Retention or detention? Write the right pond maintenance bid

What is the difference between retention and detention maintenance?

The useful bid distinction is permanent water versus temporary storage. A wet pond keeps a pool between storms. A dry detention basin releases its stored runoff through its designed outlet and normally has no large permanent pool. Extended detention deliberately holds runoff longer for treatment. These operating differences change which surfaces your crew can reach and what vegetation it should maintain.

The facility name is only a starting point. Do not turn the owner's word retention into a construction detail. Identify the facility from its approved drawings, outlet arrangement, normal water elevation, and operation and maintenance plan, abbreviated O&M. A dry basin can also contain a small permanent micropool. One puddle does not establish the facility type.

Write the verified facility description beside the asset number: dry extended detention with a micropool, for example. Then attach the service map. If the owner wants every bank cut like lawn but the planting plan shows a protected aquatic bench, resolve that conflict before estimating. The bid needs an agreed work boundary and an agreed finished condition.

Which documents should you read before pricing?

Request the approved drainage and planting plans, available as-built survey, O&M plan, maintenance agreement, latest inspection report, and previous cleanout records. On public work, add the solicitation, site schedule, pricing form, and every issued addendum. Record the document dates and revision numbers in the estimate. Missing information belongs on the clarification list.

Build a worksheet with one row per basin and separate columns for the required task, quantity, frequency, method, acceptance record, and person authorizing extras. Trace each instruction to its document. Where a drawing and a maintenance schedule disagree, ask for a written resolution through the agency's stated question process. Do that while the answer can still reach all bidders.

A maintenance guide is useful background. It cannot establish this contract's acreage, legal responsibilities, or payment unit. Philadelphia's current pond guidance, for example, focuses maintenance on removing sediment and debris and preventing outlet clogging. Its recommendations help you ask better questions; the actual project documents establish what you are offering to perform.

Who owns the maintenance obligation and who can approve work?

Confirm the responsible organization before addressing the proposal. Ask for the maintenance agreement and a contact authorized to order work. A parcel owner, homeowners association, property manager, and public agency can have different roles. Put the buyer, site contact, inspector, and emergency contact into separate fields and verify authorization for each request.

Stow, Ohio, provides a concrete local example: its pond maintenance page assigns residents responsibility for bringing applicable stormwater facilities on their private property into compliance. It also publishes separate dry and wet pond checklists. That establishes an owner obligation in Stow; it does not establish the agreement or inspection schedule for another jurisdiction.

On agency work, identify who releases each work order and who accepts the completed visit. On private work, establish a spending limit and approval route. Keep a written record when the person requesting a repair lacks authority to approve its price. Resolve ownership or access disputes before scheduling equipment.

What should you measure on the bid walk?

Measure service surfaces, not the blue shape on a map. Separate mowable upland, basin floor, planted buffer, aquatic bench, and open water. Count inlets, outlet structures, forebays, gates, and locations needing hand work. A single acreage price hides the difference between riding a mower across firm turf and carrying cut vegetation up a bank.

Walk the equipment route with the proposed machine dimensions and operating limits in hand. Record the clear gate width, turning space, unloading area, surface condition, and distance from staging to the work. Mark the places where you could inspect an outlet from stable ground. Treat water entry, boat work, and entry into a riser or vault as separate methods requiring assessment.

Photograph existing ruts, bare areas, damaged fencing, unstable banks, and blocked structures. Price an agreed initial cleanup separately or record that the owner will complete it before recurring service starts. An opening condition record keeps the first annual visit from absorbing years of deferred work.

• Identify every basin and structure on the service map.
• Measure mowing, hand trimming, planted buffers, and water areas separately.
• Check equipment access, unloading space, haul routes, and locked gates.
• Locate sediment markers and available survey reference points without disturbing them.
• Record inaccessible features and the method needed to inspect them.
• Photograph existing damage and agree on the opening condition.

