Lindon planning commissioners unanimously approve excavation for hillside home addition with geotechnical conditions

The Lindon Planning Commission on March 25, 2025, voted unanimously to allow excavation at 62 South Denali Circle so the property owner can open the site for a proposed three-story walkout addition, but only after meeting a set of conditions including geotechnical and geology reports and verification of water pressure and fire flow.

Planning staff presented the request as an excavation-only approval so engineers can fully observe subsurface conditions in the hillside overlay area before any construction beyond excavation begins. Mike Florence, a staff member who presented the application, said the lot falls within the city's Hillside Overlay because of slopes of 20 percent or greater and noted that the original subdivision review included a geotechnical study for the entire neighborhood but not for this specific lot. Florence added that a geotechnical firm (IGES) recommended excavating first and then returning with soils and geology reports for review.

The commission’s action approved only the excavation phase and attached eight conditions listed in the staff report. Conditions require that the geotechnical engineer’s recommendations in the IGES letter dated March 19, 2025, be followed; that a building permit and applicable fees be obtained for excavation only; that no work beyond excavation occur until the geotechnical and geology reports are submitted, reviewed by city departments and presented back to the commission; and that updated building plans incorporate the engineers’ recommendations. Other conditions require verification of on-site drainage, a written statement from the landscape contractor addressing vegetation mitigation, and compliance with the Canberra Heights Plat A subdivision notes and Lindon City ordinance 17.57 (Hillside Overlay District) and adopted interpretations.

Bryce McConkie, identified in the meeting as the building official, described technical steps the engineers will take. He explained that a standard test pit for groundwater is to three feet below proposed footing elevation and that the current proposal involves excavation down about 22 feet from the driveway grade to reach the proposed footing level. McConkie also noted the applicant is proposing a pool in the lower level, which will require roughly nine additional feet of excavation beyond the footing depth. "They're actually proposing doing a pool in there," McConkie said during the discussion.

Commissioners asked technical and location questions about the depth, foundation walls and how the excavation approach compares to typical test pits on undeveloped lots. One commissioner summarized the rationale: allowing full excavation adjacent to an existing structure lets the builders and engineers directly observe conditions rather than rely only on exploratory test trenches. The presenter and building official said the excavation approach shifts the immediate subsurface risk to the property owner and their consultants while allowing more certain engineering recommendations before additional work proceeds.

During the review staff also cited a subdivision plat requirement about fire protection and water flow: the Canberra Heights Plat A notes that a dwelling up to 9,400 square feet (Type V-N construction) is contemplated under the plat language tied to a 2,500 gallons-per-minute fire flow with 20 pounds-per-square-inch residual pressure, or an alternative approved by the building official. The applicant must verify water pressure and flow rates and submit that report to the city engineer and building official along with the required geotechnical and geology reports.

The applicant’s representative and the builder indicated they understood and accepted the excavation risk. In discussion before the vote, the applicant’s builder said, "It always falls on my shoulders," when asked whether he was willing to bear the risk of excavation.

A motion to approve the excavation, with the staff’s eight conditions as read into the record, carried unanimously. The commission did not authorize any construction beyond excavation; staff and the applicant must return with the geotechnical and geology reports and any updated plans for the commission’s further review and action.

The commission discussion also included brief questions about the lot’s location relative to nearby roads and about the subdivision’s minimum building site size; staff noted the lot meets the plat’s minimum building site requirement and does not encroach into the recorded aqueduct easement. The commission closed the item by directing staff to ensure the required reports and verifications are completed and presented at a subsequent meeting before any building permits for work beyond excavation are issued.