04/07/2008 Council Packet - Laserfiche WebLink

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Managing how often people can water their lawns is the simplest and most effective way to control peak demand. To illustrate the importance of keeping the odd /even ban to control peak demand, suppose 45% of residents water on Day 1 and 55% residents water on Day 2 (Lifting the odd /even ban will certainly create more day -to -day variability). This creates a total water sprinkling demand of 2,222,000 gallons (see table below) on Day 2. If 70% of residents choose to water on a particular day, demand for watering lawns is 2,829,000 gallons, further increasing the demand of water storage /production (This may be a result of a hot day where people want to make sure their lawn is sufficiently watered or pure randomness). Total Residential Summer Consumption (4,041 households) 228,497,000 gallons Consumption for Watering per Day: 55% residents (2,222) x 1,000 gallons = 2,222,000 gallons 70% residents (2,829) x 1,000 gallons = 2,829,000 gallons Placing additional stress on the water system creates the potential of our system being susceptible to trouble (i.e. low water pressure, inadequate water reserves for fire, tower levels at zero, etc). We are experiencing a major shift from the peak demand times during the winter (6:00 - 11:OOam) to earlier peak demand times during the summer (3:00- 8:OOam). The attached chart shows the tremendous consumption increases in the early morning hours during the summer. This is a direct result of watering lawns. We are addressing the unacceptable high levels of watering lawns by using the tools we have. In addition to controlling peak demand, the odd /even ban also helps reduce consumption by not allowing residents to water every day. If we can reduce the top 15% of residential users to "only" consume 100,000 gallons during their summer quarter, we will conserve 23,000,000 gallons of water. Not only will lifting the odd /even ban have a negative effect on our system (unless we want to build additional well houses, storage tanks and pipes), we will no longer be following our Water Conservation Plan submitted to the DNR. We need to continue our efforts in conservation to better our chances of the DNR approving any future applications for well permits. The odd /even ban is the most effective /simplest tool available that assists us controlling peak demand. Rather than allowing up to 100% of residents to water any /every day, the odd /even ban reduces the potential users on any particular day to 50% of residences. Staff recommends that the odd /even ban remain because it's necessary to ensure we have adequate tower levels. If the odd /even ban is lifted it won't be a matter of "if" our water system will reach critical levels but "when." C:\Documents and Settings \rick.degardner.METRO -INET \Desktop \Odd Even scenario to counci #21.doc 4/4/2008 • • •