasing inflow into the system. However, III issues are an ongoing concern of the City. They are continually assessing and developing a I program to repair the system to reduce the III into the system. Specifically, the City is addressing III coming from customer service laterals during high groundwater conditions I following substantial rainfall events. The hydraulic and sanitary effects of these extraneous flows are particularly important because urban growth creates the need for available wastewater I system capacity, and these extraneous flows limit the available capacity of the system. More importantly, the extraneous flows triggers unnecessary improvements and expansion of the I wastewater collection, transmission and treatment facilities. Based on the data reviewed, the maximum day to monthly average day ratio for influent I wastewater flow for period from January 1998 to June 2002 was detennined to range from 1.07 to 2. 80, and averaged approximately 1.23 as shown in Table 3- 1 and illustrated in Figure 3- 1. I As shown graphically in Figure 3- 2, the monthly average daily wastewater flows have shown a I general decreasing trend from January 1998 to June 2002. Documented in the Updated Capacity Analysis Report, dated September 1998, the City's plant flows have been decreasing for a number E 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 since 1992. There has been a constant commitment on the City' s part to minimize III impacts to the system. A secondary E reason is the City has enacted potable water conservation programs that have resulted in a decrease in water consumption, which in turn affects the quantity of wastewater entering the I system. E I i'.' i"" I F:\2001\ 01.0387. 000\Report\ R-4\ 041403 FINAL\SEC 3. doc HAI#01.0387.000 3- 2 04/14/ 03 I III II' TABLE 3- 1 CITY OF FORT WALTON BEACH EVALUATION AND ASSESSMENT REPORT iI WASTEWATER TREATMENT PLANT MONTHLY INFLUENT FLOW(!) I MonthlY ear Monthly Average Daily Flow (MOD) Three Month Average Daily Flow (MOD) Minimum Daily Flow (MOD). Maximum Daily Flow (MOD) . 5. 202 MDF/ADF Ratio 1.53 January 1998 3.407 data used in calc. 2. 273 3. 231 data used in calc. 2. 712 4. 065 1.26 February 1998 I March 1998 April 1998 3. 646 2. 432 3.428 3.1 03 2. 102 2.185 6. 771 2. 655 1.86 1.09 2.262 2. 780 2. 139 2.488 1.10 May 1998 2. 285 2.326 2. 033 2. 581 1.13 June 1998 I July 1998 August 1998 2.293 2.416 2. 280