"Worksheet for Demonstration of Margin of Safety (Mos)" - Connecticut

Worksheet for Demonstration of Margin of Safety (Mos) is a legal document that was released by the Connecticut State Department of Public Health - a government authority operating within Connecticut.

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STATE OF CONNECTICUT DEPARTMENT OF PUBLIC HEALTH
DRINKING WATER SECTION
WORKSHEET FOR DEMONSTRATION OF MARGIN OF SAFETY (MOS)
Applicable Regulations:
Regulations of Connecticut State Agencies (RCSA) Section 25-32d-1a (a)(2): ‘‘Active source’’ means a
department approved source of supply which meets state and federal water quality standards, with adequate
department approved treatment facilities as needed, or for which compliance schedules are in place. An active
source is one that is permanently connected to the system and may include, but need not be limited to, a seasonal
or standby source of supply that may be used intermittently or on a partial year basis;
RCSA Section 25-32d-1a (a)(4): “Available water” means the maximum amount of water a company can
dependably supply, taking into account the following reductions applied to safe yield: any limitations imposed by
hydraulics, treatment, well pump capabilities, reductions of well yield due to clogging that can be corrected with
redevelopment, transmission mains, permit conditions, source construction limitations, approval limitations, or
operational considerations; and the safe yield of active sources and water supplied according to contract, provided
that the contract is not subject to cancellation or suspension and assures the availability of water throughout a
period of drought and that the supply is reliable.
RCSA Section 25-32d-1a (a)(5): ‘‘Average daily demand (ADD)’’ means the total annual production from all
sources of supply divided by the number of days in that calendar year;
RCSA Section 25-32d-1a (a)(22): ‘‘Margin of safety (MOS)’’ means the unitless ratio of available water to
demand;
RCSA Section 25-32d-1a (a)(24): ‘‘Maximum month demand (MMD)’’ means the highest water demand in a
month calculated by dividing the total production from all sources of supply for each calendar month by the
number of days in that month and expressed in gallons per day;
RCSA Section 25-32d-1a (a)(28): ‘‘Peak day demand (PDD)’’ means the annual maximum daily rate of water use
measured in gallons per day;
Background:
Water companies required to submit a water supply plan are required to provide an analysis of the relationship
between available water and average daily demand as determined for the most recent representative period of
record not affected by unusual demand conditions such as drought or a significant temporary increase in demand,
maximum month demand and peak day demand and the margin of safety to be maintained by the water company
currently and for the five, twenty, and fifty year planning periods; and a demonstration that the margin of safety is
sufficient to meet the water company’s current and future needs considering factors such as potential increases or
decreases in demand, the time required to bring new sources of supply on line, potential losses of sources of
supply or decreased capacities, land area available for development, available interconnections and other factors
which may increase or reduce supply or demand per RCSA Sections 25-32d-3(b)(7) & (8). This worksheet will
help the public water system calculate the margin of safety for the five, ten, twenty and fifty year planning
periods. It is important that accurate and up to date safe yield data and accurate accounting of all system
limitations are used to allow for proper planning of new sources to ensure a continuous pure and adequate supply
to customers.
Instructions:
Provide the public water system (PWS) name, public water system identification number (PWSID), and primary
town the water system is located. In the first column, inactive and emergency sources of supply must not be
included since available water calculations only account for active sources of supply that meet the definition of
RCSA Section 25-32d-1a(2). In the second column; Average Day Demand (ADD), Maximum Month Demand
(MMD) and Peak Day Demand (PDD) should be expressed in gallons per day (GPD), and the Margin of Safety
(MOS) for each type of water demand is calculated as a unitless ratio of available water to water demand.
The public water system owner or administrative contact is requested to sign, date and print their name certifying
the information submitted for demonstration of margin of safety (MOS) is accurate to the best of their knowledge
and was determined in accordance with the applicable Regulations of Connecticut State Agencies.
DPH DWS Worksheet for Demonstration of Margin of Safety (Revised 5/23/16)
STATE OF CONNECTICUT DEPARTMENT OF PUBLIC HEALTH
DRINKING WATER SECTION
WORKSHEET FOR DEMONSTRATION OF MARGIN OF SAFETY (MOS)
Applicable Regulations:
Regulations of Connecticut State Agencies (RCSA) Section 25-32d-1a (a)(2): ‘‘Active source’’ means a
department approved source of supply which meets state and federal water quality standards, with adequate
department approved treatment facilities as needed, or for which compliance schedules are in place. An active
source is one that is permanently connected to the system and may include, but need not be limited to, a seasonal
or standby source of supply that may be used intermittently or on a partial year basis;
RCSA Section 25-32d-1a (a)(4): “Available water” means the maximum amount of water a company can
dependably supply, taking into account the following reductions applied to safe yield: any limitations imposed by
hydraulics, treatment, well pump capabilities, reductions of well yield due to clogging that can be corrected with
redevelopment, transmission mains, permit conditions, source construction limitations, approval limitations, or
operational considerations; and the safe yield of active sources and water supplied according to contract, provided
that the contract is not subject to cancellation or suspension and assures the availability of water throughout a
period of drought and that the supply is reliable.
