Location: Glenn Arm, MD
Completed: 2020
Value Class: <$300K

The Client is Maryland’s largest natural gas and electric utility, delivering power to more than 1.3 million electric customers and more than 680,000 natural gas customers in central Maryland.

Project Details


Initially, TAI was hired by the Client to submit a Retaining Wall Repair Design but shortly after the design submission, the Client asked TAI to execute wall replacement as well. TAI acted as General Contractor to provide oversight, coordinate and manage construction. However, TAI did self-perform the fabrication and installation of the guardrail portion of the project.

TAI’s structural engineer visited the site to survey the collapsed section of retaining wall approximately 20’ x 4’ at the Client’s facility in Glen Arm, Maryland. The existing wall was constructed with stone and mortar and situated at the top of a steep hillside with very poor accessibility. The portion of the wall that had failed was near the center with drainage from above concentrated near this area causing the failure. After inspection, it was determined that logistics of repairing only the 20’ of failed wall made it infeasible, and approximately 70’ of stone retaining wall would need to be removed and replaced.


The replacement design comprised of a newly poured concrete footing, poured concrete stem wall with drainage stone, drain tile and weep holes to relive hydrostatic pressure. The exposed portion of the wall was finished with a stone complementary to the existing wall that was to remain. The slope below the wall was modified to reduce the risk of erosion from the concentrated flow below the new weep holes.

TAI supplied all labor, materials, installation, tools, management, and safety implementation to complete the replacement of the retaining wall including the following:

  • New wall to be located along existing wall.
  • Installed super silt fence for sediment and erosion control and stabilized construction entrance.
  • Modified existing fencing to provide for temporary security barrier and to provide for sufficient working space.
  • Demolished and hauled offsite existing mortared stone retaining wall.
  • Excavated for six-foot wide footing.
  • Laid excavation back toward existing structures/buildings at 1:1 slope.
  • Furnished and installed reinforcing steel for footing and wall.
  • Constructed new concrete footing with keel.
  • Furnished and installed all formwork as necessary to construct approximately 70LF of wall.
  • Furnished, conveyed and placed 4,000PSI concrete.
  • Stripped forms, executed clean-up, and cured wall.
  • Furnished and installed stone veneer and cap.
  • Furnished and installed drain stone backfill and 4” perforated PVC drainpipe.
  • Backfilled footing and walls with imported structural fill and compact.
  • Furnished and installed approximately 100LF of new security fencing to match existing.
  • Restored all disturbed areas to pre-construction condition.
  • Fabricated and Installed approximately 70’ of industrial style aluminum guardrail along top of wall.

The project delivered on time and under budget. The regrading and improved drainage provided better control of storm water and the elimination of issues related to erosion. The Client was provided with a safe and functional retaining wall meeting their goal to seamlessly blend in with the remaining facility.

Services Provided:

  • Project Management
  • Structural Engineering


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