Surrey has an annual program to rehabilitate its sewer mainly to reduce the extraneous inflow into the sewer system and to prevent the premature failure of the sewer system. Groundwater enters the sewer system through cracks, joint displacement in the sewer pipes, connections, building sewer sand appurtenances. Rainwater can also enters the system if the building rain gutters and foundation soil drains are connected to the system. Discharge rainwater to the sewer system is illegal and will be fined if owners do not disconnect their rain gutters or soil drains to the system.
Every year City assess by flow monitor the extent of this Inflow and Infiltration (I&I) by catchments. The severity of this Inflow and Infiltration (I&I) will be ranked and rehab work on the most severe catchments. Normally these catchments are in the older sub-divisions serviced by brittle pipe materials or in areas with high ground water table.
Rehabilitation consists of pressure testing and grouting failures, utilizing trenchless technologies for cost-effective replacements or open-trench replacements. Holes on the manhole covers are plugged to eliminate the chance of clean water inflow. Reducing this extraneous inflow will save money for the community as the treatment plant and trunk sewers need to be upgrade to handle this additional wet weather flow. Wet weather flow can exceed twice the dry weather flow. In addition, reducing the wet weather flow will mitigate the sanitary sewerage overflows.
Below are photos of Pipe Bursting trenchless technology
However, 30% to 70% of the Inflow and Infiltration (I&I) is from the private laterals (building sewers). Owners are responsible for repairing or replacing their building sewer such that no rainwater or groundwater enters the system. City has initiated a policy requiring all connections that are 30 years old or older be replaced when the lot is developed.
Owners can further assist the community by: