Education Facility Impact Fee Study

Prepared for:

Williamson County, Tennessee
September 20, 2019

4701 Sangamore Road, Suite S240
Bethesda, MD
301.320.6900
www.tischlerbise.com

 Education Facility Impact Fee Report

Williamson County, Tennessee

TABLE OF CONTENTS
EXECUTIVE SUMMARY .................................................................................................... 1
IMPACT FEE METHODOLOGIES ..................................................................................................... 1
Rounding ................................................................................................................................ 2
CURRENT EDUCATION FACILITY IMPACT FEES .............................................................................. 2
Figure 1: Current Education Facility Impact Fees............................................................................................... 3

MAXIMUM SUPPORTABLE EDUCATION FACILITY IMPACT FEES ....................................................... 3
Figure 2: Proposed Development Fees .............................................................................................................. 4

OVERVIEW OF IMPACT FEES .......................................................................................... 5
LEGAL FRAMEWORK .................................................................................................................... 5
REQUIRED FINDINGS ................................................................................................................... 5
METHODOLOGIES AND CREDITS ................................................................................................... 6
WILLIAMSON COUNTY EDUCATION FACILITY IMPACT FEE OVERVIEW ..................... 8
ENROLLMENT PROJECTIONS AND STUDENT GENERATION RATES .......................... 9
ENROLLMENT PROJECTIONS ......................................................................................................... 9
Figure 3: Enrollment Projections......................................................................................................................... 9

STUDENT GENERATION RATES .................................................................................................... 9
Student Generation Rates by Unit Size ................................................................................. 9
Figure 4: School Age Children by Bedroom Count ........................................................................................... 10
Figure 5: Student Generation Rates by Bedroom Count .................................................................................. 11
Figure 6: Student Generation Rates for Grades K-8 by Unit Size .................................................................... 12
Figure 7: Student Generation Rates for Grades K-8 by Unit Size .................................................................... 13
Figure 8: Student Generation Rates by Unit Size ............................................................................................. 14

EDUCATION FACILITY IMPACT FEES: WILLIAMSON COUNTY SCHOOLS ................. 15
METHODOLOGY ......................................................................................................................... 15
Figure 9. Impact Fee Methodology Chart ......................................................................................................... 16

BUILDING LEVEL-OF-SERVICE STANDARDS................................................................................. 16
WCS Elementary and Middle Schools (K-8) ........................................................................ 16
Figure 10. Elementary and Middle Schools Level-of-Service Standards (K-8)................................................. 17

WCS High Schools ............................................................................................................... 18
Figure 11. High Schools Level-of-Service Standards ....................................................................................... 18

LAND ACQUISITION COSTS......................................................................................................... 18
Figure 12. Land Acquisition Costs .................................................................................................................... 19

SCHOOL CONSTRUCTION COSTS ............................................................................................... 19
Figure 13. School Project Costs ....................................................................................................................... 19

SUPPORT FACILITIES LEVEL-OF-SERVICE AND COSTS ................................................................ 19
Figure 14. Support Facilities Level-of-Service and Costs ................................................................................. 20

BUS LEVEL-OF-SERVICE AND COSTS .................................................................................... 20
Figure 15. Buses Level-of-Service and Costs .................................................................................................. 20

CREDIT FOR OFFSETTING REVENUES......................................................................................... 21
Figure 16. Credit for Offsetting Revenues ........................................................................................................ 22

MAXIMUM SUPPORTABLE EDUCATION FACILITY IMPACT FEES FOR WCS ..................................... 22

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Figure 17. Education Facility Impact Fee Input Variables ................................................................................ 23
Figure 18. Maximum Supportable Education Facility Impact Fees: WCS ........................................................ 24
Figure 19. WCS Maximum Supportable Education Facility Impact Fees within FSSD .................................... 25

IMPLEMENTATION AND ADMINISTRATION .................................................................. 26
ACCOUNTING ............................................................................................................................ 26
SITE-SPECIFIC CREDITS ............................................................................................................ 26
COLLECTION AND EXPENDITURE ZONES ..................................................................................... 26

