water

At the Water Authority of Western Nassau County’s (WAWNC) Plants 28 and 30, 7.0 MGD of potable drinking water is supplied to consumers through a series of four groundwater wells. Iron concentrations at both plants had exceeded the established standard and rendered the existing treatment ineffective. The presence of iron in the groundwater had also severely impacted the well itself, leading to a considerable reduction in capacity. WAWNC made the decision to install an iron treatment system to remove the iron from the groundwater—making sure to keep in mind that the site in question was located in the middle of a residential neighborhood. Sand filtration technology is a proven, cost-effective approach for the removal of iron from drinking water. WAWNC elected to install a pressurized sand filtration system that would be fully automated, which simplifies operations and requires only routine maintenance from plant personnel. To situate this plant in the residential neighborhood, all aspects of the plant, including filters, the control room, chemical storage, piping and equipment, were designed to blend in, utilizing features consistent with surrounding properties. Sustainable design elements such as LED lighting and cementitious siding were included to lessen the project’s impact on the environment. Since inception, the result has been iron-free water, reducing rusty water complaints and ensuring a clean, reliable source of drinking water to WAWNC’s customers for years to come. The completed design met and exceeded the client’s desire for a sustainable-oriented facility that blends in with the existing neighborhood. The automated controls of the facility will continue to add to the cost efficiency of this plant.

South Farmingdale Water District was ready for an upgrade to its iron removal system. The existing system had been designed and constructed in 1998 and used a Ferrosand for filtering. Experiencing reduced back wash run times and iron clogging, the District chose H2M for the upgrade of the filter media. H2M specified a manganese greensand for the new filter media. Greensand is an organic clay mineral product that is bluish-green in color. As water is passed through the greensand material, soluble iron is oxidized from the solution and becomes a solid particle. The solid iron oxide is then trapped in the greensand filter. Updating the filter media to this material allowed the District to switch from using potassium permanganate for regeneration of the greensand to using only chlorine; chlorine being both cheaper and easier to use and store than potassium permanganate. A second benefit was the durability of the greensand, which allowed for less frequent backwashes and a lower percentage of waste. Reusing the two 8-foot diameter, 23-foot long horizontal pressure vessels for the iron removal system, the upgrade included updated controls and chemical treatment safety panels. The project met its goals for both time and budget.

Routine inspection of the South Huntington Water District’s Plant 13 concrete tank revealed deficiencies that needed to be addressed. The concrete dome roof was in poor condition. Patch repairs weren’t holding. Something was going to give. The District hired H2M to design a replacement for the 50-year-old, post-tensioned concrete dome roof. An aluminum geodesic dome design was selected for its lightweight, low-maintenance construction and ease of installation; with an aluminum frame and panels, corrosion would not pose an issue, and no painting or coating system would be required. New OSHA-compliant interior and exterior access ladders, complete with a stainless steel cable safety climb system, were also installed. The District took this opportunity to coat the exterior of the tank. The existing coating had become unsightly and unflattering for the highest visible point in the Town. Selecting a modern, high-performance coating system compliant with all New York State Department of Health VOC emission regulations, H2M specified a breathable, waterborne, single-component, acrylic elastomeric coating. The roll-on and spray-on coating system was easy to apply to the tank’s exterior after cleaning. Providing design services, construction administration, and inspection, H2M brought the project in both on time and under budget, a win-win for everyone.

Plainview Water District’s 1.25 million-gallon elevated water tank, constructed in 1970, was in need of a full interior and exterior coatings rehabilitation. Inspection of the carbon steel tank revealed that its existing coatings system had reached the end of its expected service life and was exhibiting blistering, delamination, and corrosion across 60 percent of the structure. Rehabilitation of the carbon steel tank required abrasive blasting, a process that generates an enormous amount of dust. With the tank located in the middle of a residential neighborhood, it was critical that a fully engineered containment system alleviate dust nuisance. H2M specified a containment system that resulted in not a single dust complaint from the surrounding neighborhood over the six-month term of the project.

The Hagerman Fire District in East Patchogue was looking for a way for their fire response personnel to use the location of hydrants, major points of interest, and roads in order to enable route finding and reduce response times. Utilizing Geographic Information System (GIS) mapping software, H2M created a new District map identifying these items as well as a street index for easily locating streets. The map combined GIS data layers from county agencies with custom GIS layers created by H2M in order to provide an up-to-date representation of conditions throughout the District. For easy reference, we also provided the District with a set of wall-sized maps, as well as smaller maps for on-the-go use in their emergency response vehicles. The use of GIS allows the map to be quickly and easily updated and configured in the future.

