The purpose of this study was to evaluate the condition of the existing Alfred Merritt Smith Water Treatment Facility (AMSWTF) filters. AMSWTF is a 600
million gallon per day (mgd) (2,270 Megaliters per day) direct filtration treatment plant, utilizing
ozone oxidation as the primary disinfectant and free chlorine for secondary distribution system
disinfection. Due to the declining level and deteriorating water quality in Lake Mead, the plant's
sole raw water source, the AMSWTF has recently experienced shortened filter runs. Although
the recent lowering of the plant intake has improved the raw water quality, reducing the influent
turbidity, particle counts and temperature back into historical ranges, lake levels are predicted to
continue dropping. Evaluation of the filters is the first step in preparing the plant for future
declines in water quality.
The evaluation process included a review of the filter and backwash operations, as well as an
assessment of the filter media characteristics. Four filters each from Phases I and II and two
filters from Phase III were chosen for evaluation. Individual filters were selected with input from
the plant operators and staff based on their observation of shorter filter runs, higher effluent
turbidity, early particle break through and suspected media and support media upset. The major
unit processes at AMSWTF, and the three filter complexes that make up the filtration process are
shown in relation to the rest of the facility, while the individual filters chosen for
evaluation are presented in a simplified plant schematic. Filter data from all three
phases of construction were reviewed including an assessment of the filter and backwash
operations. In addition, an assessment of the filter media characteristics was performed which
included filter bed core sampling, sieve analysis, floc retention profile analysis, spent filter wash
water turbidity profiling, filter excavation and gravel bed profiling. Data taken from Filter
No. 15 constructed during Phase II in 1982 was chosen for this study. Includes figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 760 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
| Published : | 06/17/2005 |
