Achieving A Successful Expedited Emergency Response Without Sacrificing Safety Considerations
- Kenneth Morairty, Heather Belovin, Matthew Osit - Bureau Of Engineering, Design and Construction, New York City Department of En
- Eric Klee - Bureau Of Wastewater Treatment, New York City Department of Environmental Protection
- Eamon Kelly, Jon Pepe - Hazen and Sawyer
The Bowery Bay WWTP is a 150 mgd dry weather, 300 mgd wet weather secondary treatment plant with step feed BNR located in Northern Queens, NY. Incoming flow from two interceptors is handled through two internal pump stations that is then pumped through three buried pipelines to a flow structure where the combined sewage is distributed to multiple treatment trains.
Header A is the main and largest of these three pipelines, with a maximum diameter of 102 inches and a typical daily flow of 100 mgd.
On a Sunday morning in February 2015, the watch engineer observed a flow bubbling from the asphalt above Header A as it exits the pump station. Even though the pipe is located 25-feet below grade, upon confirming the leak was sewage, the emergency response plan was put into play, requiring the isolation of the leaking pipe.
By utilizing temporary submersible pumps in the existing wet wells and modifying the existing main sewage pumps, High Density Polyethylene Piping (HDPE) cut and fused to length onsite as the discharge pipes allowed the solution to be implemented immediately.
Planning the Work
Once we decided how to fix the leak and what approach we were going to take, we needed to make sure the work was going to be done safely, without any environmental impacts. Luckily we already had programs in place and we were able to quickly review and develop plans to address the risks from the emergency work. The contractor’s Environmental Health and Safety Plan was in place from a concurrent project and was carefully reviewed for relevance to the work activities required during the emergency response. Gaps in the EHASP were addressed with specific Job Hazard Analysis. JHA’s are developed to target specific work operations, many of which are unique in nature.
The team didn’t do anything unusual in keeping safety at the forefront of the planning during the emergency response, rather we just implemented the training and protocols outlined by BEDC in their safety roll outs. The team was successful in implementing the game plan with only a few audibles called here and there due to differing field circumstances. Coordination and communication was going to be instrumental during the emergency response effort. Daily Work Activity Briefings were held to disseminate information amongst team members. As the high risk work was identified and after the JHA’s were developed with the entire team including the Workers, we met each morning and each afternoon for a recap.
All aspects of the work involved in depth review of safety requirements. Lockout/tagout, confined space entry and critical lifts as well as many other safety standards were reviewed. Each activity presented a new and unique challenge to the team that tended to differ from typical isolation/confined space work methods. The team recognized, that given the nature of the work, without implementation of detailed safety protocols initiated by senior management, rather than leaving safety planning to the discretion of the rank and file, the potential for accidents and injuries was great.
Below we will review some specifics of how we were able to identify some of the riskiest portion of the work and what steps we took upfront to ensure we achieved a successful expedited emergency response without sacrificing safety and environmental considerations.
The contractor had labor forces, equipment, HDPE piping and pumps on site within three days of the emergency declaration and immediately set to work. During the scramble, and as material and equipment began to arrive on site, the team had to establish material laydown areas, routes for the temporary pipelines, and identify and exclude areas of the yard due to its potential for collapse from undermining. As this was emergency work, the planning strategy tends to differ from standard construction planning. During this process, it became evident that sections of the plant requiring regular access were going to be isolated and that there were going to be work activities required that were not part of typical heavy construction. Coordination and communication protocols were setup immediately.
As the existing headers are underground, when installing the bypass piping on grade, the available site work areas got crowded quickly. Plans were immediately implemented to provide contractor assistance to access these isolated areas. The team had identified this risk and had to quickly develop safe access for workers, operations and project staff. This was discussed with everyone so they knew the safest access points to the area. In this example, the temporary piping impeded access to one of the plant’s entrances. You can see the access ramp the contractor installed to address the risk. Note that the pipe also impeded access to the plants’ screening containers.
The typical operating procedure when moving a loaded screening container involves pulling its cart to a pickup location, utilizing a fork lift. During the emergency situation, under consideration of site infrastructure conditions and that time was of the essence, the temporary piping installed on grade did not allow the use of the forklift to relocate the containers to the pickup area. Alternate equipment was needed to hoist the container over the HDPE pipe interference.
During one of the first attempts to hoist the containers over the pipe, a worker was injured. A lull was utilized to lower the container onto its cart. As the forks were removed, the cart began to roll. A worker nearby reacted, reached out and grabbed the container at the same time the lull operator lowered the forks to stop the movement of the container. The worker’s hand was pinched between the machine and the container. He was taken to the hospital and returned to work the following week. In this instance, the lines of communication failed as a work plan had not yet been established.
At the time of the accident the contractor, plant operations and construction management were meeting and developing JHAs and work plans for the many activities that needed to take place, including the relocation of the screenings container. However the workers attempted to perform the task in advance of receiving the JHA without proper planning or training. The work activity was stopped and the team immediately gave a higher priority to the work associated with the screen container relocation activities.
