AWWA MTC64583

Many Southwest Florida utilities use the Floridan Aquifer System (FAS) as the source of rawwater for their drinking water production. Over the last decade several utilities have turnedto this source instead of shallow, freshwater aquifers, which suffered from reducing waterlevels and degraded source-water quality. In South Florida the FAS contains large quantitiesof brackish groundwater with good and uniform quality, is protected from human influencesby overlying confining layers and is therefore the preferred source in areas of limited freshgroundwater supply. The City of Cape Coral was one of the first cities to convert to the FAS. Due to rapid population growth, the City has begun a sizeable Utility Extension and FacilityExpansion Program to meet these needs. While keeping pace with this rapid growth, the City willalso increase the percentage of population served with drinking water via an acceleratedUtility Extension Program. Currently 71% of the population is served and this will increasefrom 85% in 2015 to close to 100% in 2020. Cape Coral is a pre-platted community thatrelies on domestic self-supply in areas not served by the Utility system. The potable demand is anticipated to increase from the current 14MGD to 29 MGD in 2015. The expansion of the existing Southwest ReverseOsmosis Water Treatment Plant (SWRO WTP) from 15 to 18 MGD is currently underway,to meet short-term needs. In addition, the construction of the new North Reverse OsmosisWater Treatment Plant (NRO WTP) with an ultimate capacity of 36 MGD, to meet the longtermdemands, has commenced. The first phase of the NRO WTP has been designed for acapacity of 12 MGD and will be operational in early 2009. The second phase providing anadditional 12 MGD of treatment capacity needs to be operational in 2015. Following the experience at the SWRO WTP and supported by groundwater modeling, theraw water quality is expected to deteriorate over time. The main contributor to this is that alarge percentage of the recharge to the production aquifer is through leakage fromunderlying, more saline aquifers. The raw water deterioration requires special designconsiderations for the NRO WTP. This paper presents a summary of the hydrogeology ofthe FAS, explains the background and concept of changing aquifer conditions over time andwill present the features included in the design of the NRO WTP to cope with thedeteriorating raw water quality. Many water utilities in Southwest Florida using brackishgroundwater are dealing with the same issue. Therefore this case study is a typicalrepresentation of the challenge of the Region's water supply. Includes 13 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

03/01/2007

Number of Pages:

16

File Size:

1 file , 2.3 MB