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EXECUTIVE SUMMARY
TischlerBise was retained by Williamson County, Tennessee, to calculate impact fees for public schools to
meet the demands generated by new residential development for school facilities in the County. The
County has been granted authority by the State to implement impact fees for school facilities by private
act of the Tennessee General Assembly. Education facility impact fees were adopted under Resolution 1116-6, Section 10, which mandates the fees be updated every three years.
Impact fees are one-time payments used to defray the cost impacts of school facilities necessary to
accommodate new development. The payment amount represents new growth’s fair share of capital
facility needs. TischlerBise evaluated possible methodologies and documented appropriate demand
indicators by type of development for the fee amounts. Specific capital costs have been identified using
local data and current dollars. Level-of-service (LOS) standards and cost factors are presented in this
report and are the basis for the calculations. It should be noted that although growth affects both capital
and operating expenses incurred by schools, the impact fee analysis addresses new development’s impact
on capital facilities only. It is further limited to capital improvements that provide additional capacity as
opposed to maintenance or rehabilitation.
Williamson County is served by two school systems, Williamson County Schools (WCS) and the Franklin
Special School District (FSSD). Students living in FSSD attend these schools from kindergarten to eighth
grade, after which they attend WCS high schools. This report details only impact fees for WCS. New
residential construction located in FSSD will be charged for only the high school component of the WCS
impact fee, since students generated from these homes will only attend William County Schools for high
school.

IMPACT FEE METHODOLOGIES
There are three basic methodologies used to calculate impact fees. The incremental expansion method
documents the current levels-of-service for each type of public facility in both quantitative and qualitative
measures. The intent is to use fee revenue to expand or provide additional facilities, as needed to
accommodate new development, based on the current cost to provide capital improvements. The planbased method is commonly used for public facilities that have adopted plans or engineering studies to
guide capital improvements, such as utility systems. A third approach, known as the cost recovery
method, is based on the rationale that new development is paying for its share of the useful life and
remaining unused capacity of an existing facility or land.
Maximum supportable education facility impact fees for Williamson County Schools are derived using the
incremental expansion approach. For school capital improvements, the most common methodology
employed is typically the incremental expansion method when future capacity needs are anticipated. This
approach allows for the greatest flexibility in providing future capacity improvements. Under this
methodology, the fees are based on current levels-of-service and costs for each type of school facility (i.e.,
grades K-8 and grades 9-12), land, support facilities, and buses. The level-of-service is documented, and
the intent is to use fee revenue to provide additional or expanded public school and related facilities as
needed to accommodate new development.

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 Education Facility Impact Fee Report

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The current level-of-service and capital costs for new or expanded facilities are used to derive a cost per
student for each type of school facility. Using the cost per student and the average Williamson County
Schools student generation rate by size of unit, a cost per residential unit is derived. The term “student
generation rate” refers to the average number of public school students per housing unit in the Williamson
County School system. Further discussion on student generation rate calculations is provided in the body
of this report and in Appendix A.
A general requirement common to impact fee calculations is the evaluation of credits. Two types of credits
should be considered, credits for offsetting revenue and site-specific credits. Credits for offsetting
revenue are necessary to avoid potential double payment situations arising from the payment of a onetime impact fee plus the payment of other revenues (e.g., Adequate School Facility Privilege Tax) that may
also fund growth-related capital improvements. Credits for offsetting revenue are dependent upon the
fee methodology used in the cost analysis. To avoid this potential double payment situation, credits for
offsetting revenue are integrated into the impact fee methodology to account for privilege tax revenue
used to retire outstanding debt on Williamson County School facilities. A credit is necessary since new
residential units that will pay the education facility impact fee will also contribute one-time Adequate
School Facility Privilege Tax and Adequate Facilities Privilege Tax revenue used by Williamson County to
fund school capacity.
The second type of credit, a site-specific credit, is for school-related land or facilities that have been
included in the education facility impact fee calculations. Policies and procedures related to site-specific
credits for system improvements should be addressed in the resolution that establishes the County’s
education facility impact fees. However, the general concept is that developers may be eligible for sitespecific credits or reimbursements only if they provide land or construct school improvements that have
been included in the education facility impact fee calculations.

