Lot 304 Flood Mitigation
Dundalk Marine Terminal, Baltimore, MD

ADundalk Marine Terminal Lot 304fter three flooding incidents from 2009-2014 cost the Maryland Port Administration (MPA) and their tenants at the Dundalk Marine Terminal (DMT) Lot 304 millions of dollars in ruined inventory, something had to be done. The MPA turned to WBCM for the solution.

WBCM analyzed the existing storm drain system and quickly realized that 3.82 acres of impervious area flowed into a storm drain system that was a relic of the DMT’s history as a WWII-era airfield and quickly realized that Lot 304 needed an entirely new storm drain system.Dundalk Marine Terminal Lot 304

WBCM’s design was an innovative system that is designed to keep Lot 304 dry through a 500-year storm event. The centerpiece of the system is a massive 90-foot wide by 90-foot long by 12-foot deep, underground, cast-in-place concrete, pile supported storage vault that that can store 56,000 cubic-feet of stormwater runoff, treat it for water quality, and pump it 4,200 feet to Colgate Creek, a tributary of the Patapsco River.

Water quality treatment is achieved by channeling stormwater into a sedimentation chamber, which allows Dundalk Marine Terminal Lot 304solids to settle out, before flowing through a sand filter. The result is 100% treatment of the 3.82 acre drainage area, allowing the MPA to bank credits towards satisfying their
National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) permit and Total Maximum Daily Load (TMDL) requirements.

Water is discharged through 4,200 feet of 14-inch force main by two pairs of pumps. A pair of 5HP pumps are used during low-flow situations and, when storm flow increases, a pair of 35HP pumps kick in, discharging 1,700 gallons per minute. All four pumps are connected to a backup generator to ensure that flooding does not occur even in the event of a loss of power.

Since construction wrapped up in April, 2016, Lot 304 of the DMT has not had a flood event.

  • Owner: Maryland Port Administration
  • Size: 3.82 acres
  • Total Construction Cost: $4.12 million
  • WBCM Services: Marine Engineering
    Civil Engineering
    Environmental Water Resources