When a new house sewer is installed in NYC there are 6 basic types of sewer connections that meet code requirements. The most usual is the spur connection, and a spur is also the least costly to connect to when it is available. However, as time has passed it is more and more usual for building lots to be split. This creates new buildable lots, and decreases the availability of spur connections. Another factor involving the availability of a spur connection is when previously undeveloped land is developed.
Due to the above factors, more often than in the past other types of house sewer connections have to be utilized and built.If you are developing a property in NYC it is important to familiarize yourself with these connections as they can add substantial cost to a project. What follows is a description of the 6 types of sewer connections used to connect a house sewer to a city sewer.
1. Spur connection
A spur connection is the most common of all connections used for a house sewer. Basically a spur on a city sewer is a wye in the city sewer with a plug on the outlet side. The plug is removed when a future house sewer connection is made. The spur itself is typically 6″, with the exception being 8″ sizes in Manhattan. This is because the minimum size for a house sewer in Manhattan is 8″.
2. Fold in sewer connections
When the city sewer is only one size larger than the connection size required, and no spur exists, a sewer contractor must fold in a new spur in most cases. This typically occurs when the public sewer is 8″, a size no longer legal as a public sewer in NYC, and a 6″ connection is required.
A fold in requires actually removing sections of the city sewer, then folding in three new sections of pipe one of which is a wye to be used as the connection for the house sewer. All new sections of pipe must then be encased with an approved concrete mixture. A new fold in connection adds to the cost of a new sewer installation.
3. Curb connection
A curb connection is usually found on two occasions. A curb connection avoids the need to open the roadway in order to complete a sewer installation. The first case is when a new public sewer is installed. Frequently as part of the new public sewer project a new pipe is installed up to the curb line for each building, and also for buildable lots that have not yet been developed.
The second case where curb connections are found is when a previous building has been demolished and the service for that property was plugged at the curb line, as is required by code. When a property is redeveloped a plugged curb connection can be frequently re-used at a substantial savings to the property owner.
4. Drill in sewer connections
When a new connection is required into a NYC sewer and no connection is available, the most usual connection required is a drill in. This is performed using a core drill machine. It is not permitted to chop into a NYC sewer using hand or power tools.
A hole is carefully cored through the NYC sewer a specific size larger than the pipe size to be connected. In most cases the city sewer must be prepared before the core drill is done by encasing the public sewer in concrete. In other cases a concrete cradle must be installed under the public sewer. The concrete reinforces and strengthens the city sewer from the added stress of the core drilling and the future house connection.
5. Riser connection
A riser connection is a vertical connection built on the top of a city sewer for use as a connection for a house sewer. Depending on the size and type of the public sewer different designs are used in the construction of a riser.
When is a riser connection required?
It is usual for a riser connection to be required when the depth of the public sewer is greater then 13′. A riser connection can also be required if a groundwater or a rock condition exists. In these cases it is meant to alleviate the cost to property owners of having to excavate to great depths, or through groundwater and rock, in order to connect properly to the main sewer line. If a future sewer repair is needed, a riser also lowers the cost at that time as well. A riser is also required when the difference in elevation from the point where the house drain exits the building to the city sewer is greater than the pitch that is allowed to be used. As sewers work on the principal of gravity, pitching the pipe is used so the waste-water runs off properly.
Only a maximum of 1′ of pitch is permitted for every 4′ of run of pipe. Therefore a riser must be built sometimes when the difference in elevation is too great to use allowable pitch. Risers must always be one size greater than the size of the connection size from the building. In NYC where the minimum size of a sewer connection is 6″ the size of a typical riser is 8″.
Who inspects house sewer riser connections in NYC?
When a riser must be built, they are carefully inspected by DEP field personnel. A new riser must conform to accepted DEP design standards. All risers must be encased with an approved ready-mix concrete, and also reinforced with re-bar, to provide a long-lasting connection. Interestingly, after the installation is signed off by the DEP the future maintenance and ownership of it reverts back to the NYC DEP.
All riser installations are built with a clean-out on the top as a way to clean out any possible future stoppages. If a riser has to be built it will add at least a few thousand dollars to the cost of an installation. Other than having to build a new manhole it is the most expensive connection to build.
6. New manhole connection
In rare instances a new NYC DEP approved manhole has to be built for connection to the city sewer. This is required typically for very large house sewer connections such as for a 12″ house sewer.
A manhole connection involves purchasing precast concrete rings from an approved vendor. The other components are a top slab with a ring and manhole cover. Using precast concrete lowers the total cost by eliminating form work , and the associated lumber and labor. All the steps involved in building a manhole are very closely monitored and inspected by NYC DEP field inspectors.
In terms of cost the manhole material alone costs in excess of $2,000.00 including delivery. Once other costs such a labor, ready mix concrete, and roadway restoration are factored in a manhole connection, it is by far the costliest means to connect to a city sewer. In some cases it is less expensive to install two smaller sized house sewers in order to avoid having to build a new manhole connection.
How can this information help you?
New house sewer connections can be a substantial part of the cost of a project. Being familiar with the different types of connections can be very useful when you require this type of work. Knowing the cost factor s of each connection type can be helpful in keeping costs down on your project.
With over 70 years of combined experience Paul R. Balkan and David Balkan possess a wealth of knowledge about NYC water main and sewer work. If you have a question or need additional information they welcome your inquiry. All inquiries are responded to promptly.
See if Balkan Sewer And water Main Service can help you today, contact us via our Sewer and Water information request form.