Well_22_Condition_Assessment_(6.10.25).docx

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Memorandum

Date: June 10, 2025

From: Gwyn-Mohr Tully Kris Olof

965 University Avenue, Suite 222 Sacramento, California 95825

(916) 669-9357

701 University Avenue, Suite 205 Sacramento, California 95825

(916) 669-9357

Subject: Well 22 Condition Report

The purpose of this assessment is to consolidate all of the various reports related to well 22 and give a summary of the condition of the well, including descriptions of pictures taken down the well casin. The results of this assessment will be used to determine if the well is to be repaired or to be replaced.

Background The City of West Sacramento Well 22, also know as state well number 9N/4E-33D1 was drilled in June of 1974 to a depth of 751 total feet but only lined to 692 feet. The initial well was tested at 1,500 gpm and appears to have been operating at that approximate flow rate at the time it was taken offline. The bore log shows alternating layers of clay and sand down to 690 feet. Below 690 ft is a clay layer. The well was initially built to 16” diameter but was subsequently modified to something less. The well casing appears to be 0.25” wall mild steel. The well is unique as the screen portions of the casing are all simply 10 foot sections of screen spread through out the column to align with some of the sandy layers. All of other listed well features are consistent with other City Wells of the period. This well was drilled by Washing Water and Power Company that would become the East Yolo Community Services District and eventually the City of West Sacramento Public Works Department. As is common as companies change hands, records of the well are sparse.

Inspection Findings An initial inspection was conduced on January 22, 2022 by Bennett Engineering Services. Their report found the site to be in largely good condition, likely repairable, and requested a down camera video-feed to assess actual well conditions. The following is a quote from the Bennett Engineering report:

“Well 22 is located between Oak Street and Harbor Blvd in West Sacramento. Well has been capped and the pump and equipment removed. The site still has a steel tank that is used for storage and is integrated into the water distribution system. A new power drop, well pump, valving, and piping would be required to re-integrate this well into the distribution system. Treatment of the water would need to be determined based on water quality samples taken after a well rehabilitation effort. But chlorine injection is anticipated at a minimum for residual disinfection. There is adequate room on the City owned property to build the systems necessary to re-establish Well 22. The condition of the well casing is unknown and will need to be swabbed, purged/pumped to waste, and video inspection completed to assess its viability to operate at a production level for supplemental supply. “ Eaton Pump was later tasked with assessing the well by completing a well health check which was to comprise swabbing, pumping, and video inspecting.

Video Inspection It appears that a video inspection was completed by Eaton Pump prior to any swabbing and no swabbing was actually completed before Eaton Pump ownership change. The previous ownership, which completed the video inspection, left the company and the video log and test results were left incomplete on Eaton’s systems. Zanjero was able to work with new ownership at Eaton to locate the video log and the information below represents the findings for discussion.

Video Summary: The down video well log consists of a camera and light dropped vertically down the well to the bottom before rotating the camera horizontal and spinning the camera in circles as it is pulled back up. The result in a vertical view down and then a casing view back up. The length of the cable extended from the camera rig is superimposed over the video so the depth at any time is visible.

Video Down:

Well Depth 0 to 10ft – Rusty casing with limited scale and evidence of issues.

Well Depth 16ft to 29ft - Heavy rust and flaking on interior of casing, oily sheen on water surface

Well Depth 29ft to 381ft – Cloudy surface water with limited visibility.

Well Depth 382ft to to 550ft – First screen section, heavy fouling

Well Depth 682 – Heavy Sand, falling from higher in casing.

Video up:

Well Depth 665 to 675 – Lowest Screen, filled with material, needs to be scrubbed Well Depth 659 to 665 – Smooth Casing, no issue Well Depth 649 to 659 – Moderate material buildup in screen 4 of 5 Well Depth 493 to 649 – Smooth casing, evidence of scratches/previous scrubbing Well Depth 483 to 493 – Moderate screen buildup screen 3 of 5 Well depth 424 to 483 – Small pock marks on casing, evidence of sediment sticking Well Depth 414 to 424 – Heavy Screen Buildup screen 2 of 5 Well Depth 396 to 414 – Smooth Casing Well Depth 385 to 395 – Heavy Screen buildup screen 1 of 5 Well Depth 350 to 385 – Minor pock marks on casing Well depth 270 to 350 – white scale flakes, evidence of green organic matter Well depth 267 to 270 – Pocked casing Well depth 266 – Horizontal split in casing

Well Depth 244 to 266 – Mild corrosion, smooth casing Well depth 243 – Heavy flaking and corrosion, starts at seam but extended vertically

Well depth 200 to 242 – Moderate streaking Well depth 188 to 200 – Heavy streaking and corrosion, evidence of sand infiltration and organic growth.

Well depth 172 to 188 – Moderate corrosion casing Well Depth 171 – Evidence of split casing with corrosion and sand infiltration.

Well depth 150 to 170 – Streaking and minor flaking of casing Well depth 136 to 150 – Heavy flaking of casing, evidence of layer missing Well depth 135 – Evidence of leaking seam Well depth 60 to 134 – Heavy flaking

Well Depth 50 to 60 – moderate flaking, heavy organic growth Well depth 30-50 - Heavy organic growth

Well depth 30 to surface – Rusty and flakey Professional Opinions After completing the inspection findings above, they were shared with a few experts in the field for their professional opinions and suggestions.

Eric V – Retired Well Tech “The split and sand at 193 is the likely source of the sand on the bottom of the casing. It is likely that swabbing will knock loose the material at 171, 193, and 272 with the result being same filling the casing above the screened sections. You could line the well above the screens but you would need a 12” liner which would mean 8” pipe and pump which would limit you to ~500gpm.”

Ryan J – Municipal Well Installer “That looks like a great way to lose a swabbing tool.”

Zanjero Recomendation After seeing the condition of the casing and understanding the low likelihood of lining being successful we recommend a full replacement. Even if the odds were better for a successful lining, the resulting flow rate would be insufficient for the effort involved and not be a meaningful supply when compared to a new well. Additionally, new wells are required to be stainless steel which will allow for more regular swabbing and cleaning and prevent the scale and organic buildup seen in the current well.

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