HomeMy WebLinkAboutWater Design Report_Rev2
February 3, 2022 Revised March 29, 2022
Revised September 6, 2022
Suffolk County Department of Health Services
Office of Wastewater Management
360 Yaphank Avenue, Suite 2C
Yaphank, NY 11980
Attn.: Adrian Casillas
Re: New 10” Domestic Water Service/RPZ Device
For Strong’s Yacht Center
5780 West Hills Road Mattituck, New York
SCTM#: 1000-106-6-10 & 13.4
Dear Mr. Casillas:
PW Grosser Consulting (PWGC) has been retained by Strong’s Yacht Center LLC to
design the reduced pressure backflow prevention device (RPZ) for the proposed water
main extension at the above referenced location. The purpose of the water main
extension is to service two proposed boat storage buildings to be constructed on the
south portion of the site. The site is currently improved with a residential dwelling and
office building that both utilize domestic drinking wells. The existing wells will remain to
be utilized for irrigation purposes and both structures will be connected to public water.
The proposed water main extension will be a 10” diameter tap off the existing 12” diameter
water main located along Naugles Road. The water main extension will be equipped with
a water meter and 10” - Febco LF860 RPZ device. A new fire hydrant is proposed at end
of the water main extension and there are no secondary RPZ devices proposed for the
office building and boat storage facilities. The farthest connection is approximately 2,000
ft from the existing water main in Naugles Road and PWGC has performed design
calculations to ensure that adequate pressure will be provided at this connection point.
The water supply system has been designed for a maximum fire flow of 1,500 GPM with
a total head loss of 29 PSI. See Table 1 below for a breakdown of the distribution system
design parameters.
Note: The calculations above utilize a pipe length of 2,000 ft to determine the head loss in the distribution
system
Lowest Distribution
System Static Pressure
(PSI)
Flow
(GPM)
Head Loss
(PSI)
Estimated Dist.
System
Residual
Pressure (PSI)
Service
Line Dia.
(In)
Head Loss in
Distribution
System (PSI)
Elevation
Head Loss
(PSI)
Head Loss in
Water Meter
(PSI)
Head Loss
in RPZ
(PSI)
Pressure
Downstream
@ Building
(PSI)
VELOCITY
(FT/S)
62.00 500 0.73 61.27 10.0 1.49 4.22 3.50 10.00 42.06 2.04
62.00 750 1.55 60.45 10.0 3.15 4.22 3.50 10.00 39.57 3.07
62.00 1,000 2.64 59.36 10.0 5.37 4.22 3.75 10.00 36.02 4.09
62.00 1,250 4.00 58.00 10.0 8.11 4.22 3.75 9.50 32.42 5.11
62.00 1,500 5.60 56.40 10.0 11.37 4.22 3.90 9.50 27.42 6.13
62.00 1,750 7.45 54.55 10.0 15.12 4.22 4.00 9.50 21.72 7.15
62.00 2,000 9.53 52.47 10.0 19.35 4.22 4.30 9.50 15.09 8.17
Table 1: 10" Water Main Service Flows and Pressures
PROPOSED SERVICE LINE SYSTEMDISTRIBUTION SYSTEM
The existing residential dwelling that will be connected to the proposed water main
extension will be serviced by a 2” diameter tap off of the 10” diameter water main
extension. The 2” water line connection will be located upstream of the onsite RPZ
assembly since residential properties do not require backflow protection. There is
approximately a 50-foot increase in elevation between the proposed 2” water service tap
and grade at the dwelling. The anticipated pressure provided at the building during
normal flow conditions will be a minimum of 35 psi. See Tables 2 and 3 below for a
breakdown of the distribution system design parameters.
Note: The calculations above utilize a pipe length of 730 ft to determine the head loss in the distribution system at the tee connection for the service line to the existing dwelling
Note: The calculations above utilize a pipe length of 630 ft to determine the head loss in the 2” water service
line for the existing dwelling
In compliance with the requirement of the New York State Health Department, Suffolk
County Department of Health Services and the Suffolk County Water Authority, one RPZ
is proposed for the water main extension that will service the boat storage buildings and
office building. The RPZ device will be located in the northeast corner of the property
and the RPZ device will be 10” – Febco Model LF860. At the peak demand of 1,500 GPM,
the head loss through the RPZ is 9.5 psi. The anticipated pressure downstream of the RPZ
will about approximately 27 psi during fire flow conditions and 44 psi during normal
conditions.
If you have any questions, please do not hesitate to call me.
Very truly yours,
P.W. Grosser Consulting Inc.
Bryan Grogan, P.E. Senior Vice President
Lowest Distribution
System Static Pressure
(PSI)
Flow
(GPM)
Head Loss
(PSI)
Estimated Dist.
System
Residual
Pressure (PSI)
Service Line
Dia. (In)
Head Loss in
Distribution
System (PSI)
Elevation
Head Loss
(PSI)
Pressure
Downstream @
Tee Connection
(PSI)
VELOCITY
(FT/S)
62.00 10 0.001 62.00 10.0 0.00 3.46 58.54 0.04
62.00 20 0.002 62.00 10.0 0.00 3.46 58.53 0.08
Table 2: 10" Water Main Service Flows and Pressures
Lowest Distribution
System Static Pressure
(PSI)
Flow
(GPM)
Head Loss
(PSI)
Estimated Dist.
System
Residual
Pressure (PSI)
Service Line
Dia. (In)
Head Loss in
Distribution
System (PSI)
Elevation Head
Loss (PSI)
Pressure
Downstream @
Dwelling (PSI)
VELOCITY
(FT/S)
58.54 10 0.001 58.54 2.0 0.85 20.24 37.45 1.02
58.53 20 0.002 58.53 2.0 3.06 20.24 35.23 2.04
Table 3: 2" Tap Service Flows and Pressures