RCSA Section 25-32d-1a (a)(5): ‘‘Average daily demand (ADD)’’ means the total annual production from all
sources of supply divided by the number of days in that calendar year;
RCSA Section 25-32d-1a (a)(22): ‘‘Margin of safety (MOS)’’ means the unitless ratio of available water to
demand;
RCSA Section 25-32d-1a (a)(24): ‘‘Maximum month demand (MMD)’’ means the highest water demand in a
month calculated by dividing the total production from all sources of supply for each calendar month by the
number of days in that month and expressed in gallons per day;
RCSA Section 25-32d-1a (a)(28): ‘‘Peak day demand (PDD)’’ means the annual maximum daily rate of water use
measured in gallons per day;
Background:
Water companies required to submit a water supply plan are required to provide an analysis of the relationship
between available water and average daily demand as determined for the most recent representative period of
record not affected by unusual demand conditions such as drought or a significant temporary increase in demand,
maximum month demand and peak day demand and the margin of safety to be maintained by the water company
currently and for the five, twenty, and fifty year planning periods; and a demonstration that the margin of safety is
sufficient to meet the water company’s current and future needs considering factors such as potential increases or
decreases in demand, the time required to bring new sources of supply on line, potential losses of sources of
supply or decreased capacities, land area available for development, available interconnections and other factors
which may increase or reduce supply or demand per RCSA Sections 25-32d-3(b)(7) & (8). This worksheet will
help the public water system calculate the margin of safety for the five, ten, twenty and fifty year planning
periods. It is important that accurate and up to date safe yield data and accurate accounting of all system
limitations are used to allow for proper planning of new sources to ensure a continuous pure and adequate supply
to customers.
Instructions:
Provide the public water system (PWS) name, public water system identification number (PWSID), and primary
town the water system is located. In the first column, inactive and emergency sources of supply must not be
included since available water calculations only account for active sources of supply that meet the definition of
RCSA Section 25-32d-1a(2). In the second column; Average Day Demand (ADD), Maximum Month Demand
(MMD) and Peak Day Demand (PDD) should be expressed in gallons per day (GPD), and the Margin of Safety
(MOS) for each type of water demand is calculated as a unitless ratio of available water to water demand.
The public water system owner or administrative contact is requested to sign, date and print their name certifying
the information submitted for demonstration of margin of safety (MOS) is accurate to the best of their knowledge
and was determined in accordance with the applicable Regulations of Connecticut State Agencies.
DPH DWS Worksheet for Demonstration of Margin of Safety (Revised 5/23/16)
STATE OF CONNECTICUT DEPARTMENT OF PUBLIC HEALTH
DRINKING WATER SECTION
WORKSHEET FOR DEMONSTRATION OF MARGIN OF SAFETY (MOS)
Public Water System Name:
_________________________________________________________
PWSID:
_________________________________________________________
Town(s):
_________________________________________________________
Available Water of all Active Sources & Interconnections
(GPD)
Water Demand Based on Past 5 Years
Based on Worksheet for Demonstration of Available Water
ADD
MOS
MMD
MOS
PDD
MOS
Available Water of all Active Sources & Interconnections
(GPD)
Water Demand Projected for the next 5 Years
Based on Worksheet for Demonstration of Available Water
ADD
MOS
MMD
MOS
PDD
MOS
Available Water of all Active Sources & Interconnections
(GPD)
Water Demand Projected for the next 10 Years
Based on Worksheet for Demonstration of Available Water
ADD
MOS
MMD
MOS
PDD
MOS
DPH DWS Worksheet for Demonstration of Margin of Safety (Revised 5/23/2016)
Page 1 of 2
Available Water of all Active Sources & Interconnections
(GPD)
Water Demand Projected for the next 20 Years
Based on Worksheet for Demonstration of Available Water
ADD
MOS
MMD
MOS
PDD
MOS
Available Water of all Active Sources & Interconnections
(GPD)
Water Demand Projected for the next 50 Years
Based on Worksheet for Demonstration of Available Water
ADD
MOS
MMD
MOS
PDD
MOS
My signature below certifies that the information provided on this worksheet for demonstration of margin of safety (MOS) for the public water system
indicated is accurate to the best of my knowledge and complies with the applicable Regulations of Connecticut State Agencies.
________________________________________________ __
____________________
(Signature of public water system Owner or Administrative contact)
(Date)
_________________________________________________
(Print or type name)
DPH DWS Worksheet for Demonstration of Margin of Safety (Revised 5/23/2016)
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