Stormwater Management Archives

Capital Improvements and Asset Management Plan, Gardner, MA

Tata & Howard prepared a Capital Improvements and Asset Management Plan (CIP) for the existing water, wastewater, and stormwater systems. The purpose of the CIP is to develop a complete inventory of all assets with replacement costs and useful life to assist the DPW in identifying areas in need of rehabilitation, repair, or replacement and prioritize improvements to make the most efficient use of the DPW’s budget.

The CIP was divided into three parts, water, wastewater, and stormwater systems. Buried and above ground infrastructure was evaluated for the water and wastewater systems and the stormwater evaluation included drainage pipes and structures. The stormwater asset evaluation including a field inspection of every outfall. The outfalls were mapped and a condition assessment performed. Water and wastewater above ground infrastructure included all supply, treatment, pumping, and storage components. Equipment, including vehicles, lawn mowers, and construction equipment was not included in the inventory.

As part of the water and wastewater pipe asset management evaluation, each segment of pipe was evaluated based on material, age, diameter, soil conditions, break history, and system specific concerns such as static pressure, potential water hammer, infiltration and inflow (I/I) concerns, and known operation and maintenance issues. The stormwater outfalls were evaluated based on condition, catchment size, pipe size and material, size compromised and soil conditions.

The asset management plan for above ground infrastructure included an inventory and evaluation of all above ground facilities, including the water supplies, water and wastewater treatment facilities, pump stations, and storage tanks. The evaluation was used to develop a prioritized list of assets and a replacement schedule. The DPW now has a working database that can be updated as new information becomes available and can be reviewed when reviewing selection of yearly capital projects. Also, by reviewing the water, wastewater, and stormwater system together, the study can be used to make more efficient use of funds by potentially addressing water, wastewater and stormwater needs together on a street.

Funding Assistance for WWTF Upgrade in Lyndon, VT

Upgrade for a 750,000 gallon per day extended aeration wastewater treatment facility to an A/O biological facility. Assistance included acquiring State CWSRF planning grants and USDA Rural Development grant for extensive improvements including separation of combined sewer/stormwater collection systems (CSO), advanced Class A sludge treatment, and reconstruction of original 1970’s treatment facility to new Anoxic/Oxic Treatment System. Total grant funds were $7,275,000.

Stormwater Management, Whitinsville, MA

The Whitin Wellfield Water Treatment Facility design consisted of a pressure filtration vessel housed within a new pre-fabricated metal building, and upgrades to the chemical feed system housed within an existing building on site. The project also included associated electrical and instrumentation, as well as site stormwater management.

The design called for replacement of the existing paved driveway, but since no new impervious pavement was added, the only stormwater runoff that required treatment was the rooftop runoff from the new building. MassDEP guidelines require treatment of runoff from metal roofed buildings within the Zone II radius of a wellfield.

The necessary treatment was achieved by discharging the roof runoff into a grass-lined channel. The grass-lined channel provided pre-treatment for a bioretention area, which consisted of a shallow excavation in which specially selected metal-resistant grasses and shrubs were planted within a specific soil to provide treatment. This treatment train provided the necessary total suspended solids removal but did not receive credit for infiltration, which was required by MassDEP. The biofiltration area was designed to collect, store, and infiltrate a 100-year storm event, so although the BMP train did not receive credit by MassDEP standards, the local Conservation Commission agreed that runoff would be infiltrated and therefore approved the design.

Water Storage Tank Replacement, Hamden, CT

Tata & Howard provided evaluation, design, construction administration, and resident observation services to the South Central Connecticut Regional Water Authority (SCCRWA) for the replacement of the Whitney-Wintergreen water storage tank. The project included an analysis of SCCRWA’s Whitney-Wintergreen service area to determine the appropriate volume of storage needed to serve its customers, and a 1 million gallon concrete tank was constructed to replace the existing 1.5 million gallon steel tank at the same site. The project also included demolition of the existing tank as well as stormwater management at the site. The project was completed in September of 2015.

Site Stormwater Management, Falmouth, MA

Long Pond Water Treatment Plant, Falmouth, MA

The Long Pond Water Treatment Plant project consists of an 8.4 mgd DAF treatment plant, ozone contractors, and raw water pump station with intakes. The site stormwater management part of the project was separated into two designs: the parts of the site under the Conservation Commission’s jurisdiction and those that are not.

The majority of the site from the entrance along the access road and around the main treatment plant building did not fall under the Conservation Commission’s jurisdiction, and therefore did not require stormwater treatment. However, we did not want to ignore the potential impacts of stormwater, so this portion of the site was designed to allow for 100 percent infiltration. Along the access road, grading allowed for water to discharge and infiltrate in undeveloped areas where it will not impact the site. The area around the main building flows over land to an infiltration basin that is designed to collect, store, and infiltrate most storm events. There is an overflow in the case that the infiltration basin is overwhelmed during a large storm event.

The construction of the raw water pump station and intakes fell within the Conservation Commission’s and other agencies’ jurisdiction. Since the only impervious area was the building, and the building did not have a metal roof, MassDEP guidelines allowed for direct infiltration. The guidelines usually require the infiltration to occur in drywells in this situation, but the local Conservation Commission agreed that having an infiltration basin with an overflow would require fewer man-made structures and therefore have less impact on the surrounding environment. The infiltration was designed to store and infiltrate the raw water pump station roof runoff, and included an overflow for large storms.

