In 2000 master planning studies conducted by the Hoopa Valley Public Utilities District's engineering consultant
Spencer Engineering & Construction Management, Inc. (Spencer) of McKinleyville,
California, determined that an additional water source of at least 0.5 million gallons
per day (mgd) was needed to serve present and future customers through the year
2021. The water sources at that time consisted of two pressure filtration treatment
plants located on mountain streams capable of producing approximately 0.58 mgd.
Traditionally, the Hoopa Tribal Council policy was to only utilize streams or creeks
for drinking water and not to use the Trinity River. However, due to unreliability of
these creeks and streams to sustain the required demands without endangering the
aquatic life during low flows and the difficulty in adequately treating these waters
during heavy rainfall events that result in high turbidities and clogging of intake
facilities, the Council agreed to utilize the water in the Trinity River. Due to the proposed plant size, location, and hydraulic conditions, two treatment
processes were studied and evaluated by the District's engineering consultant for this
project, Boyle Engineering Corporation (Boyle). These two processes were a
continuous microfiltration (CMF) process and a contact clarification/filtration
process. Each of these processes are considered as alternative filtration technologies
and are approved as such by the California Department of Health Services (DHS).
The advantages of these processes over the conventional treatment process in this size
range are their compact size, low costs, and easier expansion capabilities. Although
the District is not regulated by state or federal agencies, the District has adopted those
relevant standards of DHS and the U.S. Environmental Protection Agency (USEPA).
The USEPA, through the Surface Water Treatment Rule (SWTR), dictates the
maximum contaminant levels applicable to systems that use treated surface water.
The SWTR requires the water supplier to achieve a 3-log (99.9%) removal/
deactivation of Giardia cysts and a 4-log (99.99%) removal/deactivation of viruses. Includes tables, figure.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 900 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
| Published : | 11/01/2005 |