As a result of the work plan review, the team required a forklift be placed inside the barricaded area to properly move the screenings containers to the pickup zone. In addition, a crane was required to be used to lift the containers over the pipe obstruction. A second forklift was then waiting on the accessible side to receive the container. The workers’ involvement, and hence risk, was now very limited. Plant personnel and the contractor coordinated the effort to make it into a well-rehearsed operation.
Although the goal as always is no accidents, no harm to people and no harm to the environment as stated in BEDC’s EHS Policy Statement, there unfortunately was an incident. A lesson learned from this incident is that an emergency situation does not mean to react or rush in – stop, take a timeout, and establish a clear plan before proceeding. Each operation was planned in conjunction with Plant Operations to address maintenance and operational concerns. Once those parameters were established, the actual logistics planning started by addressing all safety risks associated with the operation. If the safety review revealed that the risks were unacceptable then alternate methods were discussed with all team members, including the operating staff, and the plan was revised until the required objectives could be obtained safely.
Emergency Response Highlights
Now we’ll go through some Emergency Response Highlights. As part of the temporary pump installation, two (2) pumping units were required to be installed in the plant’s low level wetwell. The low level wetwell is 50 feet deep with an access opening that is 20 feet wide. Entry into the wetwell is from grade and required the use of a series of ladders. Divers were required to perform the work as the wetwell could not be dry. The work had to be carefully coordinated with plant operations as the wetwell had to be isolated and equipment shutdown with appropriate lockout/tagout while work was being performed.
Part of the BEDC confined space protocol is to contact the FDNY prior to entry in order to advise them that work was being performed in a confined space. In case of an emergency, dispatch would already be aware that a rescue team was needed. During the establishment of the work plan, the team reached out to the FDNY and requested a site visit. During the visit, the FDNY requested it return with multiple teams as any wetwell rescue posed unique challenges – they even performed a mock rescue setup to ensure the equipment they had would be able to be used to assist.
And since the access point of the wetwell was between two buildings – the crane was required to setup on the outside of one building with the pumps and piping setup on the other side of the other building. That required the crane operator to perform the work blind, by radio communication only, to get the material where it needed to be. In this case we also had the high hazard work being performed at night. The operation was a success and the planning and decision process worked.
In order to isolate the Main Sewage Pump discharge header in the yard, a 102-inch diameter concrete plug along with a 20-foot tall bulkhead were required to be installed in the flow division structure. Access into the FDS is from above, from an opening that’s 12-foot by 8.5-foot. The structure is 30-feet deep and has a sloped bottom. Planning and coordinating the shutdown of the structure for the lockout/tagout of the existing feeds and confined space entry requirements were essential in performing this work. Again the FDNY conducted a review of the area to be familiar with the structure and be ready to assist in case of an emergency.
A safe work plan was established to facilitate the work. Lock Out/Tag Out presented its own unique challenge due to the fact that this structure distributes the flow to the rest of the plant which had to remain in operation. As with confined space entry requirements, continuous air monitoring and the assistance of forced air ventilation were implemented. In addition, fall protection measures were established to safely utilize a series of ladders and work platforms to perform the work.
In the next example, to activate the Gravity Thickener Overflow bypass pipe, an existing 48” valve needed to be closed. Plant operations attempted to close the valve and it was determined that the valve would not seat properly. Further review of this pipeline indicated there was the possibility of rags preventing the valve from closing. There is a 48-inch end cap on the pipeline and the valve is located 18-feet inline. Lock Out/Tag Out and confined space entry reviews commenced with the intention to enter the pipe to manually clear the valve of the obstructions.
A thorough review of all connecting pipelines and systems provided the necessary lockout/tagout requirements. As the pipe itself is a confined space, all appropriate measures for confined space entry were also reviewed. In this scenario, 28 locks were required to be installed to isolate all possible energy sources. The team continued preparations by performing mock walkthroughs of the entry and clearing operation. During the coordinated shutdown, the valve obstruction was cleared and confirmed closed prior to closing up the pipeline and restoring service.
A portion of the plant’s discharge Header C also required isolation. As this pipe needed to be plugged for a short period of time to perform a specific repair, time was of the essence which did not allow for removing a portion of the 48-inch pipe itself. Again, reviewing all potential energy sources, entering the pipe to install the 48-inch plug became a feasible solution. The team understood the dangers and difficulties associated with entering the pipe and again were able to engineer out the hazards. By removing smaller 6-inch appurtenances such as vents and drains that were on the line, this created access for light, forced air ventilation and ropes to enter into the pipe to assist with the install.
The team is proud to report that after 30,000 hours of work and a dozen confined space entries and critical picks, that the leaking pipeline has been isolated, bypass pumping is maintaining the plant’s permit requirements and the only injury sustained was the one that occurred in the first month of the emergency response. This demonstrates that even in emergency responses, where time is of the essence, making safety a priority does not have to impact the speed or efficiency of the work performed.
For more information, please contact the author at email@example.com.
Hear about new publications with our email newsletter
Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.