In May 2026 a California city opened four bids for rehabilitating three wells against an engineer’s estimate of $175,000. The bids came in at $136,557, $144,215, $260,000 and $566,515. Six days before bid day, an addendum had added brushing, swabbing, airlifting and insulation (megger) testing to the scope, but no lines to the bid schedule. One bidder priced the added work on a modified schedule of its own; the other prices do not show whether it was included.
A spread of four to one is not a market. It is a scope that four contractors read four different ways. The contractors are rarely the problem: the document they bid from is. This note is about writing that document so the bids can be compared line by line and the result can be measured when the work is done.
Why rehabilitation bids come apart
The public bid packages we read show the same four causes again and again:
- Pay units that are not defined. One city’s bid form asked for a lump sum per well while its specification paid for the same work by the hour, in 15-minute increments. A bidder could reasonably price either.
- Scope added without bid lines. Work described in the specification or an addendum but missing from the schedule gets priced inconsistently or not at all, and comes back later as a change order.
- Unknowns deferred to change orders. Leaving possible casing and screen damage to a “change order request,” as one package did, invites each bidder to guess how likely it is and to price, or not price, the risk.
- Permits assigned to nobody. Who enrolls the discharge, who samples it, who pays for the tanks. When the scope is silent, some bidders carry it and some do not.
And behind all four sits a fifth: no definition of done. A scope that never says how the result will be measured cannot be bid on the result, so it is bid on guesses about effort.
Start with the definition of done
Before any bid lines, write down how the district will know the rehabilitation worked. That means three things in the scope:
- The baseline. The well’s specific capacity history, construction record and most recent video go into the bid package. Bidders price better when they can see the well.
- The same test before and after. A step test at the same stated rates and durations, before the work and after it. The Water Replenishment District of Southern California’s guidance on specific capacity makes the point that each test must use the same time frame to be comparable. How to read one is in step-drawdown or constant-rate test.
- Process endpoints, not a guaranteed recovery. None of the California specifications we read set a guaranteed percentage of recovered capacity, and there is a good reason not to: the formation, not the contractor, decides how much comes back. What the scope can require is that the work continue to a measurable endpoint. One city required development until sand content measured below 1 mL/L in an Imhoff cone; another required flushing until pH returned to a stated value and the discharge ran clear.
The bid schedule
The pay unit should follow what varies. Work whose size the district can define is a lump sum; work whose size the well decides is hourly with an estimated quantity; discrete events are priced each; and what nobody can know is an allowance or a unit price for discovered conditions.
| Work | Pay unit | Why |
|---|---|---|
| Mobilization | Lump sum, capped | One city capped it at 10% of the total bid, which stops front-loading |
| Pull and reinstall the pump | Lump sum | A defined task |
| Video survey | Each | Before, between treatments and after |
| Brushing, bailing, swabbing | Hour | Effort depends on the well |
| Dual-swab airlift, development | Hour | The same; usually the biggest hourly line |
| Chemical treatment | Lump sum per cycle | Lets the district buy a second cycle at a known price |
| Neutralization, tanks, disposal | Lump sum | Tied to a named discharge route |
| Test pump and testing | Lump sum plus hour | One 2023 schedule carried 88 hours of well testing |
| Disinfection | Each | One per event, with the retest included |
| Standby and owner-directed work | Hour | Kept separate so it cannot hide in other lines |
| Discovered repairs | Unit price | One schedule priced well repairs per linear foot |
| Replacement pump | Allowance | When its make and size are not known yet |
Two rules keep the schedule honest. Every item of work in the specification appears on the schedule, and every addendum that adds work adds a line. And the specification says, for every hourly item, what starts and stops the clock: whether setup counts, whether standby for the district’s decisions is paid, and whether downtime for the contractor’s equipment is not.
Chemicals and wastewater
Chemistry and water are where scopes are most often vague and where the regulatory exposure is.
- Products. Chemicals must be certified for drinking water use under NSF/ANSI 60, with the product data submitted before use.
- Neutralization happens at the surface. Spent acid and chlorinated water are pumped to tanks and treated there, never neutralized in the well. Say so.
- The discharge route is named in the scope, stream by stream: clean development water, turbid water, spent chemicals.
- Somebody holds the permit. California’s statewide general permit for drinking water system discharges, Order WQ 2014-0194-DWQ, covers well development, rehabilitation and testing discharges, and its coverage can include work done by contractors on the water system’s behalf. It limits residual chlorine to less than 0.019 mg/L before a receiving water and sets a 100 NTU turbidity action level for these discharges. The packages we read split the duty three ways: in one, the district held the permits and did the monitoring; in another, the contractor obtained all permits at its own expense; in a third, the contractor submitted a waste discharge plan ten days before work, with sewer discharge capped at 100 gpm. Any of the three works. Silence does not.
