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City of Paso Robles
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Address
Wastewater Division Treatment Plant
3200 Sulphur Springs Road
Paso Robles, CA 93446
Phone
(805) 237-3865
(805) 237-3886 FAX
Hours
Mon-Fri 7am to 3:30pm
E-mail
wastewater@prcity.com
Wastewater

TREATMENT PLANT

The Treatment Plant Process (continued):

Polishing Ponds  |  Laboratory

Previous Pages:
Physical Treatment  |  Primary Treatment  | Trickling Filters
Secondary Clarifiers  |  Bio Solids  |  Disinfection

Polishing Ponds

Image numbers are in parenthesis.

The stream is then discharged (24) into ponds (25) for final treatment. Chlorine dissipates out during the detention time in the ponds. A residual of chlorine is not allowed in the discharge stream (26 & 27) to the Salinas River during “live stream” condition.

24. 25.

26. 27.

Two types of conditions exist during the year in the Salinas River, “live stream” (28), meaning water is flowing on the surface or “no live stream” meaning water is not visible on the surface. The “live stream” condition exists approximately 20% of the year and the “no live stream” condition 80% of the year. These ponds are maintained and kept free of weed growth, and three of the ponds are dried out each summer and cleaned (29).

28. 29.

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Laboratory

Operators collect samples daily to perform laboratory tests; (30) they use the results to run calculations for the Plants process control. Sampling is also done on a monthly, quarterly, semi-annual and annual basis to monitor process control, and to report to the Regional Water Quality Control Board and the State Division of Water Quality (EPA).

Some testing is done in-house in the wastewater treatment plant laboratory. (32 below) The more complex testing is sent out to contract laboratories.

One of the more recent NPDES Permit laboratory requirements is for Toxicity. A composite sample (taken over a 24 hour period) is sent in for testing using three species: Fathead Minnows, Water Fleas, and Green Algae are used in a controlled environment to identify toxicants that may be found in the discharge stream. Ammonia continues to be an issue with the Toxicity testing which will be dealt with in the upcoming plant upgrade.

Previous Pages:
Physical Treatment  |  Primary Treatment  | Trickling Filters
Secondary Clarifiers  |  Bio Solids  |  Disinfection

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