During a real estate transaction, civil engineers walked a 1400LF run of 14′ diameter multiplate tunnel running underneath a strip center in Asheville, NC.
A previous inspection had indicated impending section loss of the pipe due to corrosion, and had recommended grouting of incidental voids, but no work had been performed at that time.
The pipe, which had up to 20′ of cover, bypasses a large stream, and runs under 200LF of building footprint, the main entrance roadway, two out-parcels, and ties into an NCDOT box culvert to discharge.
Significant debris were present in the pipe, and access was exceptionally difficult. Because dewatering was not practical, all work proposed had to be performed under flow.
CJGeo proposed polyurethane backgrouting using plural component CJGrout material, specifically CJGrout 35NHV61.
CJGrout 35NHV61 is a hydroinsensitive, moderate mobility grout designed for backgrouting in wet environments, and is certified for potable water contact.
Despite a bear wandering into the pipe during repairs, CJGeo crews successfully backgrouted the pipe to address piping and erosion outside of the structure over a period of two weeks. More than 40,000 pounds of CJGrout 35NHV61 were needed to underseal the headwall structure and pipe.