DESCRIPTION

The Brookland Press Apartments project is a two-building apartment complex (Building A & B) with a four-story connecting corridor in Northeast Washington DC. Building A was constructed by renovating a former seven-story printing facility, while Building B is a six-story residential building with 139 apartments over a first-floor parking garage and was new construction from the ground up.

CHALLENGE

The soil conditions under both the connecting corridor and Building B presented a challenge for Douglas Development Corporation. When GEI Consultants, Inc (GEI) performed their subsurface investigation they found up to 20 feet of uncontrolled FILL was present on the site. This FILL was generally underlain by 10 ft of interbedded layers of medium dense clayey to silty sands and stiff sandy clays and silts under which the soil changed to medium dense to dense sands.

Building B, which consisted of two stories of concrete construction underlying four stories of wood frame, had column loads of up to 700 kips. GEI determined that the combination of the uncontrolled fill and the heavy column loads could result in excessive settlement of shallow spread footings. GEI evaluated several different foundation support options including Geopier Rammed Aggregate Pier® elements (RAPs), 60-ft deep Auger Cast-in Place Piles, and 40-ft deep Driven Concrete Piles.

SOLUTION

The design team ultimately chose Geopier RAP supported shallow spread footings for the new construction based on performance, price and schedule. Over 400 RAPs were installed to reinforce the uncontrolled FILL soils and minimize the risk of differential settlement. The RAP elements ranged in depth from 8 to 20 feet, and saved over 30% when compared to the cost of the deep foundations alternatives.