Report on City Water Plant (by former plant operator, Joe Robbins)
September 8, 2016
Junction Water System Overview
Junction's pre-treatment and membrane water plant can make 2 million gallons of drinking water daily from raw water pulled from the South Llano River by two 1,400 gpm submersible pumps (one operates at a time) that send the water to the pre-treatment plant where chlorine is added (beginning of Disinfection Zone I). In the pre-treatment plant, the water flow is divided between two Neptune micro floc sand filters with a capacity of 700 gpm each. This is where the bulk of turbidity removal takes place.
A 700 gpm pump (and a spare) behind each sand filter pushes the water into the head tank that turns the raw water pump on and off. The three Variable Frequency Drive (V.F.D.) pumps (one spare) pull water from the head tank through two sand screens (one spare) and push it through to the membranes. The V.F.D. flow is controlled by computer through feedback from each membrane unit (91 membrane units per skid). Water passes out of the skids and by a chlorine detector (end of Zone DI) and on its way to the Clearwell tank chlorine is injected (beginning of Zone D2). The Clearwell tank holds 300,000 gallons.
When the water leaves the Clearwell on its way to the high service pumps, it passes another chlorine detector (end of Zone D2). The high service pumps (3 total/1 spare) push the water out into distribution and fill the Round Top and Little Mexico water storage tanks. On/off for the high service pumps is controlled by water levels in the tanks and sent by radio frequency to the computers in the water treatment plant. The Bluebonnet tank is controlled the same way and the pumps (2 total/l spare) pull the water from the Round Top tank. The area served by the Round Top and Little Mexico tanks is one pressure plane (64 lbs static) and the area served by the Bluebonnet tank is another pressure plane (100 psi).
Initial Assessment of Pre-Treatment
1. The computer touch screen by which each unit is operated is missing, out of commission, and is out for repair.
The units still backwash automatically on a timed basis, but cannot be back washed manually, which is needed in times of heavy loading (flooding). The operator also cannot select which of the 3 effluent pumps (1 spare) to run in case of a breakdown.
2. Of the three effluent pumps, one is out of commission (a bad bearing), one is operating but leaking badly, and the last has been repaired, but cannot be selected to operate.
3. One old borrowed alum pump is operating with no spares. The alum draws particulates from the water as it passes through pre-treatment. This coagulation, as it is called, is vital in highly turbidity situations.
4. The D1 chlorinator is not working; no chlorine is being fed in D1 zone.
In summary, water drawn from the South Llano River could not be cleaned properly before being fed into the membrane units.
Initial Assessment of Membrane Plant
1. Flow of only 450 gpm from each of the two CMF/membrane units in an alternating configuration for a total flow leaving the plant of 450 gpm. Flow should be 695 gpm with units operating in parallel.
2. Acid Cleaning in Place (C.I.P.) of membranes could not be performed because of blockage in chemical feed line. This results in both units being fouled.
3. Many individual membranes are leaking; leading to failed air hold tests (normal is 1 psi/min loss).
4. No chlorine is being fed in D1 Zone, which means sand and membrane filters have biological growth on them.
5. One air compressor/dryer unit (2/1 spare) is out of commission and has been for some time.
6. Unit 2 membrane has apparently been shut down for some time after having its good membranes removed and placed in Unit 1 to replace bad membranes.
7. Water storage tank levels were set incorrectly.
8. Screens (2/1 spare) in front of membrane plant are suspect. Two strainer baskets are out of the units and sitting on the floor. Screens are important to keep sand coming from the pre-treatment plant and damaging V.F.D. valves, and membranes. In addition #1 strainer has a broken backwash arm.
9. Drying beds (2/1 spare) - one drying bed seems to be nearing its holding capacity and the other has been dug out with a front end loader. It is probable that this digging has damaged or destroyed the special liner in the bed.
The state will require an integrity test at least and replacement/installation of new liners if necessary. Also, the piled up sludge from drying beds must be disposed of in a landfill certified to accept this kind of waste.
(Note: the drying beds are used to dispose of backwash material from the pre-treatment and membrane plants.)
