Juneau officials outline temporary HESCO barrier plan, local improvement district and timeline for Mendenhall Valley flood protection

City Manager Katie Kester and Chief Engineer John Bohan told residents at a Jan. neighborhood meeting that the City and Borough of Juneau (CBJ) is pursuing a two-track flood response for the Mendenhall Valley: short-term flood-fighting measures using HESCO barriers and a parallel long-term study with the U.S. Army Corps of Engineers.

The short-term plan — described as a temporary protection measure expected to last up to a decade — would install HESCO fabric-and-wire flood barriers along a roughly two-mile segment from Marion Drive to Rivercourt Way. CBJ officials said that deployment is intended to protect the largest number of damaged homes ahead of the next expected outburst flood, and that hydraulic modeling and permitting must be completed before construction begins.

The HESCO barrier deployment and associated work would be funded through a local improvement district (LID) that the assembly initiated earlier; CBJ staff said the preliminary assessment is $6,292 for each of the 466 properties included in the district, with a proposed 10-year payment plan at a 4.78% interest rate and a 60/40 split of costs between CBJ taxpayers and assessed properties. City staff said objections to the LID must be submitted in writing by the end of the public hearing on Feb. 3, 2025, and that the ordinance would become effective March 3 if adopted.

Why it matters

CBJ stressed that long-term solutions will take years to study, design and permit. The HESCO deployment is aimed at buying time and preventing repeat damage in the near term while the Army Corps’ general investigation (GI) study and other long-term options proceed.

What officials described

- Short-term vs. long-term: Chief Engineer John Bohan said CBJ is pursuing parallel paths: (1) hydraulic/hydrologic (H&H) modeling and short-term “flood fighting” measures such as barriers or sandbag equivalents; and (2) a General Investigation study led by the U.S. Army Corps of Engineers to identify preferred long-term solutions. Deputy Engineering Director Nate Rumsey said CBJ secured a $1,000,000 participating agreement with the U.S. Forest Service to advance data collection and that a potential $20,000,000 federal allocation for GI work was included in recent supplemental legislation but details and timing are not yet specified.

- HESCO barriers: Bohan and Mike Rickards of the Army Corps described HESCO barriers as engineered, wire-and-fabric “overgrown sandbags” shipped in 15-foot sections and typically 4 feet high per unit; CBJ said configurations will vary by site and some stretches will be double- or triple-stacked to reach required heights. Drainage will be maintained using pipes placed through the barriers with check valves; CBJ staff said the installation team will design drainage and “super sack” overflow segments where needed to release trapped water safely.

- Phase 1 scope: Staff said the proposed first phase targets a two-mile segment from Marion Drive to Rivercourt Way and that the alignment was chosen to protect the greatest number of previously damaged homes. Bohan said Phase 1 is designed to protect 314 of the 322 homes documented as damaged in the 2024 event; staff said barrier heights are being set to exceed prior high-water marks but stressed the final heights will be informed by the H&H model.

- Technical study and schedule: CBJ has contracted Michael Baker International for H&H modeling; staff said the contractor will incorporate new aerial lidar and other datasets and that an initial run of mapping and modeling is expected in late February. Bohan and Rumsey said that information will show how barrier deployments will affect flows upstream and downstream and help prioritize further phases.

- Cost, funding and property impacts: Kester summarized what the LID would cover (permitting, bank armoring where required, barrier purchase and installation, site prep, drainage and a contingency) and said CBJ reserved $500,000 in the project budget for restoring or reinstalling obstructions removed during installation. Staff said four properties that require full armoring would be assessed an additional $50,000 each. CBJ said property owners will not be allowed to install individual HESCO segments themselves because the system must be continuous and certified; owners were told they may still deploy private, exterior flood protections on their own property.

Community concerns raised at the meeting

Residents asked repeatedly about downstream impacts, dredging or channel-cutting as alternatives, liability if a barrier fails, timeline and whether dredging or lake-level management (pumping or levees at Mendenhall Lake) could be implemented faster. Staff said those long-term or structural options are part of the Army Corps GI scope and/or require permitting that cannot be completed in time to reliably prevent another near-term outburst flood. CBJ staff acknowledged the risk of unintended consequences and said that the February H&H modeling is specifically intended to identify downstream or upstream impacts and to inform how Phase 2 should be prioritized.

Other notable points from the meeting

- Schedule and next steps: CBJ staff said permitting and design work will continue through the ordinance effective date; if the LID proceeds CBJ would begin site work and barrier installation as soon as permits and procurement are complete. The H&H model’s initial output is expected in late February; staff said installation is being targeted for the spring–summer period ahead of the typical outburst season, with July cited as a construction target if approvals and procurement proceed on schedule.

- Public process and objections: The assembly amended the original cost split to a 60/40 share favoring borough taxpayers; objections to the LID must be filed in writing by the end of the Feb. 3 public hearing to be counted. The certified mailing packet and an online objection form are available on CBJ’s flood response website, staff said.

- Responsibility for restoration: City staff said CBJ will be responsible for reinstalling barriers when a permanent solution is reached and for restoring obstructions that must be removed for installation; a reserve in the budget is intended to cover some of that work.

What remains unresolved

Officials said the H&H study will show whether the Phase 1 HESCO deployment changes flow patterns that shift risk to other properties; that modeling is the primary near-term data gap. Rumsey and Bohan said Michael Baker International is working on time-and-materials contract terms to expedite modeling and that the Army Corps’ GI work remains necessary to evaluate more permanent options such as channel modifications, dredging, lake-level control or levees on federal land.

How to stay involved

CBJ staff repeated the Feb. 3 public hearing date and asked residents to submit written objections if they oppose the LID. Staff also pointed residents to floodresponse@juneau.org and to the CBJ website for the presentation materials, the certified mailing packet and signups for emergency alerts.

Ending

City officials described the HESCO deployment as a temporary, emergency measure intended to reduce immediate flood risk while more time-consuming long-term studies and permitting proceed. The February hydraulic modeling results and the assembly’s public hearing on Feb. 3 were presented as the next critical milestones for residents watching whether the HESCO/LID proposal will move forward.