Purple Line. Montgomery and Prince George’s Counties, Maryland.

WRA managed the geotechnical efforts through preliminary design that included a subsurface investigation program that included SPT borings and laboratory testing of soil and rock samples. Preliminary foundation evaluations were provided for 40 bridge and over 70,000 LF of retaining walls that included mechanically stabilized earth, cast-in-place, soldier pile and lagging, and micropile and lagging retaining walls within limited right-of-way. Recommendations for the stabilization of the existing 50’ high slopes through Rock Creek Park were also provided. Evaluations of feasible design alternatives with cost and construction impacts were provided in Preliminary Geotechnical Engineering Reports. The data from the subsurface investigations were provided in a Geotechnical Data Report.

Subsurface investigations for the proposed 1000 foot long, Sequential Excavation Method (SEM) tunnel included SPT borings, sonic drilling, point load tests, packer testing in rock, pressuremeter testing, acoustic televiewer logging and extensive laboratory testing of soil and rock samples. The data collected along the tunnel was provided in a Geotechnical Data Report.