Like many municipalities, the Town of Clarkstown was starting to face a number of challenges due to aging infrastructure: sewer overflows due to failing equipment and a lack of emergency power generation; stormwater inflow from surface runoff; and groundwater infiltration through cracked pipes and leaking joints. With financial assistance from the Rockland County Sewer District, the Town of Clarkstown established a capital improvements program to replace outdated technology and bring the Town’s pump stations into compliance with the most current Ten States Standards. Reducing stormwater inflow and infiltration in gravity sewers reduces the demand on pump stations and receiving sewage treatment facilities. H2M is currently upgrading nine of Clarkstown’s sanitary sewage pump stations to include new pumps and controls, valves, and force main piping to connect to existing force mains. We are utilizing precast structures such as wet wells, valve vaults, and control buildings to minimize on-site construction, and we’ve selected architectural finishes, fences, and landscaping to incorporate the pump stations into the local residential neighborhoods. Emergency standby generators will be supplied to all nine pump stations to ensure that equipment will continue to operate in the event of a power outage

Looking for a rehabilitation of one of their three water tanks, the City of Yonkers called H2M. After performing a structural and coating systems evaluation on the 1 million gallon steel elevated storage tank, H2M recommended full rehabilitation of the interior and exterior coatings. The existing systems were chipping, peeling and chalking, signs that they had reached the end of their expected service life. H2M also recommended installation of a passive Tideflex mixing system, which would allow the Water Department to easily turn over the tank’s contents and mitigate stagnant water inside the tank. Construction was timed to start in the fall, after the City’s pumping season ended. Early winter weather caused a delay that put the project at risk of missing the next pumping season. Reworking the schedule, H2M directed the interior coating and the Tideflex installation during the winter months, and the exterior prep and paint work in the spring. The schedule was met and the project completed on time. H2M provided the traditional services of contract administration and construction inspection as well as a newer, but much needed service, cellular coordination. As water towers are often the tallest structures in the area and cell phone networks continue to fill in their missing service areas, the two have come together, with cell phone antennas mounted to the exterior of the water tank. For the City of Yonkers, their 202 foot tall tank was home to 18 antennas from multiple wireless phone companies. H2M coordinated the removal and re-installation of antennas, routing of conduits, and upgrade of equipment during the rehabilitation.

Long Island American Water (LIAW) was concerned about the condition of two of its water mains; crossing the Reynolds Channel, both mains serve as transmission mains to supply water to the Village of Atlantic Beach, a barrier beach community located on the south shore of Long Island. After conducting visual inspections and leak detection surveys of the two transmission mains, LIAW determined that the west crossing was partially undermined and exposed at the bottom of the channel. A considerable leak was also discovered in this same main. The east crossing was found to be in satisfactory condition. LIAW elected to plan for the replacement of both crossings, with priority given to the west crossing because of its poor condition. Ultimately, the west crossing was completed in September 2011, while the east crossing is slated for replacement within three to 10 years. H2M prepared design documents for the replacement of approximately 1,400 LF of existing 16” water main at the west crossing and approximately 2,200 LF of existing water main at the east crossing. The replacement consists of new 20” diameter, corrosion-resistant High Density Polyethylene (HDPE) pipe, installed via horizontal directional drilling (HDD). This trenchless excavation method eliminates the need to dig elaborate trenches in order to replace piping, reducing construction costs and minimizing the project’s impact on the surrounding area.

The Hicksville Water District faced a difficult task when high levels of nitrates and volatile organic compounds (VOCs) were found in two of their water supply wells. The source of the contamination was determined to be former residential septic systems that were still in place, over-fertilization of lawns and farms, and industrial operations in the area. H2M was tasked with finding the most viable and cost effective treatment solution to correct the nitrate and VOC problem. The nitrate issue was addressed with the addition of an ion exchange system. The idea behind an ion exchange system is to run a water stream through a pressurized vessel containing ion-exchange resin. The resin consists of small beads (0.5 to 1 mm in diameter) made from an organic material. The beads appear solid, but allow for microscopic particles to pass in and out of their skins, much like living cells transfer solutions through their cell walls. In this case, the ion exchanger removes nitrates from the water stream, which is then blended back into the pumped well water. Removal of VOCs was handled using an air stripping system. Using a tower for this process, the contaminated water is sprayed into the top of the tower and allowed to filter down through a plastic packing medium which increases the surface area of the water. At the same time, air is forced into the base of the tower and exhausted out the top. As the air and water droplets collide, VOCs attach to the air molecules and are “stripped” out of the water stream. The cleaner water then exits the tower base and is returned to the water supply. H2M’s completed design included a new building to house the ion exchange process, a new air stripping tower, pump modifications and a new process control system. With a flow rate of 3.4 MGD, the new water treatment processes reduce nitrates and VOCs to well below maximum contaminant levels (MCL) for both compounds.

