Horseshoe Baltimore is an urban two-story casino, and the second largest casino in Maryland with a 122,000-square-foot gaming floor. The multimillion-dollar facility features video lottery terminals, table games, and a World Series of Poker room.
Designing a stormwater management system for this site was challenging. The site contained brownfield contaminants such as aromatic hydrocarbons, heavy metals, fuel oils, and miscellaneous industrial chemicals. In addition, the site was located in a 100-year floodplain, and a high tidal water table was often within two to five feet of the existing ground surface. The development area was limited to existing building footprints and public roads, and subject to various restrictive regulatory overlays that limited design flexibility.
Stormwater management in Maryland is governed by the Stormwater Management Act of 2007. The Act’s goal is to apply stormwater standards on an equal basis for all sites and best mimic pre-developed conditions. The Act requires implementation of Environmental Site Design to the maximum extent practicable. Rainwater Harvesting was selected as the most effective Environmental Site Design practice for the Casino because it was possible to sequester nearly 100 percent of the principal indicator contaminant of urban runoff through “complete” collection and re-use of mandated ESD Treatment Volume.
Rainwater collected at the site is used for toilet flushing and irrigation. Contech worked with engineers from Colbert Matz Rosenfelt to provide the treatment systems and the mechanical controls for the system.
Runoff from the site is first pretreated using a CDS® hydrodynamic separator. The CDS hydrodynamic separator uses swirl concentration and continuous deflective separation to screen, separate, and trap trash, debris, sediment, and hydrocarbons from stormwater runoff.
Runoff is then directed to a cast-in-place concrete cistern constructed in the parking garage. High permanent groundwater required a highly reinforced ballasted concrete structure to resist hydrostatic pressure and to provide a factor of safety against buoyant forces. Contaminated groundwater at the storage cistern could not be remediated and therefore the cistern and the CDS required extensive external chemical resistant waterproofing to prevent pollutant migration to the interior of the storage cistern.
To store the required ESD WQ Volume the cistern was constructed with an emergency “spillway” to tidal waters and an isolation shear gate to close for maintenance. Integrated into this structure was a series of treatment chambers for secondary and tertiary treatment.
The first treatment chamber is for flow stilling, followed by a second chamber that contains a VortClarex® oil/water separator and oil containment baffle. The VortClarex uses coalescing media to efficiently remove freely dispersed oil and other liquid pollutants from runoff.
The third chamber houses a bank of Stormwater Management StormFilters® used to polish the effluent to be pumped to the Casino. StormFilters are rechargeable, self-cleaning, media-filled cartridges to absorb and retain the most challenging pollutants from stormwater runoff including total suspended solids, hydrocarbons, nutrients, metals, and other common pollutants.
The fourth partition houses a Variable Frequency Drive (VFD) pump to meet the variable flow and pressure requirements of the irrigation and sanitary demands of the Casino.
A final treatment stage with computerized variable demand control systems provided by Contech is housed in the Casino’s mechanical room. This treatment system provides for ultraviolet disinfection, micron filtration, auto switching between non-potable and potable water sources, trace dyeing of the non-potable sanitary use water and auto switching for the irrigation use of the system. The system pumps 200gpm at 116psi.
The casino opened in 2014. During the first two weeks of operation, the casino used approximately one million gallons of potable Baltimore City supplied water. During the same period, the casino used 250,000 gallons of harvested rainwater for sanitary greywater use and irrigation.
The casino has received LEED Gold certification from the U.S. Green Building Council.