Improving Soil Stability of Flood Control Culverts Under Amtrak Rails with Injection Grouts-Paper

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The City of Meriden, Connecticut, installed two overflow culverts beneath active Amtrak tracks to help reduce chronic flooding from Harbor Brook. The project required jacking 73.5-inch-diameter steel casings through loose, silty sand with only about five feet of soil cover, making ground stability critical to protecting the railway.<br /><br />The original plan specified sodium silicate grout. However, groundwater and the soil’s high fines content raised concerns about its performance. The project team selected AV-100 acrylamide grout for its low viscosity, ability to permeate fine soils, adjustable set time, and suitability for long-term soil stabilization.<br /><br />Steel sheeting and soldier piles were installed beside the tracks. Injection pipes were driven through holes in the sheeting, and grout was applied ahead of the casing and from within the advancing tunnel. Because site temperatures were around 90°F, potassium ferricyanide was added to extend the grout’s set time to approximately two minutes, allowing deeper soil penetration before curing. About 35 gallons of grout formed a stable but workable soil matrix that could be hand-mined as the casing advanced.<br /><br />The steel casings and HDPE carrier pipes were installed successfully without disrupting Amtrak operations or compromising the supporting soils. The project was completed in summer 2020. The case demonstrates how controlled acrylamide grouting can stabilize loose, water-bearing soils for shallow trenchless installations beneath active railway infrastructure.

Keywords

Meriden Connecticut

Harbor Brook

overflow culverts

Amtrak tracks

flood mitigation

acrylamide grout

soil stabilization

trenchless installation

steel casings

groundwater