I&I (Infiltration & Inflow)

Sources of un-permitted “storm” water are classified in two categories; Infiltration & Inflow (I & I). INFILTRATION refers to more inadvertent sources such as cracks in pipe and INFLOW refers to more direct sources such as downspouts, driveway drains, and sump pumps. Whether purposely or inadvertently introduced the draining of surface and/or ground water in to the Sanitary Sewer System it is a Violation of Highland’s Rules and Regulations, and must be corrected and eliminated.

The Authority continues to conduct an extensive and aggressive Rehabilitation Project throughout its sanitary sewer system. This approach is two-pronged: 1. Investigate, locate and repair or replace identified sources of I & I on the Authority owned sanitary sewer system, AND  2. Proceed throughout our service area on a drainage basin by drainage basin approach whereby annually customers within a specific drainage basin are required to pass a Pressure Test unless they have passed such a test within the past 15 years. Our progress and results are monitored by the Pennsylvania Department of Environmental Protection (PaDEP) via bi-annual reports submission by Highland. The PaDEP restricts or prohibits further development based upon our documented efforts and results. Historically, during severe precipitation events the sanitary sewer pipe network becomes overloaded, causing basement floodings, discharges to streams and watercourses and/or overflow out of manhole lids. In addition to being unsanitary such surcharges and overflows are a violation of State and Federal law. The cause of this overloading is the introduction of surface water and ground water, either inadvertently or on purpose, into the sanitary sewer system. The sanitary sewer system is not sized to act as a “storm sewer system”. Storm sewers are an entirely separate pipe network.

Highland operates a 5-man “I&I Crew” solely devoted to identifying and removing I & I sources on the Highland owned system. Additionally, Highland awards Contracts (via a public bidding process) to construction firms for various sewer rehabilitation pipeline projects. Over $24 million has been expended to date. However, it is important for all customers to realize the amount of underground and under slab piping they have on their own private property. Including the piping buried under the basement as well as that out in the yard an average home/customer may have 102’ of pipeline located on their property. In fact, Highland’s sewer customers own/control nearly as much pipeline as does Highland. Highland has approximately 120 Miles of Mains and Laterals. It is estimated the Customers combined piping totals over 107 Miles. Understandably then, our customers need to be a big part of our I & I reduction efforts. That 102’ of pipeline on the Customer’s property could have multiple sources of I & I.

An example of common defects/violations on the Homeowner’s lateral system are shown on the diagram below: