Micron Pond Odor Issue

For those with questions about the pond behind the Sandy Court cul-de-sac, please see the below information that may be helpful to you.

Update - Saturday, July 5, 2014
We have made significant progress in draining the pond, however, it has also brought about a new challenge. The pond is currently below 3.5 feet in depth, which on one hand is almost empty, but on the other hand means that the bottom of the pond is becoming exposed. The bottom of the pond is where significant biological activity occurs and the hydrogen sulfide is formed. As this area becomes exposed the odor is easily released directly into the atmosphere and travels with the prevailing breeze.Over the past several weeks, staff have been managing odor when draining the pond, but unfortunately those have no effect on odor emanating directly from the pond surface area.

In an effort to accelerate our progress we will continue our draining efforts through this weekend. We expect the pond to be empty by midweek, which will be followed quickly with efforts to scrape and clean the bottom of the pond.On Friday, June 6 at 7:30 p.m. a meeting was held with the residents of Sandy Court and the surrounding area. In attendance were Mike Moon, City of Manassas Director of Public Works and Utilities; Tony Dawood, City of Manassas Deputy Director of Water & Sewer; Brian Balchunas, HDR; Chris Dott, Director of Operations & Maintenance for Micron; Hal Parrish, City of Manassas Mayor and William Patrick Pate, City Manager. Below is a summary of the meeting:

An overview of the City’s procedures developed in June, 2012 for managing the Micron industrial wastewater storage pond was given. Under the 2012 plan a Bioxide treatment system was installed to control odors that, under certain conditions, can emanate from the pond. It was also determined that the normal flow condition for the pond would be empty “in bypass” and only used in wet weather to help the City manage their wastewater flows by diverting Micron’s pretreated effluent into the pond.

The City’s current maximum allocation for wastewater capacity is 8.689 mgd (million gallons per day); our current 48 month – 30 day rolling average is 8.22 mgd, which translates to 94% of the City’s total capacity. It was noted that the pond covers 16 acres and can hold up to 100 million gallons. The pond is operated under an Industrial Wastewater Discharge Permit issued by the Upper Occoquan Sewage Authority in September, 2000.

Some history:
Prior to this current situation, the last complaints regarding odors emanating from the pond were received in 2012. The wet weather and heavy snow events in the winter of 2013/2014 required the use of the pond for storage. The City began diverting industrial wastewater into the pond on Jan. 6, 2014 and could not begin draining it until May, 2014.

Once draining of the pond was initiated and odors started to occur, Bioxide treatments, in addition to the standard maintenance dosage, were applied to the entire pond, but the odors coming from the pond did not appear to be significant. At that time it was believed that the City trunk line that runs along Winter’s Branch was a secondary issue; however, as a result of our recent investigation it was determined that the City underestimated the odors emanating directly from the pipeline. Staff apologized to the citizens that have experienced odors in their homes.

Short and long-term actions:
On a short term basis the City has reduced the outflow from Micron Pond and has installed temporary monitors at several locations in the cul-de-sacs to monitor the level of hydrogen sulfide in the distribution system. The City has not observed any levels of hydrogen sulfide in the cul-de-sac areas that would pose health issues. The City estimated it would take approximately 30 days to drain the pond. The City will regulate the discharge to minimize odors in the system and will only discharge at times when the residential sanitary usage is at a minimum.

On a long-term basis, the City has identified capacity issues in the trunk line that will be studied to determine the best course of action.

Brian Balchunas from HDR, an expert on hydrogen sulfide, provided an overview of the impacts of hydrogen sulfide and the issues associated with the chemical.

Follow-up actions by the City:
  • The City will establish an email/contact list of residents who wish to have more information and communicate regarding actions being taken.
  • Darren Branch, Assistant Water & Sewer Director, will send out a copy of all of the questions asked at the meeting.
  • The City agreed to two (2) follow-up meetings with residents:

  1. A meeting with the Virginia Department of Health
  2. Follow-up meeting on long term actions – to take place by the end of July 2014

If you have any questions or would like additional information, please contact the Water & Sewer Department between the hours of 7:00 am to 3:30 pm at (703) 257-8380. To report any issues after normal business hours, please contact our 24-Hour Operations Center at (703) 257-8353.