Disinfection and return to service
A rehabilitated well is a repaired well, and it does not go back into service on the contractor’s say-so.
- California’s well standards require a water supply well to be disinfected after repair or work on the pump, and their suggested procedure calls for at least 50 mg/L of available chlorine standing for 24 hours (100 mg/L where a repaired well must return to service quickly), then pumping to waste and a bacteriological sample.
- Title 22 requires a repaired well to be sampled for bacteriological quality before use. A positive result means disinfecting again under AWWA C654, resampling, and the State Board’s approval before the well returns to service.
- Title 22 also requires an amended permit before a source is changed in a way that could affect the quantity or quality of supply. Whether a given rehabilitation crosses that line is a question for your district engineer at the Division of Drinking Water, asked before the work, not after.
Write the retest into the disinfection line, so a failed sample is the contractor’s cost to repeat, not a change order.
What the district gets at the end
The scope’s last section lists the deliverables, and payment for the final item waits on them: the videos in a stated format, the daily logs, the chemical quantities and contact times, the development and discharge records with disposal receipts, the before-and-after test data at the stated rates, the reinstalled pump’s test, and the bacteriological results. A fuller list, for drilling and pump work as well, is in what a water district should get from every contractor.
What to do with this on Monday
- Put the well in the bid package: construction, specific capacity history, last video.
- Write the test protocol before the work items: rates, durations and who runs it, before and after.
- Build the schedule from the table above, and check that every sentence of work in the specification has a line.
- Name the discharge route and the permit holder for each waste stream.
- Make the deliverables a condition of final payment.
Quick answers
What should a well rehabilitation scope of work include?
The well’s baseline data, a before-and-after test protocol at stated rates, the work items with defined pay units, chemical and wastewater requirements with a named permit holder, disinfection and bacteriological sampling before return to service, and a list of deliverables tied to final payment.
Should well rehabilitation be bid as a lump sum or by the hour?
Both, by item. Defined tasks such as pulling the pump are lump sums; work whose extent the well decides, such as swabbing and development, is hourly with an estimated quantity; and unknowns are allowances or unit prices for discovered conditions.
Who is responsible for discharge permits during well rehabilitation in California?
The scope should say. The statewide general permit for drinking water system discharges can cover rehabilitation discharges, including work by contractors on the water system’s behalf; districts variously hold the permit themselves or assign it to the contractor.
See every rehabilitation on your wells with its scope, its cost and the tests before and after. Request a walkthrough →
Sources
- City of Rohnert Park. Well Nos. 33, 35 and 40 Rehabilitation: specifications, Addendum 3 and bid tabulation. 2026. Source for the engineer’s estimate, the four bids, the addendum and the modified bid schedule.
- City of Banning. Invitation for Bids, Well Redevelopment and Repairs. 2020. Source for the lump-sum bid form against hourly payment terms, and the Imhoff cone development endpoint.
- City of Oxnard. Bid tabulation PW 23-98, Well 20 Rehabilitation. 2023. Source for the mobilization cap, the 88 hours of testing, separate standby lines and per-foot well repairs.
- Soquel Creek Water District. Main Street Well technical specifications. Source for the pump allowance, the district-held discharge permit and the pH flushing endpoint.
- Beaumont-Cherry Valley Water District. Well No. 3 bid package. 2019. Source for contractor-obtained permits and hourly pay terms.
- City of Redding. Special Provisions, Enterprise Well 10 rehabilitation. 2026. Source for the contractor’s waste discharge plan and the 100 gpm sewer limit.
- Jordan Valley Water Conservancy District. Well cleaning specification. 2023. Source for the prohibition on neutralizing in the well and NSF/ANSI 60 products.
- State Water Resources Control Board. Order WQ 2014-0194-DWQ. 2014. Source for coverage of rehabilitation discharges and contractor work, the 0.019 mg/L chlorine limit and the 100 NTU action level.
- California Department of Water Resources. California Well Standards, Part II and Appendices. Source for disinfection after repair or pump work, and the 50 and 100 mg/L disinfection procedure.
- California Code of Regulations. Title 22, section 64583 and section 64556. Source for bacteriological sampling before a repaired well is used, and permit amendments for source changes.
- Water Replenishment District of Southern California. Technical Bulletin: Specific Capacity, Part 1. 2005. Source for testing on the same time frame each time.
Every link above was retrieved and read on 2026-09-26. Paid standards are named by designation so you can check them against your own copy.