CU South flood plan is full of holes
I’ve been studying the flood situation again, and it is becoming increasingly clear to me that (1) the proposed “100-year” detention pond for South Boulder Creek will not stop the areas that flooded in 2013 from being inundated again, and (2) the related Annexation Agreement that allows massive development on CU South is full of holes and should be repealed.
Let’s be straight about the 2013 flood. Much of Southeast Boulder is a floodplain, created by South Boulder Creek, Viele Channel and other local flows. Given climate change and the resulting stronger storms, even if a storm centers on the Eldorado Springs area and drains into South Boulder Creek, it is a virtual certainty that this “100-year” pond will overtop with some frequency; so the downstream area will be flooded anyway. But if the storm centers a few miles further north over Southwest Boulder, water will come down Viele Channel, completely missing the detention pond. Then the water will do just what it did in 2013 — run uncontrolled through the US 36 and Table Mesa intersection and flood much of the same area.
CU has refused to let Boulder build a pond big enough to handle a “500-year” event, even though CU gets 500-year protection for all its CU South development. (By the way, regarding the claims by some that CDOT won’ t let Boulder build a 500-year pond, open record requests have yielded no documents saying anything like that.)
Interestingly, after the 2013 flood, the Frasier Meadows retirement community, where many people were pushing the city for faster action, built berms, walls and flood gates around many parts of their property. The great advantage of such improvements is that they block water irrespective of its source. Some quick calculations suggest that far more structures might be protected using this approach for less money than by the inadequate pond. And the pond still has numerous uncertainties regarding receiving the necessary permits, legal agreement that the city’s flood fees can be used for this, and political consent to potentially putting off other city-wide flood work for decades.
Additionally, much of the 2013 damage was not from direct flooding, but from sewers and basement floor drain backups. The city is finally starting to re-line sewers. It should set up a large-scale program for homeowners to lower the cost of installing backflow preventers since they have a very high level of certainty of actually preventing damage. And an early warning system would ensure that people are not surprised as in 2013. As a reminder — the only deaths in 2013 were on a road west of North Boulder, not in Southeast Boulder.
To build this inadequate pond on CU’s property, the city council signed an Annexation Agreement with CU (negotiated in 23 arguably illegal closed-door meetings) that would allow CU’s development on the site to be almost the size of downtown Boulder. Bizarrely, this agreement could be changed by a bare majority of a future city council to further increase the amount of development, eliminate the height limit, end requirements for traffic mitigation and even change the zoning to commercial to allow CU to sell the property for a windfall, all without citizen approval.
As to the traffic issue, the Annexation Agreement is, once again, full of holes. The agreement is structured so that CU cannot proceed to the next “phase” of development unless the traffic limits are maintained, but the “phases” are determined by CU. The amount CU must spend for mitigation ($5 minimum per trip) does not rise with inflation. So, by the time this mitigation is required, it is virtually certain that CU’s EcoPass program, which all students and staff get anyway, will meet the agreement’s requirement. So, expect traffic to increase without any real limit.
Finally, there is no guarantee that the city’s design for the pond will pass muster. The pond relies on unproven systems to pass groundwater through the floodwall’s impervious foundation to maintain valuable wetlands on the downstream side of US 36. It also relies on a huge concrete -lined pit excavated below groundwater level to increase the pond’s capacity. This pit will also have to be maintained indefinitely, otherwise it will fill with groundwater and silt and be useless.
Of course, in the process, many of the irreplaceable natural areas in the floodplain will be gone, and we will all be the poorer. That is why almost 6,000 citizens signed a referendum giving us a chance this November to tell the council that this annexation needs to be rethought right from the beginning.
Steve Pomerance is a former Boulder city council member. firstname.lastname@example.org