Thread by @shayshinecastle

OK, flood stuff up now. It sounds boring (and maybe is) but I found many interesting numbers in the packet. Presentation here: www-static.bouldercolorado.gov/docs/3D_2020_F…

The flood and stormwater master plan is being updated for the first time since 2004

Let's look at my notes from the packet, shall we? I got about halfway through before I had to take a nap today.

Stormwater and flood management utility funds come from user charges (a dedicated enterprise fund)
70-80% of revenue from monthly utility bills

Other revenue: Development fees (plant investment fees) Mile High Flood District, interest earnings
Allows bonds (debt) to be issued to pay for big projects

You might have noticed your water bills going up in the past few years as city undertakes some big flood projects and upgrades to its water/stormwater/sewer systems.

There are 8 big projects that need doing, $119-$152M cost
South Boulder Creek (Phase 1) $66-$99M (that's the big one we talk about all the time as CU South)
Upper Goose Creek: $24M
Gregory Canyon Creek: $10M
Fourmile Canyon Creek at 19th Street: $10M

Boulder Creek stormwater mgt: $4M
Four-mile flood mitigation / Broadway culvert: $3M
Bluebell Canyon Creek & King’s Gulch: $1M
Wonderland Creek stormwater improvements: $1M

Why so much flood stuff? Boulder is incredibly flood prone. There are 16 major drainage ways in the city.
13% of the city is in 100-yr floodplain, and 2,000 structures

Some flood history: Largest flood on record: 1894 (6 in rain; Boulder Creek 100-yr flood conditions; 1 death)
Boulder Creek flooded 1914, 1929
South Boulder Creek flood 1938, 1969
Sunshine Creek: 1906
Two-mile Canyon Creek: 1909 (2 deaths)

Bear Canyon Creek: 2007 (Table Mesa overtopped)
Fourmile Canyon Creek: 2011
September 2013: 19 in rain over 8 days (5-100-yr flows depending on location)

Here's a fun table showing those:

Boulder is often referred to as the most risky city in Colorado for flash flood. Insurance data underscores that point: Boulder has the most flood insurance policies in the state.

4,353 policies (as of Jan. 10, 2020)
Total insured coverage of $1,065,934,000
Premium costs of $3,540,676

Boulder has four flood zones, each with their own regulations

500-yr floodplain: 0.2% chance of occurring in any given year
100-yr floodplain: 1% of being equaled or exceeded in any given year.

Conveyance zone: Flood waters flow through without increasing depths, redirecting waters or adversely impacting land areas. Can be developed with some limits (can’t make flooding worse).
High-hazard zone: Greatest risk of loss of life. Should not be occupied by ppl during a flood

Some examples of development restrictions in 100-yr flood plain: No basements on homes and lowest floor has to be 2 ft above floodwater surface elevation; non-residential must be flood proofed on lower elevations and be automatic (no human intervention to trigger)

That includes automatic floodgates, such as at the Municipal Building. St. Julien Hotel and Alfalfa’s.

Development in 100-yr floodplain must also have sewer backups and no parking lots where flood water will be deeper than 18 inches, since cars float.

Staff showing some before/after photos of various flood mitigation projects. Fun fact: My most popular tweet ever is a video of the flood mitigation feature in my neighborhood at work, preventing overtopping of the Goose Creek.

It took 3 yrs to build. Three years of 7 a.m. construction starts and road closures. But that one day I saw it work = WORTH IT.

OK, back to some costs for flood/stormwater stuff:

Yearly expenses (+4% every year for inflation)
Local drainage improvements: $850K
Preflood property acquisitions: $660K
Storm sewer rehab: $630K
Transportation-related flood and stormwater improvements: $630K

Drainage maintenance/enhancement: $520K
Stormwater quality improvements: $190K
Greenways - lottery fund: $150K (no 4% increase)
Greenways - flood fund: $98K (no 4% increase)
Utility billing computer system: $100K (one-time cost)

Why property acquisition, do you ask? City sometimes buys properties in high-hazard zones (since ppl aren't supposed to live there anyway) and uses land for flood mitigation.

Recently, Boulder bought 744 University (2017) and 712 Pleasant (2019) along Gregory Creek.

It's an "opportunity-based" program, meaning they have a list of priority properties and buy them as the opportunity arises. (Not often)

Douglas Sullivan talking a little bit about that now, if you're following along with the video.

Gotta say, the passion from staff in talking about this stuff is palpable. I love when they nerd out over their jobs. Passion is contagious!

