Industry pros to lead irrigation workshops

- Fall 1999 "Update" Newsletter Article -

Sand in your water?

CIT engineer offers methods for controlling sand
in urban, ag water supplies

Sand in the water supply can be a constant and annoying problem for urban water users. In even minor concentrations in residential systems, sand can plug shower heads, distort the pattern of faucet aerators and cause leakage in toilet flush valves.

These difficulties, however, can pale in comparison to the serious effects of sand in an agricultural irrigation system, notes irrigation engineer Ed Norum in a new Center for Irrigation Technology (CIT) publication addressing the problem of sand in water supplies. While sand in a residential system can cost a homeowner hundreds of dollars in repairs, sand in a large agricultural system can be devastating to an enterprise if it restricts water flow to acres of crops.

In the new Irrigation Notes publication, titled "Gritty Problems Call for Irrigation Technology," Norum discusses how sand can enter a water system and what an irrigation manager can do to mitigate the effects.

Through 18 years of research evaluating and testing various screen, disc, sand media and sand separator products, CIT has compiled extensive data on the behavior of sand in a system and the effectiveness of certain types of filters, Norum said.

To filter sand from a system, Norum suggests three common filters types that can be used either individually or in combination with each other. They are screen filters, disk filters and hydrocyclone separators. Depending on the amount of sand and size of grains in the system, different filters might be used.

"If the design requires removal of all particles larger than a specific size, a disk filter is more likely to meet this objective," Norum writes. "If, however, significant amounts of sand are present, the sand separator is preferred because of its ability to store trapped sand and purge it free of the system with a minimum of waster water." Disk and screen filters require major backflows to insure complete purging, he said.

In the final analysis, the "best possible commercial answer" is to use a sand separator capable of removing at least 95 percent of total particulates, followed by an in-line sand or disk filter capable of removing at least 95 percent of the remaining contaminants, Norum concludes.

"This standard can be met by commercially available hardware," he said.

The publication is available for viewing or printing from the CIT web site at cati.csufresno.edu/cit It can be requested in hard copy format using the order form on Page 7.

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