"Worksheet for Determination of Safe Yield" - Connecticut

Worksheet for Determination of Safe Yield 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 DETERMINATION OF SAFE YIELD
Applicable Regulations:
RCSA Section 25-32d-1a (30): "Safe yield" means the maximum dependable quantity of water per unit of
time which may flow or be pumped continuously from a source of supply during a critical dry period
without consideration of available water limitations.
Background:
Water companies required to submit a water supply plan are required to evaluate the water supply needs
in their service area and propose a strategy to meet such needs. Part of this evaluation includes the
determination of the calculation of the safe yield of each source of supply in accordance with Section 25-
32d-4 of the Regulations of Connecticut State Agencies (RCSA). This application covers all of the
regulatory requirements required of these regulations for calculation of safe yield.
Applicability:
To be completed by public water systems supplied by surface water reservoirs or ground water wells.
Public water systems whose sources of supply are exclusively from one or more interconnections with
another water company(s) and do not have their own reservoir or well supplies do not need to complete
this application since the safe yield does not apply to an interconnection as a source of supply.
Instructions:
Provide the public water system (PWS) name, public water system identification number (PWSID), and
primary town the water system is located. For each source of supply, fill in the well or reservoir name and
the associated Water System Facility Identification (WSFID). The WSFID for each source of supply can
be obtained from the water quality monitoring schedules available on the Department’s website.
(http://www.ct.gov/dph/publicdrinkingwater). The regulatory sections and subsections are provided at the
heading of each section and regulatory divisions or subdivisions are provided along the right hand column
for reference.
Section A – Surface Water Sources (page 3):
Complete one worksheet for each surface water source. For each source of supply, fill in the reservoir
name and the associated WSFID. Check the box or boxes that correlate to the applicable regulation used
for calculation of safe yield. If a yield test was determined based on a system of surface water reservoirs
then list the name of the reservoir system and include the WSFID numbers for each reservoir that is part
of the reservoir system. Provide the final safe yield determined for the methodology used and report the
value in gallons per day. Include a copy of the Public Water System Application For Safe Yield for each
source of supply in the appropriate section of the water supply plan being submitted for review and
approval. Include all supporting documentation required of RCSA Section 25-32d-4(a)(11).
Section B – Ground Water Sources (pages 4-7):
Complete one worksheet for each groundwater source. For each source of supply, fill in the well name
and the associated WSFID. Check the box or boxes that correlate to the applicable regulation used for
calculation of safe yield. If a yield test was determined for multiple wells in a well field then list the
name of the well field and include the WSFID numbers for well in the well field. Provide the final safe
yield determined for the methodology used. Include a copy of the worksheet for determination of Safe
Yield for each source of supply in the appropriate section of the water supply plan being submitted for
review and approval. Include all supporting documentation required of RCSA Section 25-32d-4(b)(4).
Revised: 5/23/16
Page 1 of 10
STATE OF CONNECTICUT DEPARTMENT OF PUBLIC HEALTH
DRINKING WATER SECTION
WORKSHEET FOR DETERMINATION OF SAFE YIELD
Applicable Regulations:
RCSA Section 25-32d-1a (30): "Safe yield" means the maximum dependable quantity of water per unit of
time which may flow or be pumped continuously from a source of supply during a critical dry period
without consideration of available water limitations.
Background:
Water companies required to submit a water supply plan are required to evaluate the water supply needs
in their service area and propose a strategy to meet such needs. Part of this evaluation includes the
determination of the calculation of the safe yield of each source of supply in accordance with Section 25-
32d-4 of the Regulations of Connecticut State Agencies (RCSA). This application covers all of the
regulatory requirements required of these regulations for calculation of safe yield.
Applicability:
To be completed by public water systems supplied by surface water reservoirs or ground water wells.
Public water systems whose sources of supply are exclusively from one or more interconnections with
another water company(s) and do not have their own reservoir or well supplies do not need to complete
this application since the safe yield does not apply to an interconnection as a source of supply.
Instructions:
Provide the public water system (PWS) name, public water system identification number (PWSID), and
primary town the water system is located. For each source of supply, fill in the well or reservoir name and
the associated Water System Facility Identification (WSFID). The WSFID for each source of supply can
be obtained from the water quality monitoring schedules available on the Department’s website.
(http://www.ct.gov/dph/publicdrinkingwater). The regulatory sections and subsections are provided at the
heading of each section and regulatory divisions or subdivisions are provided along the right hand column
for reference.
Section A – Surface Water Sources (page 3):
Complete one worksheet for each surface water source. For each source of supply, fill in the reservoir
name and the associated WSFID. Check the box or boxes that correlate to the applicable regulation used
for calculation of safe yield. If a yield test was determined based on a system of surface water reservoirs
then list the name of the reservoir system and include the WSFID numbers for each reservoir that is part
of the reservoir system. Provide the final safe yield determined for the methodology used and report the
value in gallons per day. Include a copy of the Public Water System Application For Safe Yield for each
source of supply in the appropriate section of the water supply plan being submitted for review and
approval. Include all supporting documentation required of RCSA Section 25-32d-4(a)(11).
Section B – Ground Water Sources (pages 4-7):
Complete one worksheet for each groundwater source. For each source of supply, fill in the well name
and the associated WSFID. Check the box or boxes that correlate to the applicable regulation used for
calculation of safe yield. If a yield test was determined for multiple wells in a well field then list the
name of the well field and include the WSFID numbers for well in the well field. Provide the final safe
yield determined for the methodology used. Include a copy of the worksheet for determination of Safe
Yield for each source of supply in the appropriate section of the water supply plan being submitted for
review and approval. Include all supporting documentation required of RCSA Section 25-32d-4(b)(4).
Revised: 5/23/16
Page 1 of 10
Section C – Historical Records (page 8):
Complete one worksheet for each source of supply (surface water or ground water) if the determination of
safe yield for the source of supply was established based on available historical records. For each source
of supply, fill in the source of supply name and the associated WSFID. Check the box or boxes that
correlate to the applicable regulation used for calculation of safe yield. Provide the final safe yield
determined based on the historical data used and report the value in gallons per day. Include a copy of
the worksheet for determination of Safe Yield for each source of supply in the appropriate section of the
water supply plan being submitted for review and approval. Include all supporting documentation
required of RCSA Section 25-32d-4(c)(3).
Section D – Previously Approved Safe Yield (page 9):
Complete one worksheet for each source of supply (surface water or ground water) if the determination of
safe yield for the source of supply was established based on a previously approved safe yield. For each
source of supply, fill in the source of supply name and the associated WSFID. Check the box or boxes
that correlate to the applicable regulation used for calculation of safe yield. Provide the final safe yield
determined based on a previously approved safe yield and report the value in gallons per day. Include a
copy of the worksheet for determination of Safe Yield for each source of supply in the appropriate section
of the water supply plan being submitted for review and approval.
Section E – Other Approved Methods (page 10):
Complete one worksheet for each source of supply (surface water or ground water) if the determination of
safe yield for the source of supply was established based on other methods approved by the Department
of Public Health and Department of Energy and Environmental Protection. For each source of supply, fill
in the source of supply name and the associated WSFID. Check the box or boxes that correlate to the
applicable regulation used for calculation of safe yield. Provide the final safe yield determined based on
the other approved method used and report the value in gallons per day. Include a copy of the worksheet
for determination of Safe Yield for each source of supply in the appropriate section of the water supply
plan being submitted for review and approval. Provide documentation that both the Department of
Public Health and Department of Energy and Environmental Protection approved the method being used
for calculation of safe yield. Also provide the supporting data that was used to calculate the safe yield.
Certification
The public water system owner or administrative contact is requested to sign, date and print their name
certifying the information submitted for safe yield is accurate to the best of their knowledge and was
determined in accordance with the applicable Regulations of Connecticut State Agencies.
Revised: 5/23/16
Page 2 of 10
CALCULATION OF SAFE YIELD
Date:
PWS Name:
PWSID:
Town:
A
SURFACE WATER SOURCES
RCSA Section 25-32d-4(a)
Calculation of Safe Yield for Surface Water Sources
☐ 1. The surface water safe yield analyses was performed by an individual with a minimum of five
years experience in surface water analysis and a bachelor's or advanced degree from an
accredited college or university in hydrology or related engineering field, or by a professional
engineer licensed in accordance with Chapter 391 of the Connecticut General Statutes with a
minimum of five years experience in surface water analysis.
Name of individual performing yield test: ___________________________________________
☐ Degree: __________________________________________________________________
(a)
Years of experience in surface water analysis: ____________________________________
Accredited college or University: ______________________________________________
☐ Professional engineer licensed in accordance with Chapter 391 of the Connecticut General
Statutes.
P.E. License number: _______________________________________________________
Years of experience in surface water analysis: ____________________________________
☐ 2. Safe yield shall was calculated using a mathematical mass balance methodology and was based
on a ninety-nine percent dry year or a critical dry period with a 1 in 100 occurrence frequency
and was based on the usable storage capacity of a reservoir which can be used without
(a)
additional equipment or treatment, except that the safe yield may be less due to requirements for
the passing of minimum stream flows or other release requirements.
☐ 3. Safe yield was determined based upon an analysis of the stream flow for a ninety nine percent
dry year assuming a seven day average flow duration since a mass balance analysis cannot be
(a)
performed due to insufficient usable storage volume. (i.e.: a run of the river type situation or
diversions)
WSFID
Source of Supply Name
Safe Yield (GPD):
Revised: 5/23/2016
Page 3 of 10
CALCULATION OF SAFE YIELD
Date:
PWS Name:
PWSID:
Town:
B
GROUND WATER SOURCES
RCSA Section 25-32d-4(b)
Safe yield of all active wells shall be computed based upon simultaneous pumping tests of all wells
in the well field and adjusted for the maximum drawdown available during a critical dry period.
1. The ground water safe yield analyses was performed by an individual with a minimum of five
years experience in ground water analysis in a glaciated geomorphological setting and a bachelor's
or advanced degree from an accredited college or university in a ground water related science or
related engineering field, or by a professional engineer licensed in accordance with Chapter 391 of
the Connecticut General Statutes with a minimum of five years experience in ground water
analysis in a glaciated geomorphological setting.
