Title
Discussion: City of Hudson Sanitary Sewer Model, completed by CTI Engineers Inc.
Executive Summary: This sanitary sewer model was completed by Dave Kohlmeier and Todd Taylor of CTI Engineering, Inc. The new model included the monitoring, study and evaluation of the City's trunk sanitary sewer system, for sanitary sewers ten inches in diameter and greater, as well as other identified branches of the gravity sewer system.
Body
Legislative History
Resolution 13-144, passed November 20, 2013
Purpose & Explanation
Since 2004, the City of Hudson has completed a number of significant capital improvements and maintenance projects throughout the sanitary sewer system including sewer manhole rehabilitation, sanitary sewer lining and sewer replacement projects. As a result, an updated, comprehensive model was needed to determine the City's next course of action. The model's goal was to determine the areas of the system with the largest inflow and infiltration (I&I) and to identify methods to help in the effort to close the City's two remaining sanitary sewer overflows and potentially eliminate the Ohio EPA's consent order. In the fall of 2013, the City hired CTI Engineers Inc. to provide accurate flow metering data for dry and wet weather conditions within the sanitary sewer trunk system; create a new computer based sanitary sewer model; calibrate and analyze the data within the model. The model determined solutions to alleviate the number of sanitary sewer overflows from occurring and limit the amount of inflow and infiltration thereby reducing flows that are being treated by the Northeast Ohio Regional Sewer District.
The model identified the following:
o A total of 16 flow meter locations and corresponding drainage areas were chosen to target specific areas that may contribute high areas of inflow and infiltration.
o Of the 16 drainage areas, two (2) were identified has having relatively higher amounts of I&I. They are areas "J" (13%) and "L" (25%).
o The majority of the other drainage areas of the system indicated a level of I&I ranging from 2% - 5%.
o The model identified short-, medium-, and long-term recommendations to alleviate inflow and infiltration and reduce the amount of sanitary sewer overflows.
o Cost estimates for the proposed improvements were also developed for each of the recommendations if applicable.
Timing Considerations
The City will begin utilizing the model in the next 6 months.
Fiscal Impact
Currently Budgeted
Supplemental Appropriation Required
X Appropriation Not Required.
Recommendation
Suggested Action
· Continue an on-going City-wide inspection and rehabilitation program to reduce I&I.
· Create a new Inflow and Infiltration and Point of Sale Ordinance to help reduce the amount of the rainwater from entering the City's sanitary sewer system and reduce cost of treatment of clean water flowing to the NEORSD. This will include a penalty that will need to be discussed with City Council in a future meeting.
· Conduct a more a more detailed study of the two sub-areas identified as having higher I&I rates and identify potential sources of the I&I in these areas and work to eliminate them.
· Budget for the future medium- and long-term capital improvements as noted and in coordination with several upcoming large scale projects in the City including the second phase of 1st and Main.
Submitted by,
Jane Howington, City Manager
Thomas J. Sheridan, PE, PS, City Engineer
Bradley S. Kosco, PE, PS, Project Manager