Rounding
A note on rounding: calculations throughout this report are based on an analysis conducted using Excel
software. Most results are discussed in the report using two, three, and four-digit places, which represent
rounded figures. However, the analysis itself uses figures carried to their ultimate decimal places;
therefore, the sums and products generated in the analysis may not equal the sum or product if the reader
replicates the calculation with the factors shown in the report (due to the rounding of figures shown, not
in the analysis).

CURRENT EDUCATION FACILITY IMPACT FEES
The County’s current education facility impact fees are shown below in Figure 1. Fees for grade K-12 are
assessed in all areas of the County outside the Franklin Special School District. Within the Franklin Special
School District, fees are only assessed at the high school level, as the Franklin Special School District
provides elementary and middle school space.

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Figure 1: Current Education Facility Impact Fees
MAXIMUM ALLOWABLE SCHOOL IMPACT FEES: Williamson Co. Schools
(outside Franklin Special School District boundaries)
Impact Fee per Housing Unit*
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

School Level
K-12
$2,827
$5,317
$7,220
$8,788
$10,074
$11,210

MAXIMUM ALLOWABLE SCHOOL IMPACT FEES: Williamson Co. Schools
(inside Franklin Special School District boundaries)
Impact Fee per Housing Unit*
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

School Level
9-12
$1,145
$1,914
$2,502
$2,993
$3,386
$3,745

*Fees do not apply to age-restricted units

MAXIMUM SUPPORTABLE EDUCATION FACILITY IMPACT FEES
Education facility impact fees are applied only to residential development and are calculated per housing
unit, reflecting the proportionate demand by type of unit. The amounts shown are “maximum
supportable” amounts based on the methodologies, level-of-service standards, and costs for the school
capital improvements identified herein. The fees represent the highest amount feasible for each type of
applicable development, which represent new growth’s fair share of the education facility capital costs as
detailed in this report. The County can adopt amounts that are lower than the maximum amounts shown.
However, a reduction in fee revenue will necessitate an increase in other revenues, a decrease in planned
capital expenditures, and/or a decrease in level-of-service.
The top of Figure 2 provides the schedule of maximum supportable education facility impact fees for
residential units outside of the Franklin Special School District. The bottom section of Figure 2 summarizes
the maximum supportable education facility impact fee within the Franklin Special School District.
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Figure 2: Proposed Development Fees
MAXIMUM ALLOWABLE EDUCATION FACILITY IMPACT FEES: Williamson Co. Schools
(outside Franklin Special School District boundaries)
Impact Fee per Housing Unit*
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

School Level
K-12

Current
Fees

$3,375
$6,021
$8,038
$9,685
$11,053
$12,244

$2,827
$5,317
$7,220
$8,788
$10,074
$11,210

Difference
$548
$704
$818
$897
$979
$1,034

MAXIMUM ALLOWABLE EDUCATION FACILITY IMPACT FEES: Williamson Co. Schools
(inside Franklin Special School District boundaries)
Impact Fee per Housing Unit*
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

School Level
9-12

Current
Fees

$1,105
$2,114
$2,895
$3,523
$4,057
$4,514

$1,145
$1,914
$2,502
$2,993
$3,386
$3,745

Difference
($40)
$200
$393
$530
$671
$769

*Fees do not apply to age-restricted units

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 Education Facility Impact Fee Report

Williamson County, Tennessee

OVERVIEW OF IMPACT FEES
Impact fees are one-time payments used to fund capital improvements necessitated by new growth. This
type of fee has been utilized by local governments in various forms for at least 50 years. Impact fees have
limitations and should not be regarded as the total solution for infrastructure financing needs. Rather,
they should be considered one component of a comprehensive portfolio to ensure adequate provision of
public facilities with the goal of maintaining current levels-of-service in a community in the face of new
growth.

