What do you do when Consolidated Edison (conEd) shuts your gas service off due to a gas leak?
Introduction
In an effort to mitigate a potential gas utility shutdown, this engineering case study has been generated. This study will focus on the types of information and data necessary to ensure the completeness for each section of the project application, affecting engineering feasibility. The below points demonstrate the importance of this review:
Scope of Work
- Problem Description
- Proposed Solution
- Description of Existing Conditions
- Work Schedule
Cost Estimate
- Benefits of Conducting a Cost Analysis
- Engineering Cost for drawing preparation and filing
- Constructions Cost to erect/build what was designed
NY Engineers' Scope of Work
conEd shut down gas service for the entire building in this particular project. It was our goal at NY Engineers (NYE) to get the client's gas service restored as soon as possible. In conjunction with contractor oversight, NYE prepared drawings and filings to get this problem solved quickly.
The end goal was to restore building gas service to Hudson View Gardens, Building G, a 30,000 square feet residential building. This building consisted of 24 apartment units. Engineering plans were prepared and filed with the New York City Department of Buildings (NYC DOB) in order to conduct repairs and restore the aging gas piping infrastructure.
Problem Description
The apartment building demonstrated signs of a gas leak due to its aging piping infrastructure. To prevent any future catastrophe due to the hazardous nature of gas, the utility company conEd who services the building, shut down the gas service until repairs were completed and the building demonstrated no further leaks.
With the gas shut down in effect, this left the 24 apartment units with no gas for cooking, which led to a lot of upset tenants. Adding to the complexity of the project, each apartment had a separate meter which implies 24 gas risers. This meant each riser had to be tested for gas leaks and repaired, if necessary. A full passing pressure test of all gas piping was required for gas service to be restored.
Proposed Solution
Engage an Engineering Firm (NY Engineers) to create an engineered solution to repair and restore the gas service for the building. Any construction required to repair/replace gas piping must be filed with the NYC DOB and must be communicated to conEdison. This requires a licensed Professional Engineer to produce engineering drawings for filing and interface with the utility department.- Survey building to locate existing gas risers, meters, and valves. Capture location in order to produce plumbing drawings.
- Create process and guidelines for plumbing contractor to follow for testing and repairing the gas piping system.
- It is best to pressure test small sections of gas pipe to find the leak(s). They are typically around the valves and fittings, not the solid risers or branches.
- Best practice: replace all gas valves in each apartment serving the stove. The contractor must enter each apartment anyway to shut off these valves to perform pressure test. These valves are prone to failure; for another 15 minutes in each apartment they can be replaced to save contractors time from returning to the apartment to replace failed valves and minimize disturbance to the tenants.
- File the plumbing drawings with the Department of Building (DOB) in order for the contractor to acquire the necessary permits to begin work. Due to the urgency of the project, it was filed under directive 14 (professional certification), which allows 2-3 days plan approval.
- Coordinate with plumbing contractor and track the repairs/replacement of gas piping so it may be reflected on the plumbing plans.
- File the completed plumbing drawings as a post-approval amendment which reflects the proposed change/addition/integration of new gas piping to repair the leaks.
- Conduct weekly site visits and coordination with plumbing contractor to ensure/expedite the repairs and restoration of the gas service. Call conEdison on a weekly basis to inform them of the progress.
Description of Existing Conditions
Building G, along with its infrastructure, was constructed in 1925. The gas system was poorly maintained and the pipes began to deteriorate with age. During a field survey, it was found that the meters were locked due to conEd shutdown, determining that all shutoff valves were likely to be replaced, which they were.
Work Schedule
- Kick-off meeting with client and initial survey – 11/12/2015
- Plumbing Plans Complete and ready for filing – 11/16/2015
- DOB Approval Received, this project was filed Professional Certification – 11/20/2015
- Plumbing contractor pulled permit – 11/23/2015
- Plumbing contractor completed work – 02/19/2016
- DOB Inspection of plumbing work – 03/04/2016
- Post Approval Amendment Submitted to capture as-built conditions – 03/16/2016
- ConEdison restored/return gas service to building – 04/19/2016
Cost Estimate
Estimated cost to replace necessary piping and valves: $2,700
Engineering cost for drawing preparation and filing: $17,000
Construction cost:$68,000
Workflow
1. conEd shutdown
2. Engineering survey/strategy
3. Prepare/file engineering plans
4. Pressure testing/leak finding
5. Passing pressure test
6. As-built drawings/sign off
7. As-built drawings/sign off
