Services /
Conveyance & crossingsCulvert Design & Conveyance Sizing in Whatcom & Snohomish
A culvert is rarely a standalone question. It is sized by what drains to it, what happens downstream of it, and what the reviewing jurisdiction expects to see in the calculations. AXE handles culverts as part of the conveyance design on land-development projects across Whatcom, Skagit and Snohomish Counties, from the Bellingham and Arlington offices.
What we design & deliver.
- Culvert and conveyance sizing with supporting calculations
- Downstream conveyance connections for detention and treatment
- Grading and profile detail at the crossing
- Plan sheets a reviewer can act on
- Coordination with the wider stormwater and utility design
Sized for the whole system
The pipe is the easy part. What matters is the contributing area, the downstream capacity and the standard your jurisdiction applies, which is why culvert work sits inside the drainage design rather than beside it.
Built for the reviewer
Calculations are prepared in the form the reviewing agency expects, so the submittal is assessed on its merits instead of being returned for the wrong supporting work.
Honest about scope
If what you need is a failed driveway culvert dug out and replaced, that is contractor work and we will say so rather than sell you an engineering package you do not need.
What people ask before they call.
Do I actually need an engineer for a culvert?
Often not. Replacing a failed driveway culvert like for like is usually a contractor job and does not need a stamped design. You need an engineer when the crossing is part of a development, when the jurisdiction asks for sizing calculations, or when what drains to it is changing because of what you are building.
How is a culvert sized?
By what drains to it and what the receiving system can take, not by what is already in the ground. We work out the contributing area, check the downstream capacity, and size the crossing against the standard your jurisdiction applies.
Does this come with the rest of the drainage design?
Usually, yes. On most projects the culvert is one element of a conveyance system that also involves detention, treatment and the downstream connection, and designing it on its own tends to create a problem somewhere else.
Which jurisdictions do you work across?
Whatcom, Skagit and Snohomish Counties and the cities inside them, from the Bellingham and Arlington offices. Standards and reviewer expectations differ between them, which matters more on conveyance work than most people expect.
What do you need from me to quote it?
The parcel number, what you are building, and a sense of what crosses the site. That is usually enough for us to tell you whether a culvert is engineering scope on your project, and to put a written fee in front of you.
Often paired with.
Core service
Civil Engineering & Stormwater Design
Site plans, grading, utilities, and drainage design for classic civil engineering projects including commercial & multifamily developments, short plats & large subdivisions.
Fixed-fee · Approval guaranteed
Residential Stormwater Drainage Design
Standalone Stormwater Drainage Design for single-family building permits or land disturbance permits.
Civil plan production
Drafting & Design
High-quality drafting, site exhibits, and preliminary evaluations to help you visualize and price a project before you commit.
Schedule a call today.
Whether you're planning a subdivision, a single-family home, a commercial site, or just trying to figure out what's feasible — we're happy to talk it through.