Ball K.,Louisville Water Company
North American Tunneling 2010 Proceedings, NAT 2010 | Year: 2010
During construction of Louisville Water Company's Riverbank Filtration Tunnel, a fault zone was encountered which yielded a continuous inflow of approximately 300 gallons per minute over 60 linear feet. Through the owner's desire for the lowest practical inflow criteria and restriction of potential undesirable groundwater chemistry from the bedrock, a consolidation grouting program was designed and implemented. The consolidation grouting program had minimal impact to construction and schedule. Consolidation grouting was performed after concrete forms had passed the zone but before they were removed. This negated the need to remobilize equipment and go through additional cleanup. Consolidation grouting resulted in greater than 99 percent reduction in groundwater inflow.
Ball K.,Louisville Water Company
Journal - American Water Works Association | Year: 2012
Louisville Water Company (LWC) has launched an innovative riverbank filtration (RBF) project at Riverbank Filtration Tunnel and Pump Station that uses the earth as a natural filter. The utility commissioned the US Geologic Survey (USGS) to study the aquifer that runs parallel to the Ohio River and to determine the quantity and quality of the groundwater supply. A full-scale test with a demonstration collector well that would pump 15 mgd from the aquifer began operating in 1999. The demo well met and exceeded all water quality and quantity expectations, pumping an average of 17 mgd. The project also provided 60 mgd of riverbank-filtered water to the B.E. Payne Plant. The decision on the type of well to drill was based on the ease of making the connection to the tunnel. The design allowed the wells to be capped at ground level, eliminating any aboveground structures from having to be located along the river-bank.
Louisville Water Company | Date: 2011-09-06
Rungvetvuthivitaya M.,University of Hawaii at Manoa |
Song R.,Louisville Water Company |
Campbell M.,Louisville Water Company |
Ray C.,University of Hawaii at Manoa
Journal of Water Supply: Research and Technology - AQUA | Year: 2014
Water utilities use operational strategies such as increasing pH, chlorine-ammonia ratio, and/or chloramine residual, distribution main flushing, and periodic break-point chlorination to control nitrification of chloraminated water in distribution systems. Although these methods are proven to be useful in controlling nitrification, the results are utility dependent and sometimes not effective in controlling the loss of chloramines. In various pilot studies, the direct application of chlorite at 0.1 to 0.8 mg/L is shown to be an effective alternative to control and prevent nitrification. Chlorite inactivates ammonia-oxidizing bacteria (AOB), the root cause of nitrification. In this study, we developed a kinetic model for nitrification inhibition through the addition of chlorite and the observation of residual chloramines and AOB. The important water quality variables examined were: chlorite concentration ranging from 0.02 to 0.4 mg/L, pH ranging from 7 to 9, ammonia concentrations ranging from 0.5 to 2.0 mg/L-N, and temperature ranging from 15 to 35 °C. Instead of measuring the viability of the AOB cells, the production of nitrite and the consumption of ammonia are used as surrogates for cell activity. This information was used to develop a kinetic model (modified Intrinsic Quenching model) that was able to fit the experimental data. © IWA Publishing 2014.
Williams A.F.,Louisville Water Company |
Coombs K.D.,Louisville Water Company
Pipelines 2013: Pipelines and Trenchless Construction and Renewals - A Global Perspective - Proceedings of the Pipelines 2013 Conference | Year: 2013
From 1992 until 2007, the Louisville Water Company (LWC) implemented an aggressive Main Replacement and Rehabilitation Program (MRRP) targeting approximately 500 miles of unlined cast iron pipe installed in LWC's system prior to 1931. With an annual budget between $8,000,000 and $10,000,000, cast iron pipes that were both structurally and hydraulically sound were cleaned and cement lined, and those that were not structurally sound or were hydraulically undersized were replaced. Following the completion of this targeted program in 2007, LWC has continued the MRRP with an annual budget of $5,000,000 targeting selected sections of lined cast iron pipe primarily for replacement. Selection criteria utilized included age, breaks, leaks, and main break frequency (MBF) as potential indicators of performance. LWC endeavored to find selection criteria that provided a more business-sense approach. The MBF has been a good standard measurement to compare breaks from one area or time period with another within LWC's system. It can also be utilized to compare against another water utility's performance, but it's not an indicator of how LWC is performing within an environment that speaks in dollars and cents. In selecting candidates, what level of MBF justifies the replacement of a pipe section? Because LWC is looking at a one-time capital cost for replacement in comparison to a series of recurring operations and maintenance costs for repairs, certain factors - including inflation, weighted cost of capital, service life, study life, and various other economic terms and calculations - need to be considered. In addition, the methodology employs "soft" data to "evaluate costs" of customer outages, traffic delays, criticality of pipe section, and likelihood of future failures. A Net Present Value (NPV) analysis is employed to examine a pipe section's candidacy for replacement. The paper discusses the background of LWC's original MRRP, previously utilized selection criteria, and details and illustrates how use of the NPV analysis has allowed the LWC's current MRRP to evolve and remain a prudent use of rate payer funds in an economically challenging business environment. © 2013 American Society of Civil Engineers.