During the week of June 26, 2017, Delmont Borough’s public works crew, together with personnel from Tri-State televising, were on site to inspect the condition of the Borough’s 8-inch gravity feed line from the Delmont Borough-Salem Township border through to the Cramer Pump Station located below adjacent to the Beaver Run.
A line sag identified several years ago during a previous televising was confirmed during the current inspection; several additional areas of line sag were identified during this most recent televising. At the July 11, 2017, public meeting of Delmont Borough council, the Borough’s consulting engineers refused to respond to a suggestion that excessive storm water run-off from the Borough directly onto the subject property has caused significant soil instability, a condition likely contributing to these multiple areas of line sag.
As a result of the televising, an “ovaled” section of the gravity feed line was replaced in an area where a natural gas line crosses well under the Borough’s sewer lines. While the Borough’s consulting engineers expressed that the installation of the natural gas line was the probable cause of the “ovaling” of that line, and suggested there may be recourse for the Borough against the gas company, it is possible that the “ovaling” of the sewer line was caused, or was in part caused, by the seismic loading effect of: (a.) excessive storm water run-off from the Borough directly onto the subject property, causing soil instability along the Borough’s sewer lines, and (b.) storm water inflow and infiltration originating in the Borough and entering the Borough’s sewer system, causing a hydraulic hammering effect along and between the individual sections of line during times of high volume and pressure.
Note that the Borough’s sewer system is not designed, and is not permitted by the PA DEP, as a Combined Sewer System designed to collect surface storm water run-off.
Also replaced the week of June 26 was a lateral service connection that was compromised and experiencing ground water seepage. This lateral connection is the last along the gravity feed line above the manholes that have experienced, and continue to experience, Sanitary Sewer Overflows (SSOs). It seems likely that the high pressure and high volume hydraulic hammering effect of storm water inflow and infiltration originating in the Borough, that makes its way into the gravity feed lines not designed or intended to carry such inflow and infiltration (surface storm water run-off), combined with the fact that the Borough’s storm water run-off directly onto the subject property has caused the tributary in the area of that lateral connection to move 20 feet in 15 years, has contributed to the compromised service connection.
The Delmont Borough public works crew also undertook to re-stabilize a manhole that had canted sideways, likely as a result of the excessive direct storm water run-off, excessive forces within the system caused by storm water inflow, and SSOs experienced at that location and from that manhole, creating soil instability.
To our knowledge, the Borough has not yet determined a course of action with regard to the other areas of sagging along the gravity feed line as detected by the most recent televising but not addressed the week of June 26. However, we are assured that the pipe sections are connected and functioning well, as evidenced by the duration and volume of discharges during periods of even moderate rain from the manhole stack located downstream beyond the sag locations. Note that this is the same manhole stack that was sealed by the Borough on April 27 and subsequently unsealed immediately prior to an anticipated heavy rainfall of June 23. The manhole stack was “unsealed” by Delmont Borough immediately prior to that heavy rainfall in order to prevent raw sewage discharges from other manholes further up the line, thereby forestalling contamination of new areas of property that have not experienced such contamination in the past. Over that 2-day period (Friday into Saturday, June 23 to 24), raw sewage discharged unabated directly into the Beaver Run – the local community’s municipal water source – for more than 24 hours at that manhole stack location.
Delmont Borough’s inspections and repairs to the lowest elevation section of its sewer system – while necessary, normal and routine, as with any sewer system – do not address the larger root causes of the Borough’s sewer collection system infrastructure instability: storm water inflows and infiltration originating in the Borough into a system not designed or permitted to collect surface storm water run-off; excessive storm water run-off from Delmont Borough directly onto the subject property; and the compromised force main (that takes the sewage from the Cramer Pump Station back up the hill and over and down to the Franklin Township Municipal Sanitary Authority in Murrysville for treatment) that has experienced multiple leaks and which the Borough refuses to pressure test, which test would allow for an accurate determination as to the full extent of the issues it faces with that portion of the system.
With regard to the gravity side of the system, it would seem the most logical course of action would be to focus first upon identifying and mitigating the direct inflows into the system at the highest system elevations within the Borough itself while also sealing any identified leaks or loose connections – in order to minimize infiltration – and then to work down the line toward the pump station, rather than the Borough’s stated current plan to “work its way up the line” from the bottom of the system.