LEGAL FRAMEWORK
U.S. Constitution. Like all land use regulations, development exactions—including impact fees—are
subject to the Fifth Amendment prohibition on taking of private property for public use without just
compensation. Both state and federal courts have recognized the imposition of impact fees on
development as a legitimate form of land use regulation, provided the fees meet standards intended to
protect against regulatory takings. To comply with the Fifth Amendment, development regulations must
be shown to substantially advance a legitimate governmental interest. In the case of impact fees, that
interest is the protection of public health, safety, and welfare by ensuring that development is not
detrimental to the quality of essential public services.
There is little federal case law specifically dealing with impact fees, although other rulings on other types
of exactions (e.g., land dedication requirements) are relevant. In one of the most important exaction
cases, the U. S. Supreme Court found that a government agency imposing exactions on development must
demonstrate an “essential nexus” between the exaction and the interest being protected (see Nollan v.
California Coastal Commission, 1987). In a more recent case (Dolan v. City of Tigard, OR, 1994), the Court
ruled that an exaction also must be “roughly proportional” to the burden created by development.
However, the Dolan decision appeared to set a higher standard of review for mandatory dedications of
land than for monetary exactions such as impact fees.

REQUIRED FINDINGS
There are three reasonable relationship requirements for impact fees that are closely related to “rational
nexus” or “reasonable relationship” requirements enunciated by a number of state courts. Although the
term “dual rational nexus” is often used to characterize the standard by which courts evaluate the validity
of impact fees under the U.S. Constitution, we prefer a more rigorous formulation that recognizes three
elements: “impact or need,” “benefit,” and “proportionality.” The dual rational nexus test explicitly
addresses only the first two, although proportionality is reasonably implied, and was specifically
mentioned by the U.S. Supreme Court in the Dolan case. The reasonable relationship language of the
statute is considered less strict than the rational nexus standard used by many courts. Individual elements
of the nexus standard are discussed further in the following paragraphs.
Demonstrating an Impact. All new development in a community creates additional demands on
some, or all, public facilities provided by local government. If the supply of facilities is not increased
to satisfy that additional demand, the quality or availability of public services for the entire
community will deteriorate. Impact fees may be used to recover the cost of development-related
facilities, but only to the extent that the need for facilities is a consequence of development that is
subject to the fees. The Nollan decision reinforced the principle that development exactions may be
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 Education Facility Impact Fee Report

Williamson County, Tennessee

used only to mitigate conditions created by the developments upon which they are imposed. That
principle clearly applies to impact fees. In this study, the impact of development on improvement
needs is analyzed in terms of quantifiable relationships between various types of development and
the demand for specific facilities, based on applicable level-of-service standards.
Demonstrating a Benefit. A sufficient benefit relationship requires that fee revenues be segregated
from other funds and expended only on the facilities for which the fees were charged. Fees must be
expended in a timely manner and the facilities funded by the fees must serve the development paying
the fees. Procedures for the earmarking and expenditure of fee revenues are typically mandated by
the State enabling act, as are procedures to ensure that the fees are expended expeditiously or
refunded. All of these requirements are intended to ensure that developments benefit from the fees
they are required to pay. Thus, an adequate showing of benefit must address procedural as well as
substantive issues.
Demonstrating Proportionality. The requirement that exactions be proportional to the impacts of
development was clearly stated by the U.S. Supreme Court in the Dolan case (although the relevance
of that decision to impact fees has been debated) and is logically necessary to establish a proper
nexus. Proportionality is established through the procedures used to identify development-related
facility costs, and in the methods used to calculate impact fees for various types of facilities and
categories of development. The demand for facilities is measured in terms of relevant and
measurable attributes of development. For example, the need for school improvements is measured
by the number of public school-age children generated by development.

METHODOLOGIES AND CREDITS
Any one of several legitimate methods may be used to calculate impact fees. The choice of a particular
method depends primarily on the service characteristics and planning requirements for the facility type
being addressed. Each method has advantages and disadvantages in a particular situation, and to some
extent can be interchangeable, because each allocates facility costs in proportion to the needs created by
development.
Reduced to its simplest terms, the process of calculating impact fees involves two main steps: (1)
determining the cost of development-related capital improvements and (2) allocating those costs
equitably to various types of development. In practice, though, the calculation of impact fees can become
quite complicated because of the many variables involved in defining the relationship between
development and the need for facilities. The following paragraphs discuss three basic methods for
calculating impact fees and how those methods can be applied.
Plan-Based Fee Calculation. The plan-based method allocates costs for a specified set of improvements
to a specified amount of development. The improvements are identified by a facility plan and
development is identified by a land use plan. In this method, the total cost of relevant facilities is divided
by total demand to calculate a cost per unit of demand. Then, the cost per unit of demand is multiplied
by the amount of demand per unit of development (e.g. housing units or square feet of building area) in
each category to arrive at a cost per specific unit of development (e.g., single family detached unit).

