Hidden in Plain Sight: Solving a Septic Field with Landscape Design

This month we're highlighting a project that proves square footage isn't the measure of a good design challenge. Set high on the ridgeline of Mount Tamalpais with sweeping views across the Bay, the Pacific Ocean, and Muir Woods, this Mill Valley property is compact, but every inch of it required careful problem-solving.

At the heart of the project is a sculptural concrete stairway connecting the home's main deck to a detached ADU below. The architectural-grade concrete stairway is complemented by Ipe wood vegetable beds built directly alongside it, turning circulation space into growing space.

The stairway curves gracefully to meet the ADU, where an Ipe wood bench invites a pause before a second run of stairs continues up to a turf play area for the family's children.

The site's greatest constraint lived below grade: a hillside septic leach field, with distribution tanks positioned directly under the turf play area. Our team planted over and around the leach field so it reads as a hillside garden and we discreetly disguised the five access lids to the tanks below the turf (can you find them?), keeping the space fully usable for the family without sacrificing an inch of it to visible infrastructure.

It's a project that reflects what we do best: intelligent design solutions that work with a site's constraints, not against them.