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Inflow and infiltration (I/I) is the excess flow of clear water into the City's sanitary sewer system:
Because the sanitary sewer system was not designed to handle this excess clear water, it becomes overloaded during times of high groundwater or heavy rainfall. This can cause basement flooding or bypassing of raw wastewater to local streams and lakes.
The excess clear water from I/I problems uses sanitary sewer capacity needed for wastewater. The result is sewer backups and increased costs (about $300 to $400 million annually) for needlessly putting clear water through the wastewater treatment process.
The Metropolitan Council Environmental Services (MCES), which provides regional wastewater collection and treatment for the metropolitan area, requires communities with excess I/I to invest in local reduction remedies such as disconnecting sump pumps and foundation drains from sanitary sewers and repairing leaky sanitary sewer pipes. Such actions will cost roughly $150 million, instead of the nearly $1 billion it would cost to build additional sewer infrastructure to provide capacity during big rain storms. To urge compliance, MCES incorporated surcharges for communities with excess I/I.
Golden Valley was identified as a contributor of excess I/I and is working to resolve the problem.
Although Golden Valley has led the Twin Cities metro area in reducing I/I, we are not the leader in Minnesota. Other cities (Duluth, Waseca, Glencoe, Hamburg, Tower) have been working for years to reduce I/I and continue to complete private property inspections as part of the effort. Once Golden Valley's City Council and staff understood the environmental, sanitation, and financial impacts of I/I, they committed to a proactive approach to reduce it. To track progress, staff monitors sewer flow at nine sites throughout the city and groundwater levels at seven sites. However, dry weather conditions in recent years make it difficult to document the true effects of I/I related improvements.
Golden Valley's inspection is required before a home that does not have a Certificate of I/I Compliance can be advertised for sale. Repairs should be completed, and a certificate of compliance issued, before the closing. If repairs cannot be made before a title transfer, then escrow is required. The certificate of compliance stays with the property after the sale.
After studying other programs, City officials concluded the cost of such a repair might be easier on homeowners at the time of a sale, when they typically have access to funding from home equity.
Repairs should be completed within 180 days of the first inspection, and the City can grant an extension of another 180 days. If repairs are not completed within one year of the first inspection, the inspection becomes invalid and the process starts again, which includes paying the applicable inspection fee.
Yes, if arrangements are made for escrow with the closing agent and an I/I Compliance Agreement is signed by the City and the responsible party. The seller is responsible for the initial inspection.
While some cities have been successful at reducing I/I, the regional problem is still significant and more participation is necessary. To enforce this, starting in 2013 MCES will implement a wastewater demand charge for communities with excessive I/I, including those with reduction programs. This means a city could get assessed a surcharge if it were to exceed sanitary sewer flow levels during a major rain storm, even if it had previously shown reduced flow rates through I/I mitigation.