Internal Water Main Design And Installation Explained By Balkan Sewer And Water Main

New Sewer & Water Mains, Subsurface News
January 13, 2014

by David Balkan

main line water work

An internal water main is required when a public water supply main does not front a building and the building is located inside private property. An approved water main, either public or private, is required in order for a tap connection to be legally installed and a water service line to be installed for a building. A water main is the main trunk line and a water service line is an individual service line for a building.

In some instances a public water supply main has to be extended down a public street when one does not front a property. But an internal water main is different, it is solely for mains installed inside private property. Also unlike an extension of a public water main, whose maintenance and repair reverts to the city, an internal water main remains the responsibility of the private owner. Interestingly if a meter inside a vault or hot box is required on the main line itself, the city does take over responsibility for its repair and maintenance. The original installation of the devices is at the owners expense.

Internal water main approval process

water tap
Service line tap connection

In New York City advanced approval prior to installation must be obtained from the Department of Buildings. A Licensed Professional Engineer (PE) or Registered Architect (RA) must draw up and submit plans for approval. An internal water main must have a connection at the public water main which is also a valve. It must have an approved valve and operating box within 2′ of the property line. Present rules also require that each separate building that receives its own water service line off of the internal water main  have an approved meter just inside the front foundation wall.

A proposed rule change will make individual service line meter optional at the owners discretion. As the City of New York will only read the main line meter, the branch line meters will only be used to determine an individual owners share of the entire NYC DEP water bill.

A tap connection required for each water service line will only be installed by the NYC DEP after a water test is performed. Water from the internal water main must pass a test to ensure that it meets NYC DEP purity standards.

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A proposed change to internal water main rules regulations

A Public hearing that was held on 12/23/2013 proposed changes to the metering and backflow requirements concerning internal water main lines. The cost implications to developers are substantial. This proposed rule change can easily add $30,000.00 to $40,000.00 to the cost of a project. Subdivision (b) of Section 20-03 is amended to specify requirements for approving new internal water mains, and to require that a property with an internal water main have a water meter and backflow prevention device placed at or near the property line. The proposed changes read as follows:

§2. Subdivision (a) of Section 20-02 of Title 15 of the Rules of the City of New York is amended to read as follows:
(a) Separate supply. A separate corporation stop (tap) and service pipe shall be installed for each building supplied with City water, except for buildings that have service pipes supplied by internal water mains as described in §20-03 (b). One tax lot cannot be supplied with water from another tax lot.
§3. Paragraphs 1 and 2 of subdivision (b) of Section 20-03 of Title 15 of the Rules of the City of New York are amended, and a new Paragraph 3 is added, to read as follows:

1) [Advance] Design stage approval for internal water mains shall be obtained from both the Department and the Department of Buildings. Approval for a meter shall be obtained from the Department’s Bureau of Customer Services and for RPZ settings from the Department’s Bureau of Water and Sewer Operations (Cross Connection Control Unit). Requests for approval shall be made by a New York State-Licensed Professional Engineer or Registered Architect.

2) Internal water mains shall have [either an approved valve and valve box or], in addition to any meters required by §20-05 (a), an approved meter and backflow prevention device in a meter [pit] vault or above-ground enclosure (“hot box”) installed [in] inside the property within two (2) feet of the property line [in addition to meters required by 20-05 (a)]. After installation, such meters at the property line will be owned, maintained, repaired and read by the Department. If a private street in a development remains privately owned, then the meter at the property line shall be used for billing and any individual meters in the development shall be deemed the owner’s submeters. If the City assumes possession of a private street in a development, then the meter at the property line shall be used solely for monitoring purposes and any individual meters in the development shall be used for billing.

(3) Design stage approval to install and repair internal water mains will be issued under the following conditions:
i) Owners of the internal water mains shall be responsible for their maintenance and repair.
ii) Internal water mains and any connections thereto shall be installed and repaired only with design stage approval, and may be inspected by the Department.
iii) Internal water mains shall be sized in accordance with the Department’s sizing table (Table #3) or as approved by the Department of Buildings. Where fire hydrants are required, internal water mains shall be a minimum of eight (8) inches in diameter.
iv) Internal water mains shall be controlled by a gate valve placed approximately two feet from the property line on the street side. A DOT-rated extension street box shall be placed over the gate valve. An additional gate valve and extension street box shall be installed for each three hundred (300) linear feet section of the water main and at each point where a lateral is connected to the water main.
v) Taps and wet connections to internal water mains shall be installed by the Department. The service pipes shall be installed by a New York City-Licensed Master Plumber with design stage approval to perform the work.
vi) Internal water mains must be disinfected in accordance with AWWA standards for disinfection of water mains, prior to being accepted for individual service connections or being placed into service. A water quality sample result acceptable to the Department must be obtained for internal water mains prior to placing them into service or issuing design stage approval for connection to such internal water mains.
vii) Written approval from the Fire Department is required before the Department may issue design stage approval of internal water mains. The key cost factor in the proposed rule change is requiring a main line meter  and backflow prevention device which is to be the same size as the internal water main. In addition the devices must be installed in an approved ‘hot box’ or underground access vault.

internal water main
Typical design of internal water main
meter access vault
Access vault and meter design

An actual internal water main installation

Internal water main installations are more technically challenging than a typical underground plumbing installation. The piping must be installed on a 6″ bed of crushed blue stone to avoid pipe settlement. In addition a filter fabric must be placed around the outside of the trench to hold the approved backfill material and crushed stone in place. These steps help ensure a long-lasting installation are required by DEP code. This and all such installations are subject to a careful step-by-step NYC DEP field inspection process.

Other technical challenges included ensuring that the main was contained inside the approved easement received from a neighboring property. An easement was required because the buildings to be serviced had no frontage on the street where the wet connection was to be installed. The wet connection for the new main was approved from a side street. The developer had to pay a fee to a neighbor to receive permission to run utility lines through their property and to allow for future repair and maintenance. Yet another unusual aspect of the installation was the requirement of an underground metering vault built to exact specifications. Inside the vault an approved water meter and backflow prevention device had to be installed.  Even a slight deviation in approved plans could result in the job failing to pass DEP inspection. These are a few reasons why an internal water main installation should be trusted to a highly experienced water main contractor.

sheeted hole
Location of future meter vault
open trench
Filter fabric for internal water main
main line water work
Main line gate valve

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David Balkan

David Balkan is the CEO of Balkan Sewer And Water Main, the largest and most trusted service in New York City. David is extremely active in various NYC plumber organizations being the Chairman of the Subsurface Committee in the Master Plumbers Council, and Vice President of the Subsurface Plumbers Association. In addition David’s expertise is respected by officials of New York City agencies such as the NYC DEP, NYC DOB, and the NYC DOT. He frequently provides valuable input on a variety of industry related matters.

Dave Balkan

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