Population flux calls for upgraded filter system in resort town
Since the early 1950s, Hungerford & Terry of Clayton, N.J., has handled water filtration for Ocean City, Md., one of the East Coast’s most popular summer resorts. The population swells from 7,000 residents in the off-season to upwards of 350,000 during the peak summer months, and this massive surge creates enormous seasonal demand for drinking water.
Hungerford & Terry continues to work with the Ocean City Water Department to remove iron and manganese from its 25 separate wells. The city’s pressure filter systems, as well as the process of pretreatment utilizing clarification with aeration plus pH adjustment, all are integral parts of this comprehensive water treatment operation.
“The treated water available today from any of the three treatment plants easily exceeds the required standards for drinking water,” said Howard Iman, superintendent of the Ocean City Water Department. “All existing plants are producing excellent quality potable water that meets all regulatory requirements.”
Upgrades and refurbishments at the three treatment facilities over the past several years have extended useful life and improved operations and reliability. Ocean City’s capital improvement plan includes infrastructure upgrades for aging and obsolete equipment. A key objective is to maintain the current high level of operational reliability with the current design treatment of 18 million gal per day (mgd) (6 mgd from the 15th Street plant, 4 mgd from the 44th Street plant and 8 mgd from the Gorman Avenue plant), in order to meet the projected 2025 maximum demand of 16.8 mgd.
Iron and manganese concentrations in Ocean City’s treated water have shown no significant increase in recent years, demonstrating that the current treatment processes are more than adequate for the foreseeable future, according to the latest report from the city.
Hungerford & Terry’s relationship with Ocean City began when Churchill Hungerford, the president and the founder’s son, was vacationing there in the early 1950s. He casually contacted the water department about any special needs it might have for water treatment, and his ideas and eventual proposal were well received. A business relationship was formed and continues to this day. Since 1953, the main objective has been to work with the city to design and maintain a clean and efficient water system that serves the greater Ocean City community all year round. Toward this end, manganese greensand filtration media from the Inversand Co. has been the filtration material of choice to produce iron- and manganese-free water for more than 50 years.
By the 1960s, the island location of Ocean City was rapidly developing from the south to the north, up to the Delaware border. As the demand for water surged with the growing summer population, it became essential to design an additional facility. The 44th Street and Gorman Avenue plants were built to handle the increase in demand through the installation of 14 pressure filters at 44th Street and 12 pressure filters at Gorman Avenue, each 9 ft in diameter.
The new wells produced water with a higher iron content. Whereas the South Well field plant contained only 2 parts per million (ppm) of iron, the newer plants at 44th Street and Gorman Avenue had upwards of 12 to 14 ppm of iron. This shortened filter runs because of the higher iron content inhibiting the filter performance. It soon became necessary to add pretreatment in order to reduce the iron load on the filters. With an updated design to assist in the pretreatment process, the iron was reduced to about 2 ppm, a level sufficient to extend filter run length and ease the load on the filtration process.
Fast-forward to the early 1980s, and still more water was required. The Gorman Avenue plant was upgraded by adding four new horizontal pressure filters, plus another clarifier for the water process.
By 1990, water department employees began to suspect that the wells on the southern end of the island were being contaminated by surface water. To correct this, the South Well field plant was removed from service, along with the 15th Street plant. A new gravity filter plant was designed and constructed while new low-head wells were installed at the 15th Street location where the old plant had existed.
Today, the Ocean City water system consists of the following:
“With a summer population that’s been expanding every year for 60 years, we have always met Ocean City’s water demand and expect to be able to meet future demands with our existing equipment or with any system expansion that may be required,” Iman said.
Time to Rebuild
For years, Ocean City’s water filters performed without any problems, shutdowns or rebeds. By 2010, however, it became apparent that a rebuild of the filter system was in order. The oldest filters had been in service since 1966 with the original filter beds. The newest filters had been in service since 1989 without a rebuild.
Hungerford & Terry proposed using GreensandPlus to replace the original manganese greensand. This was based on the superior capacity of the new media and the ability to operate at higher flux rates. In order to accomplish the refurbishing of the system, the city hired Whitman Requardt & Associates of Baltimore, Md., to prepare a specification for the work. Bids were taken and Bearing Construction of Sudlersville, Md., was successful in winning the bid.
Over the course of three months during the off-season, all 30 pressure filters were rebuilt using GreensandPlus and anthracite. Internal distributors were repaired as needed. By spring, all the filters were refurbished and ready for the intensive demands of the 2011 summer season. Ocean City is now equipped to meet the challenges of providing clean, fresh water to its ever-increasing summer population.