Recent Projects
Mashpee Water District Pilot Study
H2Olson completed a 2-week pilot scale treatability study for the Mashpee Water District which evaluated LayneOxTM media filters for the removal of source water iron and manganese. The results of the study indicated that the use of liquid sodium permanganate pre-oxidation was successful for treatment, resulting in filter effluent iron and manganese levels greater than 50% lower than the Secondary Standards.
Bench Scale Treatability Study
Bench scale treatability study that evaluated potassium permanganate for the oxidation of source water iron and manganese and alternative coagulants for the removal of natural organic matter for a challenging groundwater supply system. Optimal conditions for coagulant dose and pH were identified for simulated distribution system disinfection by-product formation testing to compare with full scale results.
Filter Media Replacement with GAC
Full scale demonstration test and design/construction of a filter media replacement project for the removal of PFAS using GAC as filter media at a 6.5 MGD surface water treatment plant in Braintree, Massachusetts. The existing mixed media filters (garnet sand, filter sand, anthracite) were replaced with 6” of 0.5 mm filter sand and 42” of 8x30 mesh GAC. The new GAC/filter sand media depths and sizes were designed to ensure a similar L/D ratio as the existing mixed media and an EBCT of 10 minutes for the GAC. PFAS was successfully removed and filtered water effluent turbidities and filter run times were on par or better than the performance of the existing mixed media filters. The addition of CO2 to the GAC media prior to placement in the filters was successfully employed to minimize the temporary increase in pH that results from fresh GAC.
Table Top RSSCT Treatability Study
Use of a table top rapid small scale column test (RSSCT) to evaluate the effectiveness and carbon usage rate of granular activated carbon (GAC) for the removal of PFAS in drinking water. The study simulated 2 years of full scale treatment of two (2) 20,000 lb GAC contactors at a design flow of 1.2 million gallons per day in 1 month.
Replacing Water Mains
Most older water systems in New England eventually exceed the useful service life of their water mains. Although this cast iron water main achieved over 100 years of reliable service, increases in needed fire flow and growth required this water main intersection to be replaced. No matter where the challenge is, congested down-town or residential, design and constructing a water main replacement project always has its challenges.
Chemical Feed Upgrade
More and more operators are finding out the benefits of peristaltic pumps, especially for the addition of sodium hypochlorite. There is no need for annoying off-gassing with a peristalic pump, and depending on the model you can dial in the feed rate precisely using the LCD screen and pump feedback. Another popular way to neaten and organize the feed piping is to purchase a pre-engineered and assembled pump skid that can also include containment. This system is one of two installed at the Guilbault Memorial Water Treatment Plant in Avon, MA.
New GAC PFAS Water Treatment Facilities
It is with great professional satisfaction that the recent GAC Treatment Facility addition for the Pecunit Water Treatment Plant in Canton, MA was approved by MassDEP in April 2024 to be placed into service! We had a great team that made this project possible, starting with the Client, the Canton Department of Public Works and their dedicated technical advisor, Peter Newton of Bristol Engineering Advisors, Inc. Work began in early 2020 with a desk-top study followed by a Rapid Small Scale Column Study (RSSCT) to identify loading rates and contact times for the removal of PFAS using GAC. Prior to this project, the existing Pecunit Water Treatment Facility used chlorination for pre-oxidation and greensand filtration for the removal of source water iron and manganese. We completed a full-scale demonstration study in 2021 using sodium permanganate for pre-oxidation instead of chlorine, since the filter effluent was going to be treated with GAC. After the successful demonstration study, the design team completed the final plans and specifications in 2022, and D&C Construction Co., Inc. was awarded a construction contract for the proposed GAC treatment facilities. Construction began in early 2023 and was completed this April 2024. Canton’s staff was a major factor in the success of this project, providing technical and operational support and assistance during all phases of the project: the RSSCT, Full-Scale Demonstration Study, Design/Permitting, Construction, and Start-Up. The contractor was excellent, finishing both on-time and on-budget. At H2Olson Engineering, we are always filled with pride for every opportunity that we get to help make safe drinking water, and being able to work alongside so many wonderful drinking water professionals!
Filter Media Replacement with GAC
Full scale demonstration test and design/construction of a filter media replacement project for the removal of PFAS using GAC as filter media at a 6.5 MGD surface water treatment plant in Braintree, Massachusetts. The existing mixed media filters (garnet sand, filter sand, anthracite) were replaced with 6” of 0.5 mm filter sand and 42” of 8x30 mesh GAC. The new GAC/filter sand media depths and sizes were designed to ensure a similar L/D ratio as the existing mixed media and an EBCT of 10 minutes for the GAC. PFAS was successfully removed and filtered water effluent turbidities and filter run