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accompanied by active infiltration, and several defective service connections. The service <br /> area is mature and fully developed. <br /> 1.2.2 Conclusions <br /> Active infiltration is a concern due to the potential for void formation on the outside of the <br /> pipe. Such voids can lead to settlement, sinkholes, and unbalanced overburden <br /> pressures on the pipe itself. The capacity of the sewer is expected to be sufficient for the <br /> foreseeable future. Most of the sewer lies beneath improved streets and at such a depth <br /> as to require a complete street closure in the event of an emergency excavated repair. <br /> Pipe failure has the possibility of impacting the Decatur Memorial Hospital complex and <br /> nearby assisted living and skilled-care facilities. <br /> 1.2.3 Recommendations <br /> Eliminate active infiltration and repair service tap defects through a combination of <br /> trenchless rehabilitation and techniques and excavated repairs. Manholes should be <br /> treated with a spray-applied coating to stop infiltration and, if applicable, provide structural <br /> support. The estimated project costs for the McKinley Avenue Sewer are $583,300. No <br /> change to the annual O&M cost is expected. <br /> 1.3 71h Ward Sewer <br /> 1.3.1 Summary <br /> The existing 36-inch through 84-inch pipes of the 7t"Ward Sewer drain the southwest and <br /> center-west portion of Decatur, including Millikin University. Most of the pipes have a <br /> gunite liner that is eroding. Active infiltration and pipe defects are indicative of general <br /> age-related deterioration. <br /> 1.3.2 Conclusions <br /> Active infiltration is a concern due to the potential for void formation on the outside of the <br /> pipe. Such voids can lead to settlement, sinkholes, and unbalanced overburden <br /> pressures on the pipe itself. The capacity of the sewer is expected to be sufficient for the <br /> foreseeable future. The sewer often runs beneath residential and commercial structures. <br /> A pipe failure in the southwest comer of the 7t" Ward service area would cause CSO's <br /> and sewer backups in established residential areas. Pipe failure in the Millikin area would <br /> also lead to CSO's and would have the potential to cause severe damage to any of <br /> several university buildings. <br /> 1.3.3 Recommendations <br /> Eliminate active infiltration, structural and operational defects, and service tap defects in <br /> the existing pipes using trenchless rehabilitation techniques. Where it is cost-effective, <br /> traditional excavated repair or replacement should be considered. Manholes should be <br /> treated with a spray-applied coating to stop infiltration and, if applicable, provide structural <br /> BGM 11-050 Page 3 of 119 <br /> City Project 2011-03 Critical Sewers Rehabilitation <br /> Facilities Plan Amendment <br />