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Cost Recovery Fee Calculation. The rationale for the cost recovery approach is that new development is
paying for its share of the useful life and remaining capacity of facilities already built or land already
purchased from which new growth will benefit. To calculate a fee using the cost recovery approach, the
facility cost is divided by ultimate number of demand units (e.g., students) the facility will serve.
Incremental Expansion Fee Calculation. The incremental expansion method documents the current levelof-service for school facilities in both quantitative and qualitative measures, based on an existing service
standard (such as square feet per student). The level-of-service standards are determined in a manner
similar to the current replacement cost approach used by property insurance companies. However, in
contrast to insurance practices, the fee revenues would not be for renewal and/or replacement of existing
facilities. Rather, revenue will be used to expand or provide additional facilities, as needed, to
accommodate new development. An incremental expansion cost method is best suited for public facilities
that will be expanded in regular increments, with level-of-service standards based on current conditions
in the community.
Credits. Regardless of the methodology, a consideration of “credits” is integral to the development of a
legally valid impact fee methodology. There are two types of “credits” each with specific, distinct
characteristics, but both of which should be addressed in the calculation of impact fees. The first is a credit
due to possible double payment situations. This could occur when contributions are made by the property
owner toward the capital costs of the public facility covered by the impact fee. This type of credit is
integrated into the impact fee calculation. The second is a credit toward the payment of a fee for
dedication of public sites or improvements provided by the developer and for which the impact fee is
imposed. This type of credit is addressed in the administration and implementation of an impact fee
program.

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 Education Facility Impact Fee Report

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WILLIAMSON COUNTY EDUCATION FACILITY IMPACT FEE OVERVIEW
The County has seen significant residential growth over the past several years and with it increased
enrollment. Growth is expected to continue in the future, as shown below in the enrollment projections
(Figure 6). To ensure that Williamson County Schools have adequate capacity to accommodate growth,
Williamson County implemented impact fees for schools. The County has been granted authority by the
State to implement impact fees for schools by Private Act of the Tennessee General Assembly.
Williamson County is served by two school systems, Williamson County Schools (WCS) and Franklin Special
School District (FSSD). Students living in FSSD attend FSSD schools from kindergarten to eighth grade, after
which they attend WCS high schools. This report details only impact fees for WCS. New residential
construction located in FSSD will be charged for only the high school component of the WCS impact fee,
since students generated from these homes will only attend WCS for high school.
Williamson County education facility impact fees are derived using the incremental expansion approach.
This approach determines current level-of-service standards for school buildings (elementary and middle
schools and high schools), land, support facilities, and buses. Level-of-service standards are expressed as
follows:
§

School buildings: Square feet per student by type of school;

§

Land: Acres per student by type of school;

§

Support facilities: Square feet per student; and

§

Buses: Number of buses per student.

A credit for offsetting revenue is included in the education facility impact fee to account for other forms
of payment for Williamson County School capacity expansion improvements. Further detail on the
approach, level-of-service standards, costs, and credits is provided in the body of this report.

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ENROLLMENT PROJECTIONS AND STUDENT GENERATION RATES
ENROLLMENT PROJECTIONS
Enrollment projections were provided by Williamson County School staff and are based on active
developments as of April 2019. As shown in Figure 3, enrollment in Williamson County Schools in August
of 2019 is 40,998. By the school year 2023-24, Williamson County Schools is projected to have a total
enrollment of 48,274, a 4-year increase of 7,276 students.
Figure 3: Enrollment Projections
Enrollment Projections [1]
Elementary and Middle
Net Change
High
Net Change
Total
Net Change

