Engineering Excellence – we have a reason to celebrate!

By Jenn Hussey  |  March 23, 2017  |  Featured News

Each year, ACEC/VT (the American Council of Engineering Companies, Vermont) has an engineering excellence competition starting in January. Engineering companies are invited to submit entries within six different categories that display engineering excellence. After the applications are submitted, the firms have about a month to create a 2′ x 3′ board and single page narrative explaining how their project exemplifies engineering excellence in five areas:

  • Meeting and Exceeding the Client/Owner’s Needs
  • New Applications of Existing Techniques/Originality/Innovation
  • Social/Economic Considerations
  • Complexity
  • Technical Value to the Profession of Engineering

These boards and narratives are then reviewed by a panel of judges who score all submissions. Merit awards are bestowed on all projects deemed worthy of the recognition in a given category. A single Grand Award can be bestowed in each project category.

For 2017, Aldrich + Elliott received two of the five Grand Awards bestowed on prjects for:

  • St. Albans Tertiary Phosphorus Removal Pilot Study
  • Hinesburg Nano Filtration Water Treatment System

The boards and awards were displayed at the Engineer’s Week banquet on February 24th and they will be on display again this June at the awards banquet.

Winning a grand award is an honor for both A+E and our clients. It is in collaboration with our clients that we are able to work on such great projects and exemplify engineering excellence. Descriptions of the two project submitted are noted below.

St. Albans WWTF Advanced Tertiary Phosphorus Removal Pilot Study

To no one’s surprise, the Lake Champlain Phosphorus Total Maximum Daily Load (TMDL) was re-issued by the EPA in 2016, and mandated stringent effluent limits for total phosphorus (TP) at wastewater treatment facilities (WWTFs) discharging into the Lake Champlain watershed. As early as November 2014, EPA indicated that WWTFs with a permitted capacity equal to or greater than 200,000 gpd, may be required to meet an average effluent TP limit as low as 0.2 mg/L. Further, the TMDL contains an Accountability Framework where – beginning in 2017 – EPA can assess implementation and success targets of all non-point source reductions. If Vermont does not meet the targets set in the TMDL, EPA reserves the right to impose effluent limits as low as 0.1 mg/L TP or “to the limits of best available technology” for the larger municipal WWTFs. At the time it wasn’t clear whether there were suitable, reliable, effective and economical technologies that could consistently meet these lower limits, so Vermont DEC and the City of St. Albans sought answers though the largest tertiary phosphorus removal pilot study every conducted in Vermont. This information would be used by Saint Albans, as well as other Vermont communities, to inform decision making related to WWTF infrastructure investments.

The primary objective of the pilot study was to determine the feasibility of meeting an effluent total phosphorus concentration of 0.1 mg/l or less in various operating conditions. Four tertiary treatment technologies were piloted: Veolia – Kruger Actiflo Ballasted Flocculation, Veoila – Kruger Hydrotech Discfilter, Aqua-Aerobic Systems – Cloth Media Filter, and Blue Water Technologies – Centra-flo Filters with Blue PRO Process.

The pilot study consisted on four testing periods: chemical and hydraulic loading optimization; steady state testing; high solids stress test; hydraulic stress test.

Based on the results of the pilot testing, only the Blue Water Technologies Centro-flo filter with Blue PRO Process consistently met the effluent total concentration objective of 0.1 mg/l TP or less. However, pilot results did show that all of the technologies tested are capable of removing phosphorus to low levels.

Using the information gathered during the pilot study, the City continues to evaluate options to meet the Lake Champlain TMDL effluent TP limit. They have a much better understanding of the costs, design requirements, and limitations of the piloted technologies specific to their facility, and can make an informed decision on how to proceed with and invest in improvements at their WWTF. The same can be said for other WWTFs throughout Vermont who can use the results of this pilot study to make informed decisions on investments in their wastewater infrastructure. They can assess whether pilot testing is warranted, and if so, which technologies to consider. This critical information did not exist prior to the completion of this study.

A link to the ACEC Grand Award winning St. Albans Pilot Study board can be foundĀ here.

Hinesburg Nano Filtration Water Treatment System

In 2012, Vermont DEC notified Hinesburg that they must develop a new water supply to replace two existing wells with diminishing yields and MTBE contamination. Two new water supply wells were constructed off Shelburne Falls Road, which would provide adequate yield to replace the existing wells, but water quality testing indicated that they well water had “very high” hardness (330 mg/L). Acceptable hardness levels are generally in the 75-125 mg/L range. There are no known health risks associated with consumption of hard water, however there are nuisance problems such as: gray staining of washed cloths, reduced lathering of soaps, buildup of scale on heating elements, and reduced water flow in hot water piping – due to scale buildup.

The town considered whether to treat the water at the source or burden each consumer with dealing with hardness themselves. Some consumers already had water softeners, but many did not. Through public forums, the matter was debated and the Selectboard decided that treating to water at the source was the “right thing to do”. While the townspeople were pleased by the decision, they were concerned about how to treat the water. Conventional softener treatment removes hardness by a process known as ion exchange where water is introduced in the top of a vessel and passes through ion exchange resin where unwanted hardness ions (calcium and magnesium) are removed. Once the resin has reached capacity, it is regenerated with salt and placed back into service. One byproduct of this process is elevated levels of sodium (salt) in the finish water – a significant concern. This is when a local solution to the problem was discovered. ISI Water Systems is a leading manufacturer of membrane filtration systems – typically used for desalination. They have furnished membrane filtration systems throughout the US and the world, but membrane filtration had never been used to treat a municipal potable water supply in Vermont.

Membrane filtration uses semi-permeable membranes to remove dissolved contaminants through reverse osmosis. In Hinesburg’s case, Nano filters are sized specifically for water softening to remove magnesium and calcium. The process is so effective that Hinesburg only filters 30% of the water and blends it with unfiltered water to achieve a consistent hardness level of 100 mg/L. Study of the two alternative treatment technologies, including life cycle cost analysis, demonstrated that Nano filtration has both a lower capital cost and operating cost. It is much more automated, thus requiring substantially less labor to operate, and did not elevate sodium levels in the finish water. The social/economic benefit is significant. Membrane filtration has been proven to be cost-effective, and well suited to address hardness issues in drinking water systems – without elevating levels of sodium in the finish water.

Hinesburg continues to seek new water sources to meet future demand. Should new water sources be found near the current ones and have similar hardness issues, adequate space and other provisions were designed into the Water Treatment Facility to house another Nano filter and associated equipment. Vermont water systems and engineers now have a new proven technology for removal of a variety of water contaminants.

A link to the ACEC Grand Award winning Hinesburg Nano Filtration Water Treatment System board can be found here.

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