Thread by @shayshinecastle

Up now: Upstream detention at South Boulder Creek. This has been turned down 3X prior; OSBT just said no thanks. Presentation: www-static.bouldercolorado.gov/docs/Item_6A_-…

UGH, looking the least forward to this. Feels like we're just going through the motions, since OSBT already turned it down. Very unlikely council will do different.

Story: boulderbeat.news/2021/01/02/ups…

This was initially schedule for Jan. 5 but got pushed bc that meeting went too long. My notes from that meeting are as follows:

Council chose Variant 1 flood design June 16, 2020 bc "it was found to have the least environmental impacts, the lowest cost, and was identified to have the greatest probability of permitting feasibility through the various regulatory agencies."
boulderbeat.news/2020/02/29/bou…

(As staff wrote in notes to council)

Why are we calling it upstream? Because the plan would put most of the flood control features further upstream, collecting more water on CU's land and reducing impacts to open space.

When they approved Variant 1 design, council also asked for one more look at upstream detention - considered twice before in 2015 and 2018; OSBT asked for it again when it was revealed that flood structures would go in open space lands rather than U.S. 36 right-of-way

I prob have a link for that, but it's so hard to find. Sorry not sorry.

An advisory group was put together as part of this analysis: Staff, 2 WRAB members, 2 OSBT members, 2 Planning Board members, 2 council members

“The advisory group concluded that although an upstream alternative could be feasible, it does not perform better than the Variant 1, 100-yr design when considering the June 2020 comparison criteria, and substantial engineered structures would still be required on OSMP lands."

Staff analysis “demonstrated that an upstream option could provide similar flood protection to the Variant 1, 100-yr design but would be significantly more expensive and would result in greater overall environmental impacts, including substantial engineered structures on OSMP."

Upstream cost: $110M
vs. $41M for Variant 1 (which is the flood protection only; fill costs add ~$10M to that)
Fill costs for upstream option are still unknown

Upstream: Larger concrete dam, but no floodwall on open space
28 acres for embankment/flood wall (vs 10 for variant 1)
Overall smaller project footprint (52++ estimate vs. 64 for Variant 1)

“The upstream project requires a larger detention facility and additional infrastructure to meet flood mitigation goals.”

Upstream detention:
Would impact 61 acres of wetland (vs. 7.7 for Variant 1)
58.4 acres of prebles mouse habitat (vs. 3.9 for Variant 1)
7.1 acres of ute ladies tresses orchid habitat (vs. 2.5 for Variant 1)
$5.1M in environmental mitigation costs (vs. $1.3M for Variant 1)

Less direct impact to open space (3.5 acres vs. 5) but more indirect (45 acres v 0)
Indirect impacts = “fragmented” wildlife access or changes to groundwater flow that will change soil composition, hydrology and vegetation

Upstream also requires more complex dam safety review, per staff notes

OSBT on Dec. 16 recommended against it
“The Upstream Option, as analyzed, does appear to provide similar flood control for the West Valley as Variant 1, and increased flood control along South Boulder Creek north of US-36 ...

... and thereby would avoid the need for the Variant 1 floodwall on the OSMP State Natural Area. The Upstream Option has a smaller footprint on OSMP lands and slightly less foundation to bedrock requiring groundwater conveyance. ...

... However, providing this level of flood control requires construction of substantial structures some of which would have impacts similar to or greater than Variant 1 on OSMP habitats. Opportunity for riparian and floodplain restoration in the project area may be diminished.”

3 members of the public spoke at Nov. 18 public hearing; 5 at Dec. 16 decision

OSBT reaffirmed “environmental and other” concerns about Variant 1 — rejection of upstream is “NOT an endorsement” of Variant 1, they wrote

This is actually super interesting to me. OSBT has a very specific mission; they're honoring that while still recognizing that the city is working toward flood control as a goal/priority.

(Slight aside, but Young *just* criticized the Transportation Advisory Board for a narrow focus rather than looking holistically at everything the city is responsible for. Which is what OSBT did... in a way that honors its mission AND contributes to the convo)

Anyway, the only other thing in my notes is HOW. FREAKING. LONG. Boulder's been at this. I personally would have said since ~2015 in narrowing down design options, but per staff notes....

“The City of Boulder has been considering alternatives for SBC floodplain mitigation since 1973 … Between 2001 and June 2020, extensive community board and council engagement and technical analysis” to select design option.

That's 19 years in settling on a design. (Though I don't particularly think that's fair, given that studies and such were still being done in that time to decide WHERE to do flood control, not just what it should look like.)

"With infrastructure solely on the CU South property, we didn't meet the goals" for flood mitigation, says Brandon Coleman.

Coleman: There WERE reduced flows in other area waterways, but not the main flood impacts we're trying to mitigate here.

Tadeucci summarizing: Upstream detention would provide similar flood mitigation, but it would cost more and have more impacts to open space.

Curt Brown, OSBT chair, calling this an "investigation."

We recognize that it took additional time and resources, Brown says, but given new info in June about flood path, volumes, board "felt it was incumbent" to explore.

Brown: The analysis revealed it WOULD be possible to detain water entirely on the CU South property, "to make such a storage dam fully functional and meet flood control objectives," we'd need additional structures on open space.

"I believe when the city seeks regulatory approval" for the project, I think this investigation into upstream detention will "provide" additional evidence "of a good-faith effort" to explore all options, Brown says.

Permitting is going to be a bear. A dozen different agencies, each with its own interests. Very high bar for city to find a plan with the fewest impacts but still high efficacy.

That process will likely take a year+

Friend and Wallach thanking staff for their work.

Wallach: "I think these were important questions to look at and answer. The results are very dispositive. I think this is a matter of case being closed.'

I just want to say Wallach *didn't* sigh during this but he *did* sign earlier, so technically the Wallach Sigh-O-Meter is at 1, but I'm afraid to mention it in case the convo spontaneously turns uber serious again and I look like a dillhole for being silly.

Weaver: "I think everybody got an education on this project" through the process.

"This is a project that has life-safety benefit for thousands of members of our community," Brockett says. "Just want to get that out there."

Swetlik thinks this is a good time to clarify for the community what's ALREADY been done, what's been decided and what's still ahead.

Joe Taddeucci: "For us, this allows us to focus on a single alternative now and permitting and preliminary design for that alternative. ... It really represents a transition. In 2020, we were working a lot on flood mitigation ... "

"In 2021, the annexation and that process will be coming forward."

To summarize more succinctly: Flood stuff at CU South = done (from a city council/public process)

CU South Annexation = TBD

There are certainly ppl who don't want to see annexation and development. But that's what we're working toward. "We're working on a questionnaire that assumes that happens and what they would like to see" from an agreement, Taddeucci says.

Next council update: April.
TAB taking a look at CU South in Feb/March
I believe a council vote on annexation by mid-2021...?

That's all for this one. 5-min break before online petitioning and Holocaust/prairie dogs Part 2

@threadreaderapp please unroll.