2019-20 [2]
27,481
13,517
40,998

2020-21
28,959
1,478
14,157
640
43,116
2,118

2021-22
30,129
1,170
14,700
543
44,829
1,713

2022-23
31,311
1,182
15,231
531
46,542
1,713

2023-24 Total Change Annual Growth Rate
32,490
3.6%
1,179
5,009
15,784
3.4%
553
2,267
48,274
3.5%
1,732
7,276

[1] Williamson County Schools projections. Does not include PK/EC
[2] August 12, 2019 attendance

STUDENT GENERATION RATES
Demand for additional school capacity will come from new residential development. To determine the
level of this demand, student generation rates are used. The term “student generation rate” refers to the
number of public school students per housing unit in the Williamson County School system. Public school
students are a subset of school-aged children, which includes students in private schools and homeschooled children.
Student generation rates are important demographic factors that help account for variations in demand
for school facilities by type of housing. Students per housing unit are held constant over the projection
period since the impact fees represent a “snapshot approach” of current level-of-service standards and
costs.

Student Generation Rates by Unit Size
Student generation rates by unit size for Williamson County can be derived using custom tabulations of
demographic data from survey responses provided by the U.S. Census Bureau in files known as Public Use
Micro-Data Samples (PUMS). TischlerBise used Census American Community Survey (ACS) 1-Year 2017
PUMS data to derive number of students per housing unit by type of unit. Williamson County is
coterminous with Public Use Micro-Data Area (PUMA) 2600. This is shown in Figure 4.

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 Education Facility Impact Fee Report

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Figure 4: School Age Children by Bedroom Count

Estimated Williamson County Public School Students
by Housing Unit Type and Number of Bedrooms
K-8 Students

Bedrooms
0-2
3
1,189
5,787

All Housing

4+
16,708

TOTAL
9-12 Students

0-2

All Housing

Bedrooms
3
515
2,953

4+
9,058

12,868

36,211

38,683

4+
40,393

TOTAL
76,485

Housing Units
76,485

40,393

76,485

76,485

Grand Total (all grades)
Bedrooms
0-2
3
10,425
25,667

All Housing
TOTAL

10,425

25,667

25,815

TOTAL
12,526
0
12,526

TOTAL

Housing Units

TOTAL
23,685
0
23,685

Students
Williamson Co.
2017

Source: Cross tabulation by TischlerBise using
Census Bureau, 5-Year 2017 American Community Survey
PUMS data for Tennessee PUMA 02600.

Using the PUMS data files, TischlerBise first calculated student generation rates based on the number of
students in residential units of different bedroom sizes. This was done for each school level (i.e. grades K8 and grades 9-12) by housing unit type. Unadjusted student generation rates by housing unit size were
calculated by dividing the number of students in each type of unit by the number of units in each size
category from the sample. These rates were then adjusted using control totals based on 2017 Williamson
County enrollment figures and American Community Survey housing unit estimates (Figure 5).

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Figure 5: Student Generation Rates by Bedroom Count
Public School Students by Bedroom Range
Williamson County 2017 PUMS Survey Results
Grades K-8 Housing Units
Unadjusted
Bedroom Range Students [1]
[1]
Housing Mix Students/HU
Two or less
60
526
14%
0.114
Three
292
1,295
34%
0.225
Four or more
843
2,038
53%
0.414
Total
1,195
3,859
0.310

Adjusted
Students/HU [2]
0.124
0.246
0.451
0.338

Grades 9-12 Housing Units
Unadjusted
Bedroom Range Students [1]
[1]
Housing Mix Students/HU
Two or less
26
526
14%
0.049
Three
149
1,295
34%
0.115

Adjusted
Students/HU [2]
0.051
0.118

Four or more
Total

457
632

2,038
3,859

53%

0.224
0.164

0.230
0.168

[1] Source: American Community Survey, Public Use Microdata Sample for TN PUMA 2600, 2017 5-Year data
[2] Adjusted multipliers are scaled to make the average PUMS value match control totals based on 2017
Williamson County Fall enrollment and housing unit estimates from ACS table B25024

To convert bedroom count rates to rates by home size, TischlerBise used data from the U.S. Census
Bureau’s Survey of Construction Microdata (2013) for Region 6 (East South Central). These data indicated
that dwelling units in this region averaged 1,264 square feet for two-bedroom units, 1,967 square feet for
three bedroom units, and 3,438 square feet for units with four or more bedrooms. These averages were
then used to conduct a fitted curve analysis to determine the student generation rates for various square
footage totals. This analysis was repeated for both the grades K-8 school level (Figure 6) and the grades
9-12 school level (Figure 7).