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Site Stormwater Management, Wayland, MA

The Happy Hollow Chemical Feed Station design consisted of a small chemical feed building and equipment, well pump and water main installation, and associated utilities and site work. The only impervious surface on the site was the new building. Since building roof was a membrane and not metal and there was no paving, MassDEP guidelines allowed for direct infiltration of the stormwater runoff from the roof. This was accomplished by pitching the roof to one side and collecting the runoff into two 4” PVC drain pipes that discharged into an infiltration system consisting of four Cultec infiltration chambers.

Since it was not feasible to install an overflow for these chambers, the infiltration system was designed based on a 100-year storm event in order to have the capacity to collect, store, and infiltrate the largest storms that the site could potentially encounter. The chemical feed building also housed a re-agentless chlorine analyzer that required a constant supply of sampling water and therefore produced a constant waste flow of clean water. This analyzer waste flow was also included in the sizing of the infiltration system.

Stormwater Field Engineering, Grafton, MA

Tata & Howard has provided the Town of Grafton, MA with extensive stormwater field engineering services. Services have included the completion of stormwater infrastructure mapping in accordance with the Massachusetts NPDES MS4 Permit, Illicit Discharge Detection and Elimination Program. Mapping services included outfalls and interconnections, manholes, catch basins piping, and establishment of catchment areas. Follow-up work will continue with outfall inspection, screening, and dry weather sampling.

Stormwater Site Design Engineering, Marlborough, MA

Tata & Howard provided engineering services for Marlborough, MA for a redesign of the Town’s Public Works Facility. The work included a stormwater management design and program to reduce the contamination of stormwater runoff and prohibit illicit discharges as required by current regulations and as required by the latest draft MS4 permit.

The project also included a proposed site plan showing the proposed drainage improvements for the site including new drainage system infrastructure, stormwater detention and treatment facilities, existing and proposed grade, and all building and features. The project also included an erosion control plan and drainage report appropriate for various environmental permitting submissions including and erosion control plan with boundaries of any resource areas and associated buffers. Lastly, Tata & Howard assisted with permitting assistance and obtaining Conservation Commission approval of the project.

Stormwater Engineering Services, Leicester, MA

Tata & Howard provides ongoing stormwater engineering services to the Town of Leicester, Massachusetts in support of their status as a NPDES Phase II Municipal Separate Storm System (MS4) community. Work involves outfall mapping and inspection, Illicit Discharge Detection and Elimination, development of Annual Reports, and compliance with documentation and reporting components of the MS4 Permit.

In addition, Tata & Howard assisted the Town of Leicester Highway Department with mapping and inspection of stormwater outfalls and produced a unique record of each outfall, including photographs. Tata & Howard also developed a report summarizing the outfall inspections.

On-Call Water Engineering Services, Franklin, NH

Tata & Howard has been assisting the City of Franklin, New Hampshire with general water engineering services since 2009. The Tata & Howard team has managed several phases of work, including the design and construction of the water treatment plant and distribution system improvements.

The first phase was the design and construction of 2,500 linear feet of water main on Hill Road to connect a new water treatment plant to the City’s distribution system. This project also involved use of four bioretention systems to treat and manage stormwater from the roadway, and was constructed in 2010.

The second phase of our work with the City included the design and construction of two parallel 2,500 LF sections of 12-inch diameter HDPE crossings beneath the Pemigewasset River using horizontal directional drilling to transport water from the City’s Franklin Falls Well to the water treatment plant site.

Tata & Howard managed the survey and geophysical studies and prepared a Preliminary Design Report and Environmental Review documents for several phases of work. The City’s wells are surrounded by lands controlled by the US Army Corps of Engineers, which required that we complete an extensive permitting process to secure permissions for the final design of the project.

Tata & Howard completed design, construction, permitting, and funding applications for a 1,000 gallons per minute groundwater treatment plant to remove iron and manganese from three of the City’s wells. The plant has four pressure filters containing Greensand Plus media and using sodium hypochlorite for oxidation and sodium carbonate (soda ash) for pH adjustment. This plant went online July 9, 2012.

Tata & Howard provided design services for the construction of a new prestressed concrete tank at the site of an existing tank. The existing tank was in poor condition and due to the site characteristics, it was determined that construction of the new tank on the existing foundation of the old tank would be the best option. A second tank on the site was demolished in 2013 and a new prestressed concrete tank will be constructed in its place.

Tata & Howard also conducted a full water system analysis for the City of Franklin, New Hampshire by utilizing our proprietary Capital Efficiency Plan™ methodology. Our CEP involved creating a model of all water infrastructure in the City including sources, pump stations, treatment facilities, storage facilities, transmission, and distribution lines. Using our GIS modeling software, the system was calibrated based on fire flows in an attempt to accurately replicate the existing system. We then pinpointed deficiencies within the system based on a custom rating scale given to multiple criteria such as age, break history, material type, criticality and size. Recommendations were made for improvements in order of need. The study renewed both above ground and below ground assets. Funding for this study was in part from an Asset Management Planning Grant from NHDES.