City of spearfish completes water audit local news electricity vocabulary

The document explains that department staff performed a water loss audit, checking numbers and the programs used to determine the numbers, Excel and Incode. Baker explained that the first step was to manually total each well’s monthly water production, and staff found a couple of months where the well meters rolled over.

The staff next defined which accounts were being used when totaling the metered accounts in Incode, and after looking at the usage, staff discovered that irrigation was being added in twice. “This error made it appear that usage exceeded production during months of high irrigation,” Baker writes. “Initially these meters were read manually, but transition to remote reading had left discrepancies between totals in Incode and totals on Excel. Reconciling these differences resulted in correction of the values audited between programs.”

Another issue discovered during the audit was that non-potable and Spearfish Valley Sanitary District water were being added to the total metered uses. “However, these usages are not from City water production and should therefore not be added to total usage. After entering the correct values into Excel, the percent accounted for each more began to follow a more likely trend. When we first started the percentages had approximately 40% difference between months,” Baker writes. “After fixing the issues stated earlier we noticed the difference was now closer to 20%. Additionally, while the percentages indicate a higher loss in the winter months, we determined that the total gallons reflected higher loss in the summer.”

Robert Glenn, water/wastewater utilities superintendent, addressed the Spearfish City Council Monday, providing a more in-depth presentation about the water audit. He described apparent and real losses. Apparent losses are unauthorized consumption, or theft, and customer metering and data inaccuracies, with real losses including leakage on mains and service lines, and leakage and overflows at storage. All of the losses lead to non-revenue water, clean, treated water that is lost before it reaches the customer, and the American Water Works Association (AWWA) describes the national average of non-revenue water loss to be between 10-30 percent.

Sources of non-revenue water includes leakage, billing meter inaccuracies, firefighting, water main breaks, water quality, and unauthorized use. Glenn showed examples of leaks, as well as measurements of leaks. For example, a hole that is one-sixteenth of an inch can leak 690 gallons in 24 hours, or 20,700 gallons in a month. A quarter-inch hole can leak 11,030 gallons in 24 hours, or 330,900 gallons in one month.

“That’s like from here to Wall,” he said, adding that there are more than 4,000 customer connections within that system, adding another 35 miles or so of customer pipe. “So if you take a quarter-inch hole, which is the size of the end of this pen, if you had 44 of those on that 100 miles of pipe, that would account for that total amount of water loss that we had last year.”

There are different kinds of leaks: unavoidable/background leaks, which make up 28.6 percent of national average; detectable/unreported leaks, which make up 65.5 percent — but of which only 4.4 percent are identified with existing leak detection programs; and observable leaks/reported failures, at 5.9 percent.

Glenn explained that in 2017, the price per thousand gallons was approximately .002 cents to produce. The total pumped was 715,836,045 gallons, and of that, 175,695,878 gallons were non-revenue water, which at the rounded price, cost the city $331,270.45.

The infrastructure leakage index is 3.19, and Glenn explained that this measurement is the ratio of water that is actually leaking, compared to water lost as a theoretical minimum called unavoidable loss, a calculation involving the miles of services lines and mains, connections, and pressure. The range is 1.0 to 8.0, with lower numbers being better.

Glenn added that specific areas of concern to be addressed include the city campground area; Winterville Loop; Ramsdell subdivision service line; booster station zones/Colorado Boulevard transmission line; and Roughlock Lane service lines. Outlying area water hydrants have also been locked and more closely monitored for theft, with a new hydrant meter program instituted so the city can check the readings.

“The fire department does have the ability to get into those very easily,” he said, adding that after the hydrants were locked, the city received calls of complaint from people wondering why they could no longer get water from the hydrants. “People were upset when they found out that they had to go buy it.”

Where the department goes next, Glenn said, is to continue the city’s active leak detection program, repairing leaks as they are found and require service lines be repaired; pressure testing of water mains; replacing large meters (10,000 gallon reads), which has already started, at an estimated cost of $53,000 for about 50 meters; replacing old/faulty meters as they are found; continuing to address database inconsistencies in Incode; and improving supply meter accuracies by replacing three existing well meters and calibrating all well meters.