Provo City School Board members on April 29 heard technical findings and repair options after a portion of a mechanically stabilized earth retaining wall failed at Wasatch Elementary, and the district’s contractor recommended a staged repair focused first on drainage and local reconstruction.

The update came during a study session presentation led by Chris Hogan, president of Hogan and Associates Construction, who said the district and contractor have prioritized safety and continuity of education while investigating the cause. “Our very top priority is the safety of this the students, the staff, the public in and around that area, and making sure that the education continues, you know, not interrupted,” Hogan said.

Engineers from IGES and geotechnical consultant AGEC described the site as having mixed native soils, large areas of imported fill and a clay layer that can trap water. Tyler Lercher, the retaining-wall designer from IGES, summarized why the team did borings and trenches: “the main purpose of these borings is to gather subsurface data… ground water would be something that you look for, but you’re also going to look for certain soil characteristics.” Jim Norquist of AGEC added, “Water goes where it wants to,” reflecting uncertainty about the water’s precise source.

Nut graf: The board was presented with a working technical explanation that the wall movement resulted after a previously dry fill zone became saturated by an unforeseen, relatively recent inflow of water; the saturation increased hydrostatic pressure and reduced soil strength behind the lower wall, producing outward movement and settlement above the failed section. The presentation laid out short- and longer-term repair options, costs and further tests the board may request before authorizing larger rebuild work.

Most important facts

- What happened: Contractor and engineers said the lower portion of a mechanically stabilized earth retaining wall pushed outward after water saturated the fill behind it, creating space that allowed the upper wall to settle.

- What investigations found: The team reviewed geotechnical borings and trenches (initial borings in Aug. 2020; additional borings in April 2022), performed compaction tests and pressure-tested utility lines; they did not find evidence of pipeline leaks or continuous groundwater in the original borings, but observed new seepage and saturation at the soil cut where the wall failed.

- Probable mechanism: Engineers said water is likely entering a relatively more permeable sand/gravel layer, striking a less permeable clay layer and then moving laterally to the wall face. Tyler Lercher (IGES) described the observed condition: water had “almost completely saturated” the fill soils and seeped out at the wall face, producing hydrostatic pressure that pushed the lower wall outward.

- Options and recommended approach: Hogan’s team recommended a phased response. The “base” option would rebuild the failed wall section and reinstate paving (presented cost: about $457,000). Additional measures include installing a back-drain behind the repaired wall (approximately $55,000 on the map shown), replacing the top rock/landscape with concrete (approximately $24,000), trenching farther behind other wall segments (approx. $136,000), or a full remove-and-replace of additional walls (additional approx. $781,000). The contractor recommended the intermediate, staged approach that reinstalls the failed wall segments with a full gravel blanket drain and extends targeted trenches as needed rather than performing the full large-scale rebuild immediately.

- Timeline and materials: Contractors said the immediate wall reconstruction work for the failed section would take weeks once authorized; a single-wall repair sequence was estimated at roughly two to three weeks for the wall work. They reported approximately 50 concrete facing blocks would need replacement on the failed section; most other blocks could be reused per the manufacturer’s guidance.

Board-level questions and follow-up actions

Board members pressed engineers about the water source and whether changes to nearby development, capped irrigation lines or storm-drain conditions could now be diverting water into the site. The contractor summarized on-site actions already taken: pot-holing and camera inspection of sanitary and storm piping (no leaks found), isolation and pressure testing of the fire-water line (no leaks), and excavation to expose saturated soils and the wall’s reinforcement (geogrid). Hogan said the contractor has downstacked the wall and trenched to expose the problem area to gather direct observations.

The board and team agreed on next steps short of committing to the most expensive rebuild option: finish the immediate lower-wall stabilization work to secure the site; continue testing and monitoring; and pursue additional borings and monitoring wells so the district can track groundwater or new seepage. Board members asked the district to obtain a third-party review of designs and records before approving larger, more-expensive work.

Selected direct quotes (attributed)

“Water goes where it wants to.” — Jim Norquist, geotechnical consultant, AGEC

“The main purpose of these borings is to gather subsurface data…ground water would be something that you look for.” — Tyler Lercher, retaining-wall designer, IGES

“Our very top priority is the safety of this the students, the staff, the public in and around that area, and making sure that the education continues, you know, not interrupted.” — Chris Hogan, president, Hogan and Associates Construction

Ending: immediate decisions and what’s next

No formal board vote was taken on repairs during the study session. The contractor was authorized to continue securing the site and complete the lower-wall work already underway; the board requested additional geotechnical borings, installation of monitoring wells and a third-party peer review of findings and proposed designs before committing to larger reconstruction spending. The district and contractor said they will return with updated costs and recommendations after those tests and reviews are complete.