Title (30 pt Univers Ext) Subtitle (30 pt Univers Ext) Date (30 pt Univers Ext)

Bowers Hill Interceptor Force Main Section 1 Emergency Repair

August 26, 2014

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Break was identified on July 24 at 12:45 PM.Emergency Designation due to high riskExcessive rainfall during initial responseSpill contained 7am the next morningEvent overflow 919,500 gallonsComplex repair required 24/7 operation Repair complete in 9 daysForce main back online August 2Summary of Event2

36-inch ductile iron force main at the 337 Pressure Reducing Station - July 24

10 below grade - flow could not be diverted

High risk of a major catastrophic failure - immediately obtain Emergency Designation

Line stops, bypass, pumps, and engineering support

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Route 337 Pressure Reducing Station Service Area3

Route 337 Pressure Reducing Station near Chesapeake Square MallDescribe Service Area

Cedar Rd

Great Bridge BLVD and Battlefield BLVD3

Initial Conditions4

IDENTIFY THE BREAK SITE

Wastewater flowed into VDOT Storm water ditch to the right of the picture.

Initial spill estimate was 500 gpm

Crews responded immediately to assess situation and contain the leak.

Over 5 of rainfall in the 337 service area within a 24 hour period.

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Initial Dewatering Setup5

First day

Sandbags were utilized and a temporary pit was dug out for initial containment efforts.

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Initial Dewatering Setup (cont.)6

8 Diesel Godwin Pump mobilized

discharge through a flexible hose into the pressure reducing station6

Rainfall July 24-257

Over 5 of rain fell in the RT 337 service area that evening which doubled the flow for the service area and impacted the initial response Go over the 337 Service Area and that both Downtown Suffolk and Southern Chesapeake (Separate Service Areas) were also inundated7

Pressure Reducing Station (PRS)8

Simply Put a PRS Lowers Pressures on its Suction side to help upstream stations overcome friction losses in the Force Main8

Contingency Pumping and Dewatering System9

An Extensive Bypass and Containment System was built to recover as much WASTEWATER as possible.

Video Shows the contingency pumping and dewatering system 8 pump, 6 pump, 20,000 gallon sediment trailer, and 2 pumps and associated valving to pump from the sediment trailer to the PRS.

We were relying on the Pressure Reducing Station to maintain vacuum conditions to keep the spill contained for over 1 week.

If PRS pumps lost prime or additional force main failure occurred, pumping system would contain leak.

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Force Main Installed to Pump/Dewater to PRS10

This discharge FM from sedimentation tank hard piped to the Pressure Reducing Station

Fusing together approximately 100 of 12 HDPE and associated support and cribbing for the temporary Force Main. HRSD Employees put in many hours of hard work throughout this event. pumping out surrounding ditches, assisting TA Sheets and Godwin on equipment mobilization, emergency bypass pumping, and adjusting system set points. 10

1300 of Right of Way Widened for Equipment 11

Right of Way had to be widened and matting material installed to get specialized equipment in place.

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300 of 36 HDPE Pipe was Fused and Laid in 1 Week12

The entire area remained heavily saturated from the July 24th rain event

Over 300 of 36 HDPE Pipe had to be fused, set, supported, and tied in 12 hour shift rotations with a 12 man crew during the day and a 10 man crew during the night.4 excavators, 2 front end loaders, and multiple dump trucks worked 24/7 throughout the repair to accomplish this massive task.

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Upstream Line stop Excavation over 15 deep13

50 yards of concrete were used for Lines Stop Thrust Blocks *ADD Picture

Over 15 deep

Ground water was maintained with 5 diesel pumps

Incoming Groundwater varied from 500-2500 gpm throughout the repair13

Line stop Information14

Identify that because this system was a force main that there was no need for a bypass pump.14

Removed 36 Gate Valve and 12 of pipe15

Valve installed with dresser couplings on both sides

Bolts and nuts from the dresser couplings had completely failed

WR&A along with SPS performed an initial evaluation.

As bolts failed sewage may have leaked around gasket and created a corrosive environment within the poly wrap

Pipe had deteriorated between the weld on joints

Approximately 12 of pipe was removed.

Severe Corrosion was present on the pipe between the Mainline Valve and the welded-on restraint collars

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Pipe Failure16

PIPE IS LOCATED UPSIDE DOWN IN PICTURE

Notice the missing hardware from the dresser coupling restraints. 16

Pipe Failure17

PIPE IS LOCATED UPSIDE DOWN IN PICTURE

The upstream section of pipe had two 4 holes corroded completely through the pipe wall. Deteriorated components were replaced with new pipe, valve, and ductile iron sleeves.

Cathodic Protection was designed and installed for this site.

This is the failure location on the upstream piece of pipe from the Mainline Valve. There were two 4 holes located at 5 and 7 o-clock. It was observed that the ground water level was at the same elevation as the failure.17

New 36 Plug Valve, DI Pipe, and Solid Sleeves were installed 18

Solid Sleeves, instead of dresser couplings, were installed with a new Plug Valve and piping.18

Future Inspection Sites19

HRSD has identified 6 other locations on the Bowers Hill Interceptor Force Main Section I and II that similar installation methods were likely used.

These Pipes were Relocated back in 1988 (26 years ago) for the construction of Interstate 664

Brown and Caldwell will be leading the effort in future condition assessment and related analysis.

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Questions?

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