Mountlake Terrace planning commissioners review engineering manual updates; staff to recommend council action

The Mountlake Terrace Planning Commission on Dec. 22, 2025 reviewed proposed updates to the city’s Engineering Development Manual (EDM) and related sections of the Mountlake Terrace Municipal Code and heard staff’s recommendation to forward the package to the City Council for action.

Lucas Crot, who presented the EDM and accompanying code changes, told commissioners the packet had been distributed later than planned and that this session was intended as a high-level review. "Staff recommend we recommend approval to the planning or to city council," Crot said, and outlined a schedule that includes additional commission review on Jan. 12 and Council consideration in the first quarter of 2026.

Why it matters: staff said the changes are intended to remove outdated or conflicting regulations, consolidate standards into a single reference (MTMC chapter references to the EDM), and clarify application thresholds so applicants and staff rely on consistent criteria. Key proposed changes highlighted in the presentation would affect driveways, street dimensions, stormwater billing and permitting thresholds.

Major proposed changes and details

- ADU stormwater billing: The draft would define accessory dwelling units (ADUs) as one-half of an Equivalent Residential Unit (ERU) for stormwater billing and capital facility charges; current practice uses impervious-area calculations that staff said are inconsistent.

- Minor excavation and permit thresholds: Staff proposed adding thresholds to avoid requiring permits for very small amounts of earthmoving. Crot described the change as aligning permitting with how the city has been handling routine, small disturbances.

- Plan-review and bond consolidation: Multiple plan-review standards and several separate bond/maintenance-bond references would be consolidated under a single civil performance-bond section (1535) to reduce conflicting code cross-references.

- Driveway and driveway-approach standards: The draft clarifies on-site driveway widths and sets minimum on-site driveway widths at roughly 12 to 20 feet depending on parking configuration, while setting driveway-approach maximums equal to the stated minimums to protect on-street parking.

- Local access street cross-section: The manual proposes reducing local access street widths from 36 to 32 feet curb-to-curb within a typical 56-foot right of way; staff said that would preserve two travel lanes and two parking lanes while helping accommodate denser development without taking additional private land.

- Stormwater thresholds and lookback: Stormwater requirements would use a three-year lookback (similar to the building code) so phased projects are evaluated cumulatively for impervious-area triggers (staff cited examples where two near-threshold phases would combine to exceed trigger levels).

- Utilities, pavement cuts and terminology: Chapter 7.6 would add language requiring undergrounding to the nearest pole if a pole is within 50 feet; chapter 7.11 revises a pavement-cut moratorium to permit cuts on recently paved streets provided an overlay is ground and replaced 50 feet each way; chapter 24 proposes changing "sanitary sewer manhole" to "sanitary sewer maintenance hole" for gender-neutral terminology.

Questions from commissioners centered on practical impacts: whether the narrower local cross-section accounts for dedicated bike lanes (staff said bike lanes were not included and that bicycles would share lower-speed local streets), how driveway aprons and intersection clearance are handled (staff pointed to Chapter 11 and said the traffic engineer provided input), and whether reduced right-of-way dedications could increase buildable area for developers (staff said additional width across lots can materially affect project feasibility by providing space for utilities and improvements).

Staff and building officials also noted the EDM’s role in consolidating prior guidance so that residents and applicants will be able to find standards in one place rather than consulting multiple code sections. "You'll see a lot of the fingerprints from items that you've seen before, with the housing action plan and middle housing," said Matthew, the city’s building official, describing coordinated work across departments.

Next steps: Staff asked commissioners to review the full manual — which Crot described as roughly 500 pages of standards and referenced documents — and return detailed questions at the Jan. 12 meeting. Crot said staff plan to present a formal recommendation to the City Council in early 2026 and pursue an open-record hearing and Council action in March.

Procedural items: the commission voted by voice to excuse Commissioner Morgan from the Dec. 22 meeting and approved the Nov. 24 meeting minutes as presented. New Commissioner Chris Finch briefly introduced himself during miscellaneous business. The commission adjourned after the director’s report and holiday greetings.

The Planning Commission will revisit the EDM and proposed code amendments in its first meetings of 2026; staff asked commissioners to submit specific questions during their review so staff can provide additional details and examples at the January meeting.