How should the routine scope change between wet and dry ponds?

Carry the same basic inspection framework across both facility types, then change the work zones and methods. Separate a visual inspection from physically clearing a structure. State whether clearing is limited to debris reachable from stable ground, what removal quantity is included, and what requires another crew or work order.

Wet pond vegetation needs a mapped prescription. Mark what stays, what gets selectively removed, and where the crew may work. Philadelphia's maintenance guidance specifically excludes the aquatic bench and buffer from its mowing and trimming recommendation. Copying a lawn scope across those zones would miss that distinction. Use the approved planting and maintenance documents for the actual boundary.

Define a visible result for each task: litter collected, specified access clear, designated vegetation maintained, and exceptions reported. Do not promise restored storage capacity on the strength of a clean-looking bank. That claim needs measurements against the approved design.

How often should the contract require service?

Use the facility's approved requirements and the solicitation to establish frequency. Break the calendar into routine vegetation visits, scheduled inspections, event inspections, and corrective work. Those are four different demands on the crew. A monthly grounds visit does not automatically provide the required observation after a storm.

Translate after-storm wording into an operating instruction before bidding: what event triggers a visit, where rainfall is measured, who dispatches the crew, how soon it must respond, and what happens when access remains unsafe. Ask how repeated storms are counted. Establish whether the contract pays for each event or expects them inside a fixed annual fee.

Include a return visit when the required drawdown observation cannot be made during the initial inspection. For a wet pond, identify the reference elevation used for pool observations. Write a weather deferral and notification process for mowing. The owner should receive a record of why work was delayed and when it will be reassessed. Avoid guaranteeing that every calendar visit can use the same equipment.

Should dredging and structural repairs be in the annual price?

Include them only when the contract defines them well enough to estimate, or requires an explicitly priced allowance. Otherwise, propose separate assessment and authorized corrective work where the procurement permits that structure. EPA's wet pond guide distinguishes routine tasks from sediment removal requiring specialized labor and equipment, and from structural inspection and repair requiring qualified professionals.

For sediment, request the cleanout trigger, survey method, removal footprint, target elevation, liner limits, and payment quantity. Specify whether the unit is in-place cubic yards, truck volume, or scale weight. Do not convert between those units without an agreed basis. Ask who arranges material characterization, receiving-facility acceptance, water management, hauling, and restoration, then price each assigned task.

For embankments and outlets, carry observation and notification in the routine scope. Ask for a qualified assessment when the crew finds settlement, seepage, erosion, damaged pipe, or established trees affecting the embankment. Do not add an unreviewed repair method to a mowing order. Changing an outlet opening or lowering a spillway is a design question to resolve with the responsible professional.

When a bid form combines all maintenance into one unit, request clarification before submission. An exclusion in a cover letter may conflict with that form. Decide whether you can price the required risk after the agency answers. An unmeasured dredging obligation can be a reason to pass.

Worked annual bid: a defined dry basin scope

Anvilfield research models a typical one-year basin account. The case uses one established dry basin with a two-acre service footprint, all approved for mowing, and a site walk confirming access for the proposed equipment. Existing defects and backlog are resolved before service begins.

The case uses 12 planned visits with two workers for three clock hours each. Each visit includes loading, round-trip travel, mowing, trimming, an accessible inlet and outlet check, ordinary litter collection, unloading, disposal travel, and the visit report. That is six worker-hours per visit and 72 annually. This production rate is achievable on the measured site, with no separate return inspections required by its documents.

Use a loaded labor cost of $38 per worker-hour, including wages, payroll taxes, benefits, and workers' compensation. Equipment costs $95 per visit, including the truck, trailer, mower, trimming tools, fuel, maintenance, and ownership costs, with no labor included twice. Disposal costs $20 per visit for up to four 33-gallon bags of ordinary litter; larger debris is separately authorized.

