Challenge
The 27th Street Interceptor project is intended to reduce flood risk in the Five Points neighborhood and at selected downtown Denver, Colorado intersections. the 27th Street Storm Interceptor project is a large-diameter storm drain project designed to relieve drainage and flooding issues in the Five Points and Curtis Park neighborhoods and the RiNo Art District in the City and County of Denver (Figure 1). Before constructing this interceptor, stormwater runoff would drain to the South Platte River at the over-burdened 36th Street Outfall, causing significant flooding during storms. This flooding significantly impacted residences, businesses, and light rail.
Three tunnels were excavated from 10 feet to 12 feet beneath highly congested roadways and Regional Transportation District (RTD) light rail tracks. One 114 LF tunnel beneath Welton Street and the RTD tracks used a 78-inch-diameter fiberglass reinforced polymer mortar (FRPM) carrier pipe installed as a single pass in clayey sand materials improved with SoiLok grout injection.
Solution
Nicholson Construction Company was contracted by BT Construction with the task of stabilizing soils beneath a light rail transit system and above the tunnel bore of a 78-inch diameter tunnel. No track settlement could occur during the tunnel excavation beneath the RTD light rail tracks.
Design & Execution
Nicholson Construction Company designed and executed the ground treatment by injecting SoiLok 20 permeation chemical grout to stabilize a 12ft x 25ft x 40ft block of soil under the RTD light-rail tracks.
Bore Logs
Bore logs within the grout treatment zone indicated the tunneling contractor could expect soil conditions with high fines content between 23-26% passing through a #200 sieve.
Why SoiLok?
Construction Company chose SoiLok 20 as the chemical grout to be injected into the silty, clayey soils over sodium silicate and ultrafine grouts due to its very low viscosity of 1-2 centipoise.
Primary Applications
- Curtain grouting
- Soil treatment and stabilization
- Tunnels (subway, water, utility, etc.)
- Storm sewers and box culverts
- Below-grade parking decks
- Retaining walls
SoiLok is an extremely thin 2-component liquid resin that, when injected into soil forms a hard, cement typestructure, its strength is derived from the material (soil conditions) it permeates. SoiLok is a soil binding system (asubterranean grout) used to stabilize and bind loose soil or sand, stop underground water flows, and seal weeping seawalls or other below-grade structures.