Small Reservoir

Document Overview

This is a formal letter from the engineering firm Stiffler McGraw, submitted on behalf of Ebensburg Borough to Brandon Frey at the PA DEP Division of Dam Safety. The letter covers the 2023 Annual Reservoir Inspection for Howell’s Run Dam (DEP File No. 11-103).

Inspection Summary

The inspection report indicates that the dam appeared to be in good condition overall. However, several specific issues were identified that require attention or monitoring by Borough staff.

Key Observations and Required Actions

• Foundation Drain Erosion: Seepage is flowing behind the weir plate in the eastern spillway wall, eroding the concrete at an increasing rate.
  • Action: The weir plate should be removed in the short term to minimize concrete deterioration.
• Vegetation Management: Areas on the downstream embankment and upstream slope are overgrown with brush and woody growth.
  • Action: These areas need to be cut/cleared. This includes the left abutment and outlet headwall.
• Animal Burrows: Two notable animal burrows observed in 2022 could not be located in 2023 due to high brush, though they are suspected to still be present.
  • Action: Burrows should be located and filled to prevent further damage.
• Wet Areas/Seepage: Two new wet areas were identified in 2022 (east and west of the stilling basin). A "swale" of wetness also extends parallel to the western spillway wall.
  • Context: These areas were likely wet in past inspections but could not be thoroughly observed due to thick brush.
• Pipe Maintenance: Inlet ends of corrugated steel pipes through the stilling basin wall need clearing of silt and debris. The ends are corroded.
  • Action: Consider repairing or replacing the pipes.
• Monitoring Required:
  • One of three typically wet areas along the downstream embankment was wet this year; continue periodic monitoring.
  • Seepage weirs at the outlet works headwall should be monitored.
  • Seeps on the western spillway wall were wet this year; continue monitoring.
• Concrete Joint Separation: The concrete joint where the eastern spillway wall meets the stilling basin overflow was notably separated this year, with water flowing through it. The next joint down is also beginning to separate.
• Pipe Opening Status: A small pipe opening on the western spillway wall (identified in 2022) is now mostly closed due to fill material. It should continue to be monitored.
• Exposed Rebar: Small portions of exposed rebar were identified on the downstream face of the spillway ogee wall.
• Valve Operation: The primary closure valve should be operated prior to next year’s inspection.
• Security: A lock should be installed on the gate across the access road.

Additional Notes

• Brush Clearing: The report strongly encourages Ebensburg to clear thick brush annually and prior to annual inspections. This was necessary in 2022 to make detailed observations of wet areas, burrows, and joint separations.
• 2022 DEP Review Letter: A separate page in the document notes that the "DEP Review Letter for 2022 Inspection Report" was not received.

Signatory

• Tyler M. McGraw, P. E.
• Project Engineer, Stiffler McGraw