The case uses $900 allocated annual office overhead, a $384 cost reserve fully spent during the year, and a target 15 percent operating margin before income tax. The case uses no applicable sales tax, bond premium, permit fee, financing charge, or renewal-year obligation for this typical package. The base excludes chemical applications, water entry, sediment removal, structural repairs, and event visits; each needs separate authorization. Replace every input with the actual contract conditions before using the method.

Can you reuse that price for a wet pond?

Rebuild the quantities and methods first. In an alternative sample site, the same two-acre footprint consists of 1.2 acres of mowable upland and 0.8 acre of permanent pool and planted bench. The areas total two acres, but only the upland belongs in the mowing takeoff. Measure the shoreline work separately and identify the plants to retain.

Obtain an aquatic specialist's scoped price if the required work exceeds your crew's methods or qualifications. State whether that price includes mobilization, selective removal, collection, disposal, reporting, and any required follow-up. Leave unresolved treatment or sediment work unpriced until its basis is established, if the bid instructions permit that approach.

Do not reduce the dry basin number by the percentage of open water or apply a generic wet pond multiplier. The original three-hour visit input no longer describes the work. Replace it with an estimate for the actual zones and methods, then rebuild overhead and margin. On a mandatory lump-sum procurement, obtain the missing information before deciding to bid.

What does a real public wet pond solicitation include?

Austin's RFP 6300 MAS3007, Aquatic Vegetation Maintenance at Wet Ponds, is a historical scope example. The official notice shows it closed, with responses due December 2, 2025, and an award recommendation attachment dated January 15, 2026. It was closed when checked November 4, 2026.

The original package prices routine maintenance per square foot of pond area. It specifies at least three regular maintenance visits annually, at least 90 days apart, and calls for before-and-after photos where applicable. Section 11.2 requires those photos, an Application Tracking Log, and a Wet Pond Maintenance Tracking Form before an invoice is issued; section 12 sets invoicing requirements. Those are this procurement's requirements, not national service intervals.

Include photo, log and report preparation in the labor budget. Read the current agency package and all addenda before pricing a similar contract; the original Austin package alone is insufficient to reconstruct its final amended terms. Use the notice to locate the attachments, then reconcile the service boundary, payment unit, and acceptance conditions. To locate comparable public pond work, PorchRocket's Bid Control brings city, county and school bids together; read the current maintenance scope before reusing any unit price.

Which treatment and access limits need their own scope?

Chemical treatment needs a defined target, product, application method, responsible operator, and applicable approvals before it receives a price. EPA explains that pesticide label requirements and applicable National Pollutant Discharge Elimination System, or NPDES, requirements operate independently. An aquatic-use label alone does not establish discharge-permit coverage.

Check the current permitting authority. EPA's permitting page states that its 2026 Pesticide General Permit replaced the 2021 permit on October 31, 2026. EPA issues that permit only in its specified jurisdictions; other authorized programs issue their own permits. Ask the relevant authority which coverage applies to the actual proposed discharge, and verify applicator credentials separately. Do not reuse an expired federal permit reference from an old bid template.

For access, define the included method as work from stable ground unless another method has been assessed and priced. Keep water entry, boats, submerged retrieval, and confined-space entry out of an ordinary grounds allowance unless the contract expressly requires and prices them. Establish a safe-work assessment and qualified crew before assigning those tasks.

For excavation, ask the owner and reviewing authorities to identify the applicable disturbance, water-management, disposal, and restoration requirements. Allocate responsibility for obtaining approvals and paying fees. This guide cannot establish those obligations without a location, proposed method, and actual permit documents.

Scope wording that a crew can actually use

A weak line says maintain both ponds as needed. A usable line identifies basin numbers, mapped zones, tasks, visit quantities, methods, documentation, and extra-work authority. Keep the wording consistent with the agency's pricing form. A carefully written scope attachment helps only if the procurement accepts it.

