PSDA.5:5.1 - Flood-pump alternatives beyond a purchase contest
In this illustrative case, the board needs a pre-season return for the next flood season. The inquiry distinguishes nominal capacity, deployment reliability, unequal service, and downstream consequences. The model account says that nominal permanent and mobile capacity can meet the assumed inflow when the stated units are operating, but mobile arrival under road loss is not yet supported. Reachable assistance remains a separate service concern.
The inquiry turns those premises into three candidate descriptions and one unfinished proposal for staging:
| Candidate | Different action being considered | Present use and gap |
|---|---|---|
| N — continue the present arrangement | Keep already authorized operation and maintenance; make no new capacity commitment. | A real baseline for comparison, not an assumption of adequate service or zero cost. |
| F — fixed-capacity change | Add fixed capacity with the necessary operating, staffing, and support arrangement. | A proposed whole change; direct engineering and service results must qualify its consequences. |
| M — mobile-reserve arrangement | Obtain mobile capacity together with its transport, deployment, staffing, and access arrangement. | Retained for inquiry; the road-loss deployment premise prevents an unconditional commitment claim. |
| S — unfinished staged proposal | The proposal would preserve a later capacity choice informed by an access or service inquiry, but its first intervention has not been specified. | Keep the construction question open: what should change first, and how would that permit the later choice? Specify that intervention and qualify its temporary provision, resource overlap, delay and recovery before comparing S as a distinct direction. Adding the benefits of F and M does not answer these questions. |
The property-protection and reachable-assistance concerns remain distinct. They lead the team to ask whether each whole arrangement serves both; they do not establish an approved priority between them. No candidate is dropped because its proponent dissents from the majority.
Return N, F and M with their stated limits, and retain S as an unfinished proposal with a named construction question. The supported comparisons remain usable at their stated scope. If commitment-ready options are needed, identify the missing premise for M and the unfinished construction and qualification of S. Keep those gaps visible without claiming that the usable set exhausts all possibilities.
A further construction round. Suppose the recipient now asks for a pumping arrangement that can be deployed on the isolated side when the bridge is closed. PSDA.6 separates that end from the proposed means “deliver the reserve unit by road”. Working backward through PSDA.8:4.2.1 gives another route: put a unit, a competent crew and their required supplies on that side before closure. The first combination borrows the crew of an existing fixed station. Testing it forward exposes an incompatible condition: operating both arrangements during the flood needs that same crew at both sites. This candidate cannot claim both services.
The team constructs L: pre-position a leased unit and supplies at a suitable local site, with a separately available crew and an agreed local activation arrangement. For this teaching continuation, assume that the responsible specialists have established site suitability, equipment and crew availability, the relevant operating permissions, and provision for the named flood duration; the cost fits the stated comparison budget. With those premises, the forward trace no longer depends on the bridge or double-allocates the fixed-station crew. L is a new comparison-ready alternative for the specified deployment result. Its cost, capacity, service distribution and other material consequences still need comparison; it is neither a selected investment nor evidence of actual performance. If the separate crew cannot be obtained, retain that exact gap or reopen the service formulation instead of silently restoring the double allocation.