EBMD and HEB Filing 9 North Underdrain Project

The Eagle Bend Metropolitan District (EBMD) recently completed the foundation underdrain realignment project for HEB Filing 9/HEB North at Heritage Eagle Bend (HEB). Construction of the project, by EBMD, was completed on August 23, 2013. The HEB Master Association is responsible for the final phase which includes: sealing the existing pipe which was cut off and rerouted by the EBMD to ensure the pipeline stays contaminate free, and removing all debris emitted from the pipeline.

PowerPoint Presentation 2013-08-22


First, a quick review of the project.  HEB North is a multi-family development which includes a foundation drain for each of the structures/homes.   These underdrain systems are designed to carry water away from the perimeter of the foundations.  In order to accomplish this, the foundation drains were originally designed and constructed to follow the sanitary sewer lines in the subdivision until a point where the underdrain could be extended to reach “daylight”, meaning above natural grade.  In the case of HEB North, this occurred in the cul-de-sac of S. Addison Court.

At some point in time, it became apparent that a portion of the underdrain system had failed.  Problems appeared to be isolated to the S. Addison Court section of the system.  The failure allowed groundwater, sometimes containing certain contaminants at concentrations exceeding levels permitted by the Clean Water Act, to enter the system.  This discharge was brought to the attention of the City of Aurora and the Water Quality Control Division of the State of Colorado, who in turn approached the HEB Master Association (HEBMA).  After several studies and attempts to repair the failed pipeline, it was proposed by EBMD, and accepted by HEBMA, to abandon the failed line in S. Addison Court and find an alternative means to deal with discharges from the drains.

The design of this project was approved by the COA and reviewed by the State of Colorado.  Since failures appeared to be isolated to the outfall pipeline under S. Addison Court, the District had an opportunity to intercept the pipe downstream of where the foundation drains were attached but upstream of the failed sections.  This occurred on S. Biloxi Way between Addison Way and S. Addison Court.  Fortunately there was an existing storm drainage system in the area which could be connected to and convey the drain water above grade. The underdrain system is about 28 feet deep; approximately 22 feet lower than the storm drain system. A pump was required to bring the discharge from the underdrain system up to the storm drainage system.
The existing underdrain system was intercepted near the middle of the intersection of S Biloxi Way and S. Addison Way. It was then redirected to a manhole located on the southwest corner of that intersection.  Float switches control the operation of the submersible pump located in the manhole. Water collects in the manhole until the water level rises above a “start” float switch and the pump runs until the water level drops below the “stop” float switch. The pump discharges to the storm drain inlet box located approximately 6 feet from the manhole below grade.  From here the discharge is conveyed to daylight by the existing storm sewer system.

The pump rests near the bottom of the 30 foot deep manhole and is supported by a slide rail system that allows for removal of the pump for repair or replacement. A backup pump was provided to the HEBMA.  A cell phone based telemetry system was installed to monitor when the pump starts and stops and also to alert District and HEBMA staff if the water level in the manhole rises above the “high level” alarm float switch.  Even with the recent heavy rains, the pump was able to keep up with peak flows. There have been no high level alarms.  Once the HEBMA completes their portion of the project the COA and State of Colorado will determine whether HEBMA has remedied the problem as outlined by the COA and State.

  Project Photographs          




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