LOL slide 27 of this presentation is just a list of some of the city's master plans that are important to the stormwater/flood utility master plan.

Like the E. coli TMDL Implementation Plan

Boulder loves itself a master plan. I wonder how many we have?

There are 15 just on this slide

THIS master plan won't be finalized until mid 2022

This is a fun map: how much water each drainage way can convey. (Black = very bad)

Douglas Sullivan: "We have a lot of miles of drainage way that require some sort of improvement going forward."

Not every drainage way needs 100-yr levels of conveyance. It's all about what's around there (Homes? Businesses?) plus the grade of the drainage way, what it drains into, what drains into it, etc.

Remember when we talked about flood insurance earlier? Slide 32 shows how Boulder compares to other cities. We have nearly 10X the number of policies as Colorado Springs. We have 2X more than CO Springs and Denver combined.

Overall Stormwater & Flood Management Utility Budget = $15M/year

$6M operating / $9M for capital improvement projects

The Mile High Flood District helps fund our CIPs, up to 50%. Also pays for 100% of maintenance projects.

Of course, we help fund that through property taxes. In BoCo, .608 mills ($304/year for home worth $500,000)

District is currently funding:
CIP for South Boulder Creek, Gregory Canyon Creek, Fourmile Canyon Creek
Flood mitigation planning studies for Upper Goose Creek, Two-mile Canyon Creek, Skunk Creek, Bluebell Canyon Creek, King’s Gulch
Floodplain mapping study for Sunshine Canyon

For Boulder's CIP: $6.3M is for flood; $3.2M for stormwater

For flood projects, $2.1M is funded through cash and $4.2M by debt service

"The challenge is we have an old city that was developed before modern floodplain standards came into play," Director of Utilities Joe Taddeucci says.

Friend q: Are 100-yr projects the max we've ever done?
Yes, Sullivan says. Cities tend to do projects to that level if they can because of National Flood Insurance Program requirements.

You have to have flood insurance for homes with federally back mortgages in the 100-yr floodplain. If you do a project that takes homes out of that designated flood zone, then you don't need flood insurance for those homes.

Weaver: It's been 3 yrs since we did critical facilities ordinance (for things like hospitals, schools, etc. in the 500-yr flood plain) Is that common?
Katie Knapp: It's encouraged by the national program. We did ours in 2013.

Wallach: Is it correct that Upper Goose Creek is scheduled for $24M improvements in 2023?
Yes, Sullivan says. (Expounding on that) bc parts of it doesn't have ability to convey much water without flooding

"This requires a comprehensive piped" network starting at 19th/Alpine, Sullivan says.

It's about $15M in a pipe network and $10M to improve capacity of section behind Edgewood to 5-10-year conveyance level.

That will require bonds, Sullivan says in response to Wallach q.

Wallach: You show $40M in bonds for South Boulder Creek, but our cost estimates are much higher. Are you expecting money from Mile High Flood District, or is that number incorrect?
Sullivan: That's an incorrect number, based on old data.

That project now includes unanticipated elements, Sullivan says. Piped projects are easier to predict in terms of cost, so we don't expect Goose Creek costs to substantially change.

Wallach: How are these big projects going to impact customer's utility bills?

Ken Baird: Generally speaking, we have $66M project on South Boulder Creek. That would involve potentially 50% rate increase to storm/flood project line item.

With Upper Goose Creek at $24M, it will be about another 20% increase.

Wallach: Presumably if numbers go up, those numbers will go up commensurately?
Yes, Baird says.
Wallach: "So we're looking at very, very significant" increases.
Baird: Yes, in terms of percentage.

50% increase is $8/month on a typical single-family home, Baird says

Swetlik: "We have some critically underfunded life and safety needs and we had them before we lost $1 in $7 of sales tax revenue."

Keep this in mind as we go through financial strategy and budget, he says.

Sullivan: Boulder receives about half of the Mile High Flood District's allocation.

$1.5M, on average. They don't tell us what to use it on, Sullivan says. But it's cooperative work with them.

Sullivan getting into why it's hard to break down costs and benefits for projects.

The map we shared today is a great start to a convo about "what is realistic?" What can we build in the community?

We're pretty in the weeds, so I'm just listening.

"We will do our best as we scope the master plan to help council understand the interplay of these 16 drainage ways and what's realistic moving forward."

Brockett: Whatever you can include to give us and the community an understanding of "what's left." The map showed what level of implementation we have; it would be great to see what level we want to have.

That's the end of this one. Thankfully; they were getting over my head.

@threadreaderapp please unroll. Thank you!