When the South Farmingdale Water District sought to enhance their existing water supply and distribution system management program, they turned to H2M to create a GIS to meet their needs. And when they decided that they would need on-the-go access to their data, they requested a mobile GIS solution. The District’s new ArcGIS-based map contains over 40 layers, including road right-of-ways, street names, water mains, valves, fire hydrants, tax parcels, water plant sites, buildings, boundary lines, and land surface contours. Over 1,000 valve sketches were scanned and hyperlinked to the valve layer, providing the District with quick access to vital information in an emergency situation, such as a water main break. Updates to the GIS are able to be made as the distribution system changes and newer data becomes available. H2M also developed a new mobile GIS system using tablet computers for the District. Setting up a secure ArcGIS.com cloud-based web map, the maps can be viewed on Apple iPads and other tablet computers. The free ArcGIS mobile app provides the same capabilities of their existing desktop GIS, such as the ability to identify features’ attributes, switch basemaps, measure lengths and areas, and access valve sketches and record maps quickly and effortlessly in the office and out in the field. The iPads also provide the ability to collect additional GIS data and photos, leveraging the tablet’s internal GPS to zoom directly to a specific location.

The Greenlawn Water District owns and maintains the tallest water storage tank on Long Island. At 219 feet above grade, the tank holds 1 million gallons of water to help support water pressures to Greenlawn’s 12,000 customers. H2M performed preliminary inspection, prepared plans and specifications for the rehabilitation of the tank and provided inspection services during the rehab. Beginning with a Present Condition Evaluation (PCE), H2M conducted a comprehensive, on-site evaluation of the structure’s current condition. Certain design elements required specialized treatment, such as containment during abrasive blasting operations, considerations for the height of the structure and VOC limitations for potable water interior coating systems in New York State. Upon completion of the project on schedule and within budget, Robert Santoriello, Superintendent of the Greenlawn Water District said, “This is a prime example of a well-organized firm, keeping us informed throughout the project. H2M has an intimate involvement with the project to ensure success when the final product is completed.”

Located within New Jersey’s Passaic County, the Borough of Ringwood’s water utility needed upgrades to its outlying area—the Upper Ringwood Service Area. H2M was retained to provide reliable, quality water supply without excessive levels of unaccounted water loss. Long-term solutions for reliable water service were found by identifying the most critical water infrastructure features in need of resolutions. Prior to the project, pressure regulation and disinfectant application was labor-intensive, requiring water treatment operators to visit the chemical feed system, which was located in a confined space, twice daily, every day to adjust dosage. Another issue due to the manual operation of the tank, was its frequent overfilling, wasting nearly 1 million gallons of water per week. H2M incorporated a SCADA system into a Chemical Safety Panel to improve operations and system performance. Upon system startup, the SCADA flow control immediately stopped the tank from overtopping when excess water was introduced into the system. A large leak in the system was also discovered by the system, which led to recovering 100,000 gallons of unaccounted water per day. Solar panels were also designed to provide power to the instruments and radios. The project demonstrates that even small systems can deploy SCADA technology effectively, and at reasonable cost. Overall, the project saves the client approximately $106,000 per year in wasted water, leading to capital recovery in less than five years.

With Wells 7-1 and 7-2 impacted by contamination, H2M was retained by the South Huntington Water District (SHWD) to evaluate and determine the most viable and cost-effective VOC-removal treatment technology. H2M prepared an engineering study for SHWD to evaluate available VOC removal alternatives, which concluded that granular-activated carbon (GAC) pressure filters would be the best treatment solution for the client. H2M later went on to design and prepare construction documents for a new GAC treatment facility and would be able to treat a total of 4.0 MGD through four carbon pressure filters. The scope of the project included rehabilitation of two 2.0 MGD ground water wells, modifications to existing site piping, and the demolition of the existing pump houses. A 2,780-square-foot masonry building was constructed to house Well 7-2, four 12-foot diameter GAC pressure filters, a 4,000 gallon horizontal caustic storage tank, calcium hypochlorite tablet chlorinators and chemical metering pumps for pH adjustment and disinfection. A 245-square-foot masonry building was built on site to house Well 7-1. There is also a 500 kW standby generator to feed power to both wells in the event of a power outage.