Sunnyland has been selected for the Central Basin Inflow and Infiltration project due to the way the system is built in it. The straight sewer mains collects together at the south end of the neighborhood which allows easy monitoring of the flows and measuring the impact of the project on reducing unwanted water.
43 percent of 342 affected property owners in Sunnyland have signed a side sewer replacement agreement which gives the city and their contractor permission to do sewer work on their private property. Craig Mueller, project engineer of the Central Basin Inflow and Infiltration project, is looking for 75 percent and more to achieve better results for studying.
The Central Basin Inflow and Infiltration project is a pilot study to determine the effectiveness of addressing private sewer services [the pipe from a house to the sewer main] and the main piping and manholes.
Inflow and Infiltration is the problem of excess water that flows into sewer pipes from groundwater and storm water. Groundwater [infiltration] are water that seeps into sewer pipes through holes, cracks, joint failures and faulty connections while storm water [inflow] flows into sewers from roof drain downspouts, foundation drains, storm drain cross-connections and through holes in manhole covers.
According to Mueller, the central basin area is divided into two areas, the pilot area and the control area. The areas have flow monitors installed to record volume of flows. Also, the pilot area will receive new sewer main piping, manholes and sewer services.
Property owners who signed the replacement agreemnt will have their pipes replaced known as pipe bursting, a trenchless technology method.
“A hole is dug on each end of a pipe to be replaced and a cable run through the existing pipe. The cable pulls a new pipe through the existing pipe, shattering the existing pipe as it goes through. Using pipe bursting, nothing gets disturbed between the two holes which is important due to all the decks, fences and garages that are built over the sewer services,” Mueller said.
The side effect of this technology is temporary noise and access disruptions from construction. As physical work has to be done, each property is disconnected from their sewer for no more than eight hours while it is being service. As the sewer service takes place only at specific area, impact will only be to one specific block for about week. Property owners do benefit from the service as well. The pipe replacement will provide a lesser chance of potential sewer backups into their homes and no cost is included with the project. Each property also receives a new sewer service at no cost which if fails outside of the project, can cost the property owner about $3,000 to repair.
“Most sewer mains were built between 1905 and 1910 and they are in poor condition. City permit records indicate many property owners applying for permits to replace their sewer service over the last 15 years, still have the old sewer services made of clay pipe,” Mueller said.
The aging infrastructure on public the aging infrastructure on public and private property resulted in Inflow & Infiltration thus maintenance and replacements are needed. The excess water also contributes to increase treatment costs at the Post Point Wastewater Treatment Plant.
On a dry day, the Post Point Wastewater Treatment Plant treats eight million gallons of wastewater, on average. And on a rainy day, the amount can increase to 72 million gallons per day. The excess water comes from the Inflow and Infiltration sources.
“The cost for this is borne by everyone who pays a sewer bill in the form of higher rates,” Mueller said in the email.
Once the flow coming into Post Point Wastewater Treatment plant exceeds the capacity of the plant, the wastewater bypasses it and is discharge to the bay untreated.
The project seeks to find property owners who are willing to volunteer with the project to gain better results from studying the Inflow and Infiltration and to help the neighborhood solve the untreated discharge excess water.
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