The Vine is a new luxury apartment community located in Laurel, Maryland. The four-story, 539,000 square foot residential complex caters to renters with high-end tastes both indoors and out: exterior amenities include a resort-style swimming pool, outdoor four-seasons space with a fireplace, grill stations, and an extensive landscaped pathway system that connects each outdoor courtyard and the adjacent Maple Lawn community, shops, and restaurants.
Site development necessitated the design and construction of three segmental retaining walls, all built with the Keystone Compac® III wall system. The total area of the walls is 10,437 square feet. The large wall is 720 feet in length with the height ranging from 3 to 14 feet.
ECS Mid-Atlantic, a geotechnical engineering firm in Hanover, Maryland, designed the retaining walls. The large wall is a cut wall installed along the property line to allow for the construction of a drive lane in an area with a 14-foot grade change. A soldier pile lagging wall was first constructed, with the Compac segmental retaining wall (SRW) then installed in front of it as a facing wall. Geogrid reinforcement for the SRW was looped at intervals around adjacent horizontal pipes of the lagging wall, with the ends of each section secured above and below the units. Geogrid is installed in this manner when there is not enough room to excavate.
Keystone Compac III in the granite color blend was specified by ECS when it was determined that a soldier pile wall was the best type for the site conditions. The choice of using an SRW and Keystone Compac for the facing came down to aesthetics, a major factor for the owner, and cost considerations. Hasan Aboumatar, PE, the ECS project engineer, commented that the design of Wall 1 “was a challenge due to its proximity to the property line and the utility lines in front of the wall. Utilization of Keystone Compac III blocks as a facing for the wall to complement the adjacent buildings and garage provided a very cost-effective solution.”
Compac III is a structural wall system. It is lighter weight than comparable structural block and has a shortened tail design that makes it easier to handle. A unit is 12 inches deep with a face width of 18 inches and height of 8 inches. Units weigh between 67 and 89 pounds, depending on the local manufacturer, face style and aggregates. They vertically interconnect using high-strength pultruded fiberglass pins and have cores that are designed to be filled with crushed stone to provide additional mechanical interlock and internal drainage.
Compac units have been approved by 27 state highway administrations. York Building Products, Frederick, Maryland, manufactured the Compac III system for this project. Installation was performed by Griffith Brothers, Inc., a landscape company in Fallston, Maryland.