Commission Agenda Item #8 Award Contract C02009P01 Engineering Services for H2S and Odor Mitigation Planning Study Project Commission Agenda Item #8

Background Odors are present in wastewater Sulfides can cause odors & corrosion in sewers Sulfides can be converted to H2S & sulfuric acid H2S is dangerous and can cause death in high concentrations

Background (continued) Dozens of locations in conveyance system: Odor complaints Corrosion issues Current response is to rehabilitate known corroded structures, sewers, gates Need an overall plan for mitigating odors and corrosion in MMSD system Sustainability consideration in odor and H2S treatment system

So this is a picture from the Southwest interceptor pipe taken in 2015 So this is a picture from the Southwest interceptor pipe taken in 2015. The pipe is 16” thick monolithic concrete, meaning no reinforcing steel. During construction of the monolithic concrete pipe they install a water stop at about 8” of pipe thickness. That waterstop is what is hanging down in this picture. If that waterstop was installed in the correct location, we have lost well over half the pipe thickness in this segment of the pipe. This picture is taken about 27’ from MH 41703 which is located in STH 100 and College Avenue in Hales Corners. This is showing the damage that can happen to pipes from H2S, but we need to make sure the damage is critical and what types of repairs are best to make responsible financial decisions on project. Asset management and planning can determine the risks associated with these types of damage to give Budget the tools they need to financially assess projects.

This is a close up of the water stop, but you can see the concrete pipe deterioration that is occurring. The H2S is converted to sulfuric acid which eats away at the cementitious portions of the concrete, leaving the exposed rock, which will eventually fall into the sewer stream.

Project Scope Address known areas of concern Determine where additional areas may develop Develop lifecycle costs for odor and H2S treatment systems Undertake Envision sustainability review of treatment options Conduct vapor and liquid phase testing Write planning study

Project Cost/Schedule Request for $337,998 Project complete in 13 months Project within budget Project negotiations added additional scope due to the requests by VWM due to the foaming issue, we added these to our scope instead of VWM doing the work.

QUESTIONS?