Case study narrative
Project narrative
Manholes are an important part in the proper functioning of the wastewater collection system. Most manholes were constructed with mortar and brick or stone, and have not been rehabilitated since their construction, even those built in the 1800s.
Manholes are starting to get mortar joint cracking and leaks from normal wear and tear, water inflow and infiltration of roots and debris. Some of the manholes may also suffer from the effects of the freeze-thaw cycle, poor construction, and overuse from population expansion. Manhole Rehabilitation is to help resolve issues such as eliminating inflow and infiltration and improving structural integrity and corrosion protection.
7NT Engineering was awarded the Citizens Energy Group (CEG) Manhole Rehabilitation Project by CEG for the fiscal year of 2020 and 2021. This is an over two-million-dollar project under the Capital Program for Manhole Rehabilitation in Indianapolis, Indiana. For this project, 7NT has worked on rehabilitating over 440 manholes in the Indianapolis area and continues to work on the rehabilitation.
7NT was given thirteen assignments in 2020 and three assignments in 2021.
For all the projects, 7NT provided required maintenance of traffic and obtained required permits for the work, clearing site, and site restoration.
Scope of work
Technical scope
Manhole rehabilitation scope
- Interior manhole lining
- Channel and bench reconstruction
- Chimney and riser reconstruction
- Grout seal installation
- Frame and cover reset
- Raising manholes to grade
- Interior manhole lining with corrosion protection
- Sewer bypass
- New internal drop installation
- Adjacent concrete culvert restoration
- External drop plug-off
- Structurally damaged barrel section replacement
- Jet sewer due to blockage
- Erosion control
- Weir and fillet installation to direct flow
- Trench box setup
- Flowable fill backfill
- Sewer and storm line extension to new manhole
- Lid installation, bolt securing, and ring/frame adjustment