BILCO doors protect pumps, help Virginia community solve water issues
The Hampton Roads region in eastern Virginia, United States, faces challenging issues with water quality and land subsidence, but a new project is helping to provide a sustainable source of groundwater.
A central part of the system is specialty access doors manufactured by The BILCO Company of Connecticut. The doors protect pumps and vaults in the complex system, and play a vital role in protecting water and other matter from infiltrating the system.
The innovative water treatment program called Sustainable Water Initiative for Tomorrow (SWIFT) is managed by the Hampton Roads Sanitation District (HRSD). The project takes highly treated water and puts it through additional rounds of treatment to match drinking water quality standards.
Just as important, the SWIFT water will be added to the Potomac Aquifer, which will slow and even reverse the shrinking of land due to withdrawal. Land subsidence—the gradual caving in or sinking of an area of land—has been observed in the Chesapeake Bay region at rates of 1.1 to 4.8 mm (43 to 189 mils) per year since the 1940s, according to a U.S. government report.
Increased water usage in the region is a direct result of a surge in population. The Hampton Roads region population swelled from slightly under 600,000 residents in 1960 to more than 1.7 million in 2016, according to estimates. In Virginia Beach alone, the population increased from around 8000 in 1960 to more than 450,000 in 2016.
“This is a great project, because 90 per cent of what we currently discharge will no longer go into the Chesapeake Bay,’’ says Ted Henifin, general manager of HRSD. “It will be treated, purified, and put into the ground where it can provide other benefits.”
The $25 million research centre, located on the grounds of Nansemond Treatment Plant in Suffolk, is capable of producing 4 million L (1 million gal) of SWIFT water per day.
The system revolves around an eight-step process that completes three primary objectives. The process includes flocculation and sedimentation, ozone contact, biologically active filtration, granular activated carbon contractors, ultraviolet (UV) disinfection, chlorine contact, chemical addition, and aquifer recharge.
When wastewater enters an HRSD treatment plant, it first flows through a bar screen that removes large floating objects such as trash, sticks, and rags. The captured material is properly disposed of in a landfill and the wastewater flows to a grit chamber and a sedimentation tank. These devices slow the flow of the water and allow sand, grit, human waste solids and other small particles to settle to the bottom. These solids are then removed along with any scum or grease floating on top.
The wastewater then travels to secondary treatment facilities that speed up the processes of nature, allowing microorganisms (bacteria and other organisms) to consume 80 to 90 per cent of the ‘organic matter,’ or human, animal, and plant waste.
The wastewater is then sent to a final clarifier, and advanced treatment systems remove additional pollutants such as nutrients, heavy metals, and chemical compounds. The final step includes disinfectant with chlorine and UV light. HRSD facilities remove excess chlorine before discharging the cleaned water into local rivers. These processes kill 99 per cent of disease-causing pathogens such as bacteria and viruses and allow the water to support the intended use of the area waterway and can be released back into the environment.
Two underground pump stations and a number of vaults are key parts of the process. The vaults and pumps are protected by channel frame doors that prevent water and other liquids from entering the access opening.
The doors are manufactured by The BILCO Company of Connecticut. There are seven doors protecting the valves and pumps in the sophisticated system, along with three LadderUP® Safety Posts, also manufactured by BILCO. The posts provide easier, safer access through floor doors, roof vents, and manholes.
Two BILCO roof hatches were also used in the project. Marcor Associates of Midlothian, Va., delivered the doors, hatches, and safety posts. Crowder Construction and Hazen and Sawyer served as general contractors (GCs) on the project.
The doors feature a channel frame design to prevent water and other liquids from entering the access openings and engineered lift assistance for easy, one-hand operation. The corrosion-resistant aluminum doors were also supplied with Type 316 stainless steel hardware to stand up to this harsh water processing environment.
Other areas of United States are facing similar issues with wastewater and land subsidence, and the SWIFT project could offer a template that might be usable for other communities.
“SWIFT requires some geological features to be fully successful that are location specific—a confined thirsty aquifer being the primary requirement,’’ Henifin says. “But largescale success with a carbon based process—eliminating the need to deal with a waste brine stream—opens the possibility of recycling wastewater throughout the country.”
All information listed in this section was submitted by The BILCO Company.
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