Opinion: South Boulder Creek flood mitigation needs new minds doing new the thinking

Boulder just added a web page where the city states that it will start building the dam/floodwall for South Boulder Creek in October. No surprise to me, the projected cost went up another $10 million to $76.5 million since last year. (And that’s after spending something like $13 million on multiple re-designs to deal with issues that any intelligent person should have seen early on.)

Just to list off some of the many problems that this “downstream” design still faces: The half-mile-long concrete wall along U.S. 36 requires a drainage system to get groundwater under U.S. 36 so as to avoid killing off threatened species on both sides; this will require significant ongoing maintenance to keep from being jammed up with dirt, etc. The detention pond at the north end of CU South property will require a liner, so that it doesn’t fill from high groundwater levels in that area. And the liner requires a drain, so it can empty and isn’t filled by pre-flood rains. 

The road into CU South must go over the three-story high dam. CU’s whole property will be in the floodplain except where, per CU’s demands, the City must add tons of fill to keep CU’s buildings out of a 500-year flood. But downstream Boulderites are allowed only protection from 100-year floods, except those who will get flooded anyway by water coming down unconstrained Viele Channel and Bear Creek. By the way, Viele Channel will likely carry some of SBC’s flood water, so these folks are doubly threatened.

On its new web page, the city gratuitously jabbed at the citizens who sued the city over its inappropriate use of fees based on impervious surface of in-city lots when essentially all the SBC flood water comes from outside the city. The city staff says that this lawsuit will force the city to cash-fund the dam/floodwall over five years rather than issuing bonds so they could build it in three years, allegedly saving money.

But the city staff provides zero info as to why it would be significantly cheaper to build it in three years. And, even if that were true, the city could raise flood control fees by around $10/month/property for the three years, build it in the shorter time period, saving whatever that amount might be. Besides, if they really want to issue bonds, which could cost 5% or more in interest, they could use General Obligation bonds just by putting the issue on the ballot. But I guess they’re (legitimately) paranoid that they would lose at the ballot box.

Regarding the cost issue, I note that Frasier Meadows has made serious investments in floodproofing their buildings and underground garages. That, of course, reduces the potential benefit of the dam, which makes the cost vs. benefit ratio even worse. A friend pointed out to me that the city’s Capital Improvement Program Guiding Principle No. 8 states that capital programming should “maximize efficiency of investments demonstrated by measurable cost/benefit analyses.”

But of course, meeting this requirement would require actually doing a detailed comparative analysis of the various alternatives, which the city never did. The first obvious alternative to the current design is building the detention area upstream on the south-east portion of CU South, which was originally intended to serve that function. It would be way cheaper, have a larger capacity, be much more robust and less likely to fail and drain back directly into SBC rather than Viele Channel. 

The second alternative is floodproofing the 260 structures that are threatened, minus, of course, Frasier Meadows, which is already done. The costs would likely be far less: Even if the costs averaged out to $100,000 per structure, which is far above the cost for the city’s example building, for 250 buildings that would be $25 million total, about a third of the dam’s cost. To make emergency access/egress easier for the few hours a century that floods made the roads difficult, the city could buy a few Humvees with high-water equipment and give them to the fire department.

As to the costs, there was no info on any bidding process for the dam’s construction. I submitted an Open Records request, but don’t have the results yet. But I have very little confidence that it was bid out. Remember the sale of the Spruce Street parking lot, which the city failed to put out to bid, apparently because their consultant said that the solo offer they received was “above market,” an absurd statement on its face.

We really, really, really need some new blood running our city.