Newland Street Pavement Settlement

Monday, January 1st, 2024 by Jorge Figueroa

Challenge

Located in the City of Fountain Valley, CA, Newland Street is a four lane, asphalt paved road with bike lanes and concrete sidewalks. Significant pavement and sidewalk settlement had occurred along the northbound lane of Newland Street just south of the Ellis Avenue intersection. An approximate 65 linear feet of pavement and sidewalk showed as much as 4.5 inches of settlement, which required the area to be cordoned off until repairs could be performed. A 78-inch diameter stormwater drainpipe with an invert depth of about 10.5 feet runs along the approximate centerline of the northbound lane in the distressed pavement area. There was concern that settlement of the stormwater drainpipe was the cause of the pavement settlement; however, a camera inspection of the drainpipe interior showed no structural damage or signs of settlement. A geotechnical investigation identified 3 feet of fill above peat deposits to depths of about 9 feet below the pavement. Loose to medium dense sandy silt was observed below the peat. Options for remedial repair provided in the geotechnical report included removal of the peat soil and replacement with engineered fill or partial removal of the peat soil (to a depth of 4 feet) and placement of geogrid layers and engineered fill. The City of Fountain Valley obtained quotes for the proposed remedial options; however, a lower cost solution was preferred and there were concerns regarding the excavation shoring requirements and the length of time for repair.

Solution

The City of Fountain Valley contacted Saber to provide a scope of work and costing for deep soil improvement and pavement lifting using PolyLevel ® polyurethane injection. PolyLevel can be injected below the pavement and sidewalk at various depths. Once the two parts are mixed, a chemical reaction converts the liquid urethane components into an expansive, strong, and rapidly setting foam material. In its foam state, PolyLevel is extremely light, with different formulations weighing between 2 to 4 pounds per cubic foot (pcf). Given the ability to perform the repairs in a short period of time without excavation needed and a significant reduction in cost over other remedial options, PolyLevel foam injection was selected as the preferred solution. With a typical compressive strength of 60 to 70 pounds per square inch (psi) and a free-rise density of about 4 pcf, PolyLevel PL400H was specified for the soil improvement and pavement/sidewalk releveling. The Saber scope of work included PolyLevel PL400H injections at various depths of 3, 5 and 7 feet on a 5-foot grid pattern within an approximate 1040 square foot plan area. Based on the presence of peat soils, 50 pounds of PL400H was proposed to be injected at each depth interval. One-half inch diameter conduits were driven to the required depth to facilitate the PolyLevel injection. The PolyLevel was injected with a system pressure of 1200 psi and product temperatures of about 95 degrees. During the PolyLevel injection, ground surface movements were monitored with manometers and string lines established at the required lift elevations. PolyLevel injection quantities were recorded at each location with an average of 33.7 lbs. of PolyLevel installed at 163 injection ports for a total of 5,486 lb. The soil strength improvement after PolyLevel injection was evaluated with dynamic cone penetrometer (DCP) testing prior to and after treatment. The results of the DCP testing show a significant soil strength improvement of the peat soils from the PolyLevel treatment. At the area of largest settlement, the pavement/sidewalk elevations were restored to within ¼ inch of the proposed finish elevations. The PolyLevel injection was completed over a four-day period and the roadway/sidewalk was returned to service immediately afterwards.

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