Provo district engineers propose reconstruction and extra borings to stabilize Wasatch retaining wall

Engineers and the district’s contractor presented a reconstruction plan for the Wasatch retaining wall and asked the Provo School Board to authorize immediate repair work and subsurface testing.

Chris Hogan, president of Hogan Construction, and Tyler Lorser, principal designer at IGES, described a two‑step plan: finish reconstruction of the lower wall tier now — including geogrid reinforcement, chimney and blanket drains and an impermeable membrane near the top — and then perform additional borings and monitoring to determine if further work is needed. "The engineers have... agreed on this path forward, support this path," Lorser said during the presentation.

Hogan and IGES explained the technical fix: geogrid layers will be installed every 2 feet to interlock with compacted gravel backfill and a blanket drain system will tie into the storm-drain network. The presenters said the earlier wall used wood framing in places that no longer meets code and that the contractor who built the original wall is in the process of dissolving, which has added complexity to remediation planning.

To clarify sources of groundwater and soil variability, the team asked to drill four additional borings (two on the north side, two on the east side) and to add or convert piezometers or wells to monitor water before it reaches the wall. The consultants noted the borings would ideally be done during the school break around Thanksgiving and estimated two to three days of drilling.

On costs, presenters asked the board to approve part one as soon as possible and proposed a "not to exceed" approach that would cover raw hard costs; they said soft-cost management and coordination (which they estimated at roughly $300,000) would be absorbed by the designers and was not included in the immediate request.

The board asked clarifying questions about the extent of geogrid lengths (engineers said current grids are about 21 feet, exceeding the original minimums of 17 and 14 feet), backfill compaction, and whether additional concrete or regrading could help prevent future settlement. Staff confirmed potential mitigation steps including regrading the adjacent parking area, adding a cutoff drain and relocating some storm infrastructure while the site is open.

Next steps: engineers requested board authorization to proceed with part one reconstruction and to schedule the four additional borings and monitoring work; the board did not record a formal vote during the study session and asked staff to bring the purchase request language forward in the business meeting or a subsequent packet.

Provenance: topicintro: SEG 478, topfinish: SEG 941