BT Sanitary Sewer Infiltration 2016

High Sewage Flow 2016


Each month the Township’s sewer system operator (Infrastructure Alternatives) provides the Township with a monthly report on the operation of the wastewater treatment plant (WWTP) and the collection system. Upon receipt of the February 2016 report it was determined that the incoming flow to the wastewater treatment plant experienced a significant spike (see attachment A). The system operator informed the Township that a similar spike had occurred in December 2011 (see attachment B). The source of the December 2011 increase in flow was not located and flows returned to normal levels by June of 2012.

​In light of the fact that the current increased flow was not adversely affecting the WWTP operations and the system remained in full compliance with the Michigan DEQ operation permit, the operator was afforded the opportunity to recalibrate inflow measurement equipment, take pump station readings to possibly identify the area within the Township where the increased flow was originating and to monitor the flow into the plant to determine if the spike would mirror the December 2011 occurrence.

​Following the collection of the additional data, and in light of no reduction in the spike through the first quarter of 2016, the Township met with our system operator and Township engineer (OHM), to review the flow data and implement a focused search for the source of the additional flow. This is no small task as the system consists of approximately 29 miles of sanitary sewer at depths of up to 30 feet below the surface.

​On May 27th, following extensive field investigations, our engineers located a source of significant ground water infiltration within one of the manholes. The Township Engineer has provided the attached video (see attachment C and attachment D). The first step of repairing this manhole was performed on June 8th and 9th (see attachment F). The contractor will be returning approximately 2 weeks later to assess the repair and make any additional corrections.  Staff will be monitoring the flow that is entering into the WWTP to determine if this leak is the root cause of the increased flow or whether other sources of infiltration must be located.

​On a side note, The Township engineer was asked to measure the flow entering the system through the manhole and analyze the wastewater characteristics that the WWTP was processing in December 2015 compared to January – April 2016. OHM has provided that report (see attachment E). In light of the results, OHM was asked to confirm their composition analysis by looking at a larger sample for the additional periods prior to December 2015. Brighton Township is awaiting that updated report. 

Update June 17th: The sewage flowing into the Waste Water Treatment Plant continues to be monitored following the repair to manhole #300A.  The daily flow report through 6/16/16 is listed as attachment G.  The repair reduced the inflow to a limited degree. Televising additional infrastructure is scheduled for the week of 6/20/16 toward the identification of other points of infiltration.

Update June 21st:
The Township received the following letter (attachment H) from the DEQ as follow-up to a complaint that a resident had filed with their office.  In summary, the DEQ investigated the matter, found no compliance issues regarding the operation of the sewer system and closed the complaint.

Update June 23rd:
The Township engineering consultant provided an expanded and updated analysis regarding wastewater characteristics.  This report updates the June 1, 2016 OHM memo which was based upon a limited window of monthly operating data. (attachment I).

Update June 28th:

The Township Sewer System operator, IAI, located a second source of infiltration within manhole #300A.  IAI restricted the flow of sewage from flowing into manhole 300A and confirmed a gap on the underside of the inflowing pipe.  The infiltration of clean ground water into manhole #300A was confirmed. Steps are being taken to coordinate the repair.
 
Update July 15th:
Contractors were on site making repairs within manhole #300A on July 13th and 14th.  Video of the manhole following repair can be seen as attachment J and attachment K.

Update July 25, 2016:
On July 19th, IAI noticed an increase in the flow coming into the WWTP.  An inspection of the previously repaired manhole #300A indicated the repair was intact.  However, an inspection of the adjacent manhole #301 revealed a new source of infiltration.  On July 23rd the Township's contractor made a partial repair of manhole #301.  Video of the before and after for work performed on July 23rd can be see at attachment L and attachment M
  
Update September 6, 2016:
Per attachment N, the monthly flow comparison reflects the flow for the month of August has returned to 2015 range.