For the typical dry basin budget, a proposed scope reads: Provide 12 scheduled visits to Basin D-1 during the contract year. Maintain the mapped two-acre mowing area and collect up to four 33-gallon bags of ordinary litter each visit. Observe listed inlets and the outlet from stable ground, clear only agreed reachable loose debris, and submit the dated visit report with photographs. Report inaccessible or defective components to the named owner representative.

Follow that with a separate authorization paragraph: Storm response, extra debris loads, sediment removal, treatment, and repairs require a written order describing quantity, method, price, and completion record. Identify an emergency notification contact and any response work already required by the contract. Establish how unused allowances and added locations will be handled.

On public bids, ask for amendments to ambiguous requirements through the procurement process. Do not conclude that adding your preferred limits changes the agency's terms. If the required scope remains broader than the work you priced, revise the estimate or pass before submitting.

What to document

Tie each report to a basin and work order. Use repeatable photo positions so the reviewer can compare conditions. Show the inlet, outlet, spillway, relevant embankment faces, and areas where work occurred. Record anything that could not be inspected, why, and who was notified.

Keep observation, action, and acceptance in separate fields. Outlet obscured by water is an observation. A request for a specialist inspection is an action. Owner approval of a completed task is acceptance. None of those fields should silently become a certification that the entire basin meets its design.

Agree on the report format and delivery route before the first visit. Keep measured removal quantities, receiving tickets where applicable, treatment records, unresolved defects, and approval history with the same asset. Budget the time needed to produce a complete record.

Common mistakes

• Pricing the entire parcel acreage when only mapped service zones belong in the bid.
• Treating permanent water as a blocked dry basin without checking the approved design.
• Including every storm visit in a fixed fee without estimating the response obligation.
• Calling all aquatic vegetation weeds and pricing its removal without a planting prescription.
• Selling restored storage capacity without a survey or defined cleanout elevation.
• Leaving travel, report preparation, and disposal time outside the production estimate.
• Presuming a proposal exclusion overrides mandatory public bid language.

Bid release checklist

Have the estimator and the person dispatching the crew read the same scope before release. If they describe different visits, reconcile the estimate now. Confirm the visit schedule with dispatch.

Standards and references

Sources checked November 4, 2026. EPA's December 2021 dry pond fact sheet and February 2009 wet pond guidebook provide technical background. The older guidebook expressly presents maintenance guidance rather than federally required maintenance solutions; its old cost examples are not used here.

Stow supplies the local ownership example, Philadelphia the service-zone example, and Austin the closed procurement example. EPA's current pesticide pages supply the permit-transition and label discussion. Apply each source within that stated scope. Obtain the actual site's approved documents and current agency instructions before turning this worksheet into a binding offer.

Units and bid terms

Use the same units in the takeoff, price schedule, work order, and invoice. Keep worker-hours separate from crew clock hours and sediment volume separate from truck capacity. Expand the unit on the bid form if its abbreviation could be read two ways.

Worker-hour

One worker for one hour; a two-person crew working three hours uses six worker-hours.

Service area

The mapped area assigned to a specific task, which may differ from parcel area or water surface.

In-place sediment volume

The measured deposit before removal, distinct from loose truck volume or disposal weight.

Unit price

The offered price for the contract's defined quantity unit and included work.

Allowance

A stated budget or quantity for defined work, with authorization and payment rules agreed in the contract.

Related field guides

Use the technical pond guide for facility components and the estimating guide to build the cost worksheet. The recurring maintenance guide helps plan the route and visit calendar. Where the site includes planted treatment cells, grading, disturbed ground, or native vegetation, carry those scopes into the review using the relevant guides below.

Methodology

Counts, prices, work rates, schedules and outcomes in typical cases are inputs to the Anvilfield research model. Calculations use the stated scope, formulas, cost inclusions and exclusions. Cited public records and technical documents support their attributed facts. Named case records, dates and outcomes are scenario inputs; cited public records retain their source attribution.

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