Name of individual performing yield test: ___________________________________________
(b)
☐ Degree: __________________________________________________________________
Years of experience in ground water analysis: ____________________________________
Accredited college or University: ______________________________________________
☐ Professional engineer licensed in accordance with Chapter 391 of the Connecticut General
Statutes.
P.E. License number: _______________________________________________________
Years of experience in ground water analysis: ____________________________________
RCSA Section 25-32d-4(b)(1)
2. The standard method of adjusting pump test data to account for critical dry period was used.
(If the standard method was used to adjust pump test data applies, also complete either #3 or #4 below)
3. The safe yield was computed based on a standard method of adjusting pumping test data to
account for the critical dry period was based on one of the following:
☐ For all ground water sources, a multiplier of seventy-five percent, equivalent to an eighteen
hour pumping day, was applied to the pumping test rate. This adjustment factor was
applied for calculating and making adjustments for the critical dry period. The resulting
safe yield was reported in units of both gallons per minute, and gallons per day.
(A)
☐ In addition to the critical dry period adjustment factor, an additional multiplier of ninety
percent was applied to bedrock or consolidated aquifer ground water sources.
Date(s) the pump test was conducted:______________________________________________
4. The safe yield was computed based on pumping test data that was analyzed and adjusted for the
critical dry period using methodologies appropriate to the hydrogeologic setting and published
*
methodologies as approved by the department
.
Date(s) the pump test was conducted:______________________________________________
*
Include a copy of the correspondence from the Department with approval of the published
(B)
methodology appropriate to the hydrogeologic setting. Analytical methods used in this
section shall account for all criteria in RCSA Section 25-32d-4(b)(1)(B)(i) through 25-32d-
4(b)(1)(B)(v). Please note that previous approval of a water supply plan where safe yield
was calculated using a published methodology does not in itself qualify as Department
approval of the methodology.
Revised: 5/23/2016
Page 4 of 10
RCSA Section 25-32d-4(b)(2)
5. An alternative method for analyzing pumping test data was completed at the water company's option
because stabilized water levels were above the pump intake or water levels did not stabilize and
predicted water levels are above the pump intake after an extrapolation of drawdown over 180 days
of pumping.
6. The alternative method that was used to indicate the additional yield of the well above the installed
(b)(2)
pumping capacity at the time of the pumping test showed:
☐ a) Stabilization occurred above the pump intake.
☐ b) Stabilization did not occur; however the pump test shows that the aquifer has sufficient
storage to sustain pumping at the higher rate during the critical dry period and is intended
to indicate the maximum well yield attainable with pump replacement, modification, or
increased capacity.
☐ c) The alternative method used conforms to analytical methodologies or modeling techniques
(A)
appropriate to the hydrogeological setting and published methodologies as approved by the
*
department
to predict water levels at the higher pumping rate.
☐ d) The analysis technique took into account mutual interference effects on all wells located in
(B)
the same well field.
☐ e) Corrections for the critical dry period were performed in accordance with Section 25-32d-
(C)
4(b)(1)(A) or Section 25-32d-4(b)(1)(B) of the Regulations of Connecticut State Agencies.
*
Include a copy of the correspondence from the Department with approval of the published
methodology appropriate to the hydrogeologic setting. Please note that previous approval of
a water supply plan where safe yield was calculated using a published methodology does not
in itself qualify as Department approval of the methodology.
RCSA Section 25-32d-4(b)(3)
A well field pumping test used to determine safe yield shall satisfy the following criteria:
Note: All criteria in this section are applicable to the standard method [RCSA Section 25-32d-4(b)(1)] and the
alternative method [RCSA Section 25-32d-4(b)(2)]for establishing a safe yield unless variation(s) are used per
RCSA Section 25-32d-4(b)(3)(K).
7. A pumping test was conducted with all wells in the well field pumping simultaneously to
determine time-drawdown characteristics of the pumped wells.
(A)
☐ 8. The rate of pumping of all wells was constant throughout the pumping test.
(A)
☐ 9. Each well was individually metered during the pump test.
(A)
10. The well field has more than one well and existing data from individual, non-simultaneous
pumping tests of each well in the well field that meet the other pumping test requirements were
(A)
utilized, provided corrections were made for mutual interference.
11. The pumping test was conducted for at least the minimum duration required in Section 19-13-
(B)
B51k of the Regulations of Connecticut State Agencies.
12. The water level in the well(s) stabilized for the last twelve hours prior to completion of the
(C)
pumping test.
13. Stabilization was not achieved after the required pumping test duration therefore the pumping test
(C)
was extended.
14. Stabilization was not achieved after the required pumping test duration therefore an analysis and
extrapolation of pumping test drawdown versus time data was performed to show whether there is
sufficient storage in the aquifer to sustain the pumping rate for 180 days of continual operation and
(C)
maintain water levels above the pump intake.
☐ The 180 day projection shows the water level would be above the pump intake.
Page 5 of 10
Revised: 5/23/2016
Page of 10