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WSP06476
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Last modified
1/26/2010 2:22:57 PM
Creation date
10/12/2006 1:39:26 AM
Metadata
Fields
Template:
Water Supply Protection
File Number
8271.300
Description
Colorado River Basin Salinity Control Program - General Information and Publications-Reports
Basin
Colorado Mainstem
Water Division
5
Date
6/1/1978
Title
Salinity Management Options for the Colorado River -- Part 1 of 2 -- Title Page - Page 168
Water Supply Pro - Doc Type
Report/Study
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<br />Data CoUoetlon <br /> <br />'~:;l <br />:~) <br />N <br />-J <br />r-~ <br />o <br /> <br />A survey questionnaire was dsveloped and <br />applied to plumbers and appliance servicemen in areas <br />for which there were differing concentrations of <br />salinity in water supplies in an attempt to obtain <br />useful estimates of typical lifetimes of those goods <br />suspected to be affected by salinity. Questions were <br />aimed primarily at obtaining estimated typical <br />lifetimes for various capital.cost items that had been <br />identified in previous studies as being affected by <br />salinity concentrations. In addition, the question. <br />naires attempted to obtain estimates of repair or <br />replacement costs. <br /> <br />For the estimates of this study to be comparable <br />to other work in this area, TDS was used as an <br />appropriate measure of salinity. In order to generate <br />data that could be applied to regression studies, it was <br />necessary to find various locations for which the TDS <br />concentration differed. The primary criteria for <br />acceptance of various Los Angeles neighborhoods as <br />possible survey locations were based upon the length <br />of time that the area in question had received a single <br />source of water, the extent to which the area had <br />received a single source, the nature of differing water <br />sources, and the availability of water records. With <br />these qualifications in mind, three major locations <br />were selected: San Fernando Valley, Costa Mesa. <br />Newport Beach, and Long Beach. Each location had a <br />constant water supply source for at least twenty years <br />and a long time series of water quality data were <br />available. Each area had a different TDS level: San <br />Fernando Valley, 210 mg/l; Costa Mesa.Newport <br />Beach, 728 mg/l; Long Beach, 759 mg/l and 457 mg/I <br />from two different locations. <br /> <br />A list of potential respondents was developed <br />from current telephone books and calls were made to <br />set appointments for a field researcher to go through <br />the survey with the respondent. This was necessary to <br />restrict the response"to a single socio~economie unit. A <br />major problem with this survey procedure was the <br />difficulty in arranging appointments and persuading <br />the respondent to give up the time necessary to <br />complete the survey form. In view of this problem, a <br />second approach was used wherein survey question. <br />naires, with complete instructions, were mailed to the <br />respondent. As a result of the two procedures, a total <br />of 87 responses were received. <br /> <br />Statistical Tests <br /> <br />Since the sample size in each of the areas was <br />approximately 30, it was appropriate to use a <br />t.Statistic. The calculations for statistical significance <br />are recorded in Table 20. These tests did not take into <br />account alternative distributions or socio-economic <br />variables. However, the results did conform with <br />previous data in that there is no substantial TDS <br />related corrosion in pipes with the exception of <br />galvanized pipes. The major impacts of higher salinity <br />levels are upon household appliances, faucets, and <br />water heaters. <br /> <br />The next statistical test involved the use of <br />multiple regression analyses designed to examine the <br />relationship between water salinity and the estimated <br />lifetimes of various appliances or water conveyance <br />systems and the effect of certain socio.economic <br />variables upon this relationship (Table 21). In general, <br />TDS tended to be the most significant predictor of <br />lifetimes, but appeared to have little influence on <br />copper piping, toilet flushing mechanisms, and cast <br />iron wastewater pipes. <br /> <br />None of the socio.economic variables was consis. <br />tently significant although "number of persons per <br />unit" and "percent renter occupied" were often <br />important. Conceivably, these variables reflect the <br />level of use that an item receives. In general, there <br />was evidence that the physical damage due to salinity <br />is significant and that this damage may not be strictly <br />linear over the 200.700 mg!l range of TDS. <br /> <br />Economic Damage COlllPutatlons <br /> <br />Damage cost functions were developed by <br />estimating costs for each. water affected appliance or <br />pipe identified earlier. Cost estimates were assumed <br />to have a time horizon equal to the economic lifetime of <br />a typical housing unit. As such, the present value of <br />any given cost would be related to TDS through the <br />relationship between the lifetime of an article and the <br />TPS concentration. <br /> <br />S\IDIlD8I'Y <br /> <br />A comparison of the distribution between Costa <br />Mesa (728 mg/l TDS) and San Fernando Valley (210 <br />mg/l) indicated a statistically significant difference in <br />estimated mean lifetimes. The Costa Mesa.Newport <br />Beach area had a shorter estimated mean lifetime for <br />dishwashers, washing machines, garbage disposals, <br />brass faucets, water heaters, and galvanized pipes at <br />the 10 percent level of significance. No significant <br />difference was found for the other water conveyance <br />systems or fixtures at that same level of significance. <br /> <br />The regression analysis, which examined the <br />relationship between estimated lifetime, total dis. <br />solved solids, and the socio-eeonomic variables, found <br />none of the socio-economic variables to be significant <br />other than the number of persons per household. This <br />result may have been due to a lack of substantial <br />variation in household characteristics across the two <br />loCations or an incorrect specification of the relevant <br />economic variables. Further research is needed before <br />it could be concluded that differences in socio. <br />economic characteristics have no impact on physical <br />deterioration of household water systems. <br /> <br />Estimated economic losses for a typical Los <br />Angeles household, with the discount rate having <br />been set at 8 percent, ranged from $620 to $1,010 in <br />present value terms for an increase in TDS from 200 <br />mg/l to 700 mg/l. The estimated economic losses are <br />two to three times higher than those previously <br />reported in water resource literature. Aggregate <br />damages to households in the Los Angeles metropoli. <br /> <br />20 <br />
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