Actions Taken Since Arrival on September 2
1. Changed CMF's (membrane units) from alternating to parallel operation for a total now of 700 gpm.
Flow through the plant cannot be increased to full (1,400 gpm) because the one operating pump in pre-treatment makes only 700-750 gpm. All American Pump has been called to make repairs on non-operating pretreatment pumps.
2. Set tank levels to normal. Roundtop and Link Mexico tanks are filled manually pending repairs by Neltronics. Bluebonnet leaks so badly that it can be filled only halfway.
3. Got the acid C.I.P. working (had bad pressure regulator) and performed acid wash on unit 1.
4. Got D1 chlorine working (loss of vacuum repaired) and began feeding maximum permissible chlorine to "burn" its way through dirty/fouled filters.
5. Performed chlorine C.I.P. on unit 1 and acid C.I.P. on unit 2.
6. Sonic tested units 1 and 2 to produce a filter profile of leakage on a scale of 1 to 10. Unit 2 has 26 membranes of 2 or greater, with four 10s. Unit 1 has 20 with 8. (Note, the higher on the scale, the more leakage is occurring.)
7. Did chlorine C.I.P. on unit 2.
8. On September 6, All American Pump removed pre-treatment effluent pump for repairs. Without operating effluent pumps, there is no flow to the head tank, which feeds the membrane plant. If one should bypass the pre-treatment plant altogether, this would be problematic in times of high turbidity.
9. Cleaned floor of spilled chemicals in membrane plant.
The membrane plant is not designed to operate with turbides going on the filters. The pre-treatment plant is very important in keeping the membranes functioning through a period of flooding and extending the life of the membranes. The pre-treatment plant is capable of producing less than 1.0 NTU (turbidity) water even in high turbidity from flooding when operated by a competent operator.
The City of Junction should immediately undertake a search for a "B" (at least) TCEQ-licensed operator with real world experience. This person could then train a "C" operator and get her/him certified in a maximum of two years, with David Teel and Joe Tomlinson filling in part time with their existing certificates/licenses until then. No one in the city can currently operate the pre-treatment and membrane plants in a proper manner.
Both the pre-treatment and membrane plants have been operated with a complete disregard/or routine maintenance and even routine housekeeping. This culture must be changed.
It is essential not to lose the redundancy that is built into the pre-treatment and membrane plants. Fix things as they break down and return to operating primary pumps and other equipment as soon as possible, leaving backup/redundant equipment ready to be used when needed. Employees without the proper qualifications and licenses should not be permitted to work on the plant and access to the plant should be limited to those with a need to be there.
Take pride in this water plant, it is a good one (state of the art when constructed and first brought on line).
Permit operation of the plant by only qualified operators, keep a good supply of spares, repair broken pumps promptly, and keep the plant clean, and it will serve Junction for many years to come. Otherwise, it will only be a manner of time before the plant fails again and, depending on the harm caused, it may take considerable time, not to mention cost, to bring it back online. There is also the possibility that irreversible damage could be done.
As I leave the plant, it is now operating at the following level: 700-750 gpm, which is a total of one million gallons daily, an amount adequate to meet Junction's daily requirements based on historical usage.
To keep the plant operating and to bring it back to normal operation, the City needs to do the following in priority order:
1. Get a qualified plant operator on site immediately.
2. Return all three pre-treatment plant effluent pumps to operating and return membrane plant to full flow (two million gallons a day).
3. Ensure that individual membranes are tightened and operating at "air hold" results of less than 1 psi/minimum loss.
4. Pull the sand screens and ensure the strainer baskets are installed and clean.
5. Check the head tank for sand buildup and clean if necessary.
6. Repair computer in pre-treatment so it is operational.
7. Remove unmarked chemical barrels in membrane plant and obtain new ones that are properly labeled and NSF approved.
8. Obtain adequate alum feed pump and at least one spare for pre-treatment plant.
9. Find an operator from a city that operates a membrane plant (Del Rio) to come and train current city operator (David Teel?) on how to prepare the C.O.J. monthly operating report for submission to TCEQ. Training should take only a day.
10. Get spare Bluebonnet pump operating.
11. Clean up spills of chemicals immediately.
12. Engage team of specialists from Siemens, or its successor, to replace damaged membranes in a timely manner.
13. Fix drying beds promptly.
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