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Well Case Study #1

Water Well Rehabilitation

Well Dom 219-02 September 2020

California Water Service (Cal Water) is the largest regulated American water utility west of the Mississippi River and the third largest in the country. Formed in 1926, the San Jose-based company serves 489,600 customer connections through 28 Customer and Operations Centers throughout the state.

Cal Water is the largest subsidiary of the California Water Service Group, which also includes Washington Water Service, New Mexico Water Service, Hawaii Water Service, HWS Utility Services, and CWS Utility Services.


As a whole, the Group provides high-quality regulated and non-regulated utility services to approximately 2 million people in 100 communities. Company-wide, our employees share a commitment to being the leading provider of water and wastewater services and delivering quality, service, and value to our customers.

After the initial brushing with a mud remover product and bailing, HCT/Well-Klean was asked to review and make recommendations.

Well Dynamics:

Potable Water Extraction Well
Off-line 4 years.
19 years of age.
Casing is louvered copper bearing steel. Casing is 16 inches diameter.

Standing water level 42 ft. Total Depth 710 ft.
Fill in casing 9 ft.
LSI Value – slightly scaling (0.6)


Unique Properties: Lined

Rehabilitation Techniques Deployed:


(2) 53 Gallon drums- Water Solv BC
(3) 305 Gallon Totes Water Solv BC
(4) 265 Gallon Totes Well Klean Pre-Blend (10) 50# bags of Sodium Bicarbonate


HCT Notes:

  1. We choose to clean the entire well as it "appears" to contain calcium phosphate from SWL to total depth. CaPO4 will support bacteria as well as premature bacteria colonization of the well.

  2. Based on the ground water LSI, this water is moderately scaling, though LSI does not incorporate the PO4 in its equation. The ground water is actually very scaling with the PO4 presence. The silica is high but not a concern as the CaPO4 has likely kept it sequestered, free form forming silicate scale (glass in a sense). Sulfate, Iron and Manganese played a minor role, as we would assume the bacteria had preference on the phosphate.

  3. The CITM scan exhibited concerns at blank casing intervals of 390 to 405, and also 500 to 505. These should be collectively reviewed, discussed and decisions documented to mitigate any casing damage.

  4. If this well sits stagnant for more than a few days, it should be saturated with layup chemistry containing sodium bicarbonate and HCT's WaterSOLVTM BC. Adequate flushing to waste would be required by NSF 60 Standards.

  5. This well will require bio and CaPO4 remediation perhaps once every 1-2 years. This can be accomplished insitu, pump in place by assuring the well check valve can be manipulated open so that surging the well can be performed (rawhiding).

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