4. a-c Staff Report-sewer operations and maintenance
Staff Report
Date of Meeting:
To: City Council
From: Neil Soltis, Administrator
Re: Sewer system operations and maintenance
The following is an update on the operations and maintenance activities for the 3 sanitary sewer
systems:
Ongoing monitoring: The inspection and sampling forms have been modified to create a separate
monthly report for each system in order to ensure that the required sampling and testing is
conducted and properly documented. All reports have been submitted to the MPCA on a timely
basis.
Pump Maintenance: General Repair performed inspections of and any needed maintenance on the
8 lift pumps at the Bliss addition, 2 at Anderson-Erickson, and 1 at the Uptown system. Drawdown
tests to calibrate the lift station pumped were performed earlier in the year; however, portions of
the data needed for the calculation were not collected. The data collection forms have been
revised based on the MPCA calculations and the drawdown tests will be conducted again late this
month.
Septage tank inspection and disposal:
In the Bliss addition 68 septic tanks were inspected to determine the sludge and scum
levels. As a result of the inspections new locks were needed on 4 panels, a panel that was
not operational was replaced, 1 panel was identified for repairs, 6 locations were identified
were the covers needed to be raised. 14 tanks were identified to be pumped; however, the
septage must be land spread or disposed of at a MPCA facility that has been licensed to the
City and the City needs to have a licensed Level 4 operator. No one on the City staff has
that designation and the City has not gone through the process to have a site licensed for
land spreading. Conversation have been initiated with the City of Marine regarding using
their licensed facility under the direction of their operator. The process requires a public
hearing with a 30 day notice.
In the Anderson-Erickson addition 25 septic tanks were inspected. As a result of the
inspections a new lock was placed on 1 panel and 7 tanks are scheduled to be pumped this
month.
The tank that serves the Uptown system is scheduled to be pumped this month.
Inflow & Infiltration:
The Bliss system is designed to treat up to 19,800 gallon per day. Normal flow ranges from
6,000 to 10,000 gallons. During rain event in September flows into lift station #3 increased
to 31,461 gallons on 9/21 and 24,834 gallon on 9/30. This indicates that there is a
significant amount of inflow and infiltration into the system. The increased flow from lift
station #1 was not significant with the greatest increase in #2. Raising the height of the
risers likely had an impact and completion of that work may help to reduce the I&I;
however, at some point additional work will need to be conducted to identify the sources.
The flow increases at Anderson-Erickson, where the design capacity is 6,700 gallons per day)
increased from 2,000 – 3,500 gallons per day to over 6,900 gallons and the Uptown flows
increased from 800 – 1,200 gallons per day to over 2,000 gallons.
From Ryan Goodman
My thoughts on the increased pumping during the heavier rain events in September are
directly related to I/I or pumping twice.
I/I (Inflow and Infiltration)
• Sump Pumps could directly be discharging into the system. City could complete a
sump pump inspection program.
• Manhole Lids/Barrel Joints – Check all manholes are water tight and/or elevation of
rim is above drainage flow during heavy events and barrel joints aren’t seeping in
groundwater.
• Cracked/Broken Joints Gravity Pipe – Complete Televising.
• Service Line – Line between house and tanks could have a lot of I/I (Marine on St
Croix has this issue)
Pumping Twice
• Does the system have a backflow preventer that is not properly work? This was an
issue on the Anderson/Erickson system early in the investigation of the system.