Juneau officials propose two-mile HESCO barrier and LID to protect Mendenhall Valley homes ahead of 2025 season

Juneau City and Borough officials on an evening in January outlined a plan to install temporary HESCO flood barriers along roughly two miles of the Mendenhall River to protect homes damaged in recent outburst floods. City Manager Katie Kester and Chief Engineer John Bohan said the work would be paid for through a Local Improvement District (LID) that preliminarily assesses $6,292 to each of 466 properties, with a 10‑year repayment at the 4.78% interest rate set by city code.

The city presented the proposed Phase 1 alignment — from Marion Drive to Rivercourt Way — as a constructible short‑term flood‑fighting project intended to reduce the chance of repeated, severe inundation in the valley before a long‑term solution can be designed and permitted. “We need to keep the water in the river,” Chief Engineer John Bohan told residents during the meeting, summarizing the immediate goal of the barriers.

Why it matters: Officials said Phase 1 would protect 314 of the 322 homes the city recorded as damaged in the August 2024 outburst flood. Staff and the U.S. Army Corps of Engineers emphasized that the HESCO system is a temporary, deployable flood‑fighting measure intended to buy time while a separate, Army Corps General Investigation (GI) study looks at permanent options.

What the barriers are and how they would be used: Bohan and Army Corps representatives described HESCO barriers as wire‑mesh, fabric‑lined baskets roughly 3 feet wide by 4 feet high, sold in roughly 15‑foot sections. Units can be stacked and placed in multiple parallel lines; three stacked units would provide about 12 feet of barrier height. The city described site preparation, bank armoring in vulnerable locations, inlet/outlet pipes through the barriers with check valves, and use of larger “super‑sack” sandbag segments at some locations to allow controlled drainage or emergency openings.

Studies, modeling and permitting: The city has contracted Michael Baker International (MBI) for hydraulic and hydrologic (H&H) modeling. Bohan said the model will simulate river behavior with and without the Phase 1 barriers and help identify upstream and downstream impacts; the city expects initial model runs in late February. Officials noted the project requires multiple permits, including from FEMA, the Army Corps and state agencies, and said the permitting and design work will continue through the spring.

Short term vs. long term: City staff and Army Corps speakers emphasized parallel paths: (1) HESCO deployment as a short‑term, five‑to‑10‑year measure to reduce near‑term risk; and (2) the Army Corps’ General Investigation (GI) study to evaluate and recommend long‑term alternatives (for example, channel changes, lake management or levees). Nate Rumsey, deputy engineering and public works director, said a $1,000,000 participation agreement with the U.S. Forest Service is intended to help accelerate studies and data collection that will inform the GI.

Costs and the LID process: City Manager Katie Kester said the assembly initiated the neighborhood meeting under Ordinance 20,240 and amended an original 50/50 cost split so the city bears roughly 60% and the LID 40% in recognition that mapping and modeling cannot yet capture every property that may benefit. The city gave these key financial details: the preliminary assessment is $6,292 per benefited property (466 properties), payable over 10 years at the code‑required 4.78% interest rate; the assessment cannot increase under current city code; the charge becomes a lien on the property and travels with the property; and assessment payments appear as a line on property tax bills once final costs are certified after the project". Kester told residents that any written objection must be received by the end of the public hearing on Feb. 3, 2025, and that the ordinance would become effective March 3 if approved.

Other funding and contingencies: Staff said the city continues to seek grant funds; Clincott and HIDA (referenced in the meeting) had identified about $750,000 in grant funding under consideration. The city budget includes a $500,000 contingency to reinstall or restore obstructions (sheds, fences, decks) that must be moved for barrier placement. Rumsey also noted language in recent federal continuing resolutions that could provide up to $20,000,000 for a GI study, but city staff said the specifics (amounts and timing) were not yet available.

Community concerns raised: Residents pressed officials about downstream impacts, channel cutting or dredging, a permanent levee at Mendenhall Lake, property values, and the fairness of the LID and interest charges. Officials repeatedly said the H&H model will quantify upstream and downstream effects, and that Army Corps investigators will review long‑term ideas (including channel modifications and lake treatment) as part of the GI study. Staff acknowledged the borough hazard mitigation plan is out of date (2009) and said a contractor has been hired to update it; they said that update will be necessary to make the community eligible for some mitigation grant programs.

Installation and operations: CBJ staff said the city will control installation because the barrier system must be continuous and certified; individual homeowners will be free to do additional, private flood‑proofing on their own properties but may not independently install the HESCO segments forming the main line. The city said deployment will include training by experienced installers from Flood Defense Group (Keith Anderson) and support from Army Corps personnel; the city also plans concurrent work at multiple sites to try to meet a summer installation schedule if the LID and permits proceed.

What officials said they cannot promise: Staff and Corps representatives told residents there is no absolute guarantee the barriers will be completed before the next high‑risk season, and they described continued emergency response and evacuation planning as essential even if barriers are installed. Officials said the HESCO deployment is not intended to allow residents to stay in place during an outburst flood; they said advanced warning and evacuation remain part of safety planning.

Next steps: Michael Baker’s initial H&H runs are expected in late February; the LID public hearing is Feb. 3, 2025 (written objections must be received by the end of that hearing); and the ordinance would take effect March 3 if the assembly finalizes it. City staff said they will continue working with the Army Corps, U.S. Forest Service and federal delegation to pursue GI study funding and long‑term mitigation options.

The meeting closed with an extended Q&A in which residents repeated concerns about downstream consequences, property‑value impacts, dredging and the timing of a long‑term fix; officials said those concerns will be part of the modeling and the Army Corps’ GI process.