The City of Morro Bay is located on the central coast of California about midway between Los Angeles
and San Francisco. In the late 1980s and early 1990s, California suffered a drought. The City
constructed a 0.58 MGD desalting plant. The water supply for the desalting plant comes from wells
located on the beach fronting the Pacific Ocean. The plant began operation in early 1993. The desalter
operated for several months and was then shutdown following the "miracle March" rains.
In 1995, there was again a shortage of rainfall and the desalter was returned to service. However, high
precipitated iron concentrations in the well water supplied to the desalter required changing the cartridge
filter elements at intervals of about 1/2 hour. It was impractical to operate the desalter because of the
cost of changing the filter elements and also because there was insufficient cartridge filter capacity to
maintain feedwater flow to the RO equipment because the filter elements were having to be changed too
frequently.
The City received notice that the supply of imported water from the California State Water Project was
to be interrupted for at least one month beginning about November 1, 2002, so that maintenance of State
facilities can be accomplished. Less than normal rainfall and contamination of some of the City's well
water limited the City's other water supplies. It was determined, therefore, to use the desalter to meet the
City's water needs.
However, it was first necessary to reduce the iron problem. Boyle Engineering was retained to
recommend a method to solve the iron problem. Two solutions were pilot tested for a short period of
time that included:
addition of chemicals (acid and a reducing agent) in an attempt to redissolve the iron that
accumulates in the cartridge filters; and,
filtration to remove the iron ahead of the RO system.
The pilot tests indicated that installing an iron filter to treat the incoming well water would be the most
economical, reliable means of solving the iron problem. Accordingly, in late summer of 2002, the City
determined to install such a filter. Due to the approaching shutdown of the State water supply, the City
adopted a "fast-track" approach to designing and installing the filter. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 390 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 03/05/2003 |