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 Education Facility Impact Fee Report

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Figure 6: Student Generation Rates for Grades K-8 by Unit Size
Actual Averages per Hsg Unit
Bedrooms
Square Feet
K-8 SGR
Two or less
1,305
0.124
Three
2,092
0.246
Four or more
3,651
0.451

Average dwelling size by bedroom
range is from 2017 Survey of
Construction Microdata, U.S.
Census Bureau.
Average students per housing unit
by bedroom range are derived
from 2017 5-Year ACS PUMS data
for TN PUMA 2600 (Williamson
County).

K-8 Public School Students per Dwelling by Size
Williamson County, TN

0.5

Students per Housing Unit

Fitted-Curve Values
Square Feet K-8 SGR
1,400
0.136
1,900
0.234
2,400
0.308
2,900
0.369
3,400
0.419
3,900
0.463

0.4

0.3

y = 0.3193ln(x) - 2.177
R² = 0.9905

0.2

0.1

0
0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

Square Feet of Finished Living Space

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 Education Facility Impact Fee Report

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Figure 7: Student Generation Rates for Grades K-8 by Unit Size
Actual Averages per Hsg Unit
Bedrooms
Square Feet 9-12 SGR
Two or less
1,305
0.051
Three
2,092
0.118
Four or more
3,651
0.230

Average dwelling size by bedroom
range is from 2017 Survey of
Construction Microdata, U.S.
Census Bureau.
Average students per housing unit
by bedroom range are derived
from 2017 5-Year ACS PUMS data
for TN PUMA 2600 (Williamson
County).

9-12 Public School Students per Dwelling by Size
Williamson County, TN

0.25

Students per Housing Unit

Fitted-Curve Values
Square Feet
9-12 SGR
1,400
0.058
1,900
0.111
2,400
0.152
2,900
0.185
3,400
0.213
3,900
0.237

0.2

0.15

y = 0.1748ln(x) - 1.2084
R² = 0.9907

0.1

0.05

0
0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

Square Feet of Finished Living Space

Student generation rates by unit size were derived by adding the student generation rates for each school
level. As such, the student generation rates are 0.194 for a unit of 1,399 square feet or less, 0.345 for a
unit of 1,400 to 1,899 square feet, 0.460 for a unit of 1,900 to 2,399 square feet, 0.554 for a unit of 2,400
to 2,899 square feet, 0.632 for a unit of 2,900 to 3,399 square feet, and 0.700 for a unit of 3,400 square
feet or more. These rates are shown below in Figure 8

13

 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 8: Student Generation Rates by Unit Size
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

K-8
0.136
0.234
0.308
0.369
0.419
0.463

School Level
9-12
0.058
0.111
0.152
0.185
0.213
0.237

Total
0.194
0.345
0.460
0.554
0.632
0.700

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 Education Facility Impact Fee Report

Williamson County, Tennessee

EDUCATION FACILITY IMPACT FEES: WILLIAMSON COUNTY SCHOOLS
METHODOLOGY
The Williamson County Schools education facility impact fee methodology is based on current average
public school student generation rates, level-of-service standards, and local costs. Figure 9 illustrates the
methodology used to calculate the fee. The education facility impact fees use an incremental expansion
approach, which documents the current levels-of-service for public facilities in both quantitative and
qualitative measures. The intent is to use impact fee revenue to expand or provide additional facilities, as
needed to accommodate new development, based on the current level-of-service standards and costs to
provide capital improvements. All school levels are included in the fees. Costs for school buildings, land,
support facilities, and buses are included in the fee. Finally, a credit for offsetting revenue is also included.
Demand for additional school capacity will come from new residential development. To determine the
level of this demand, student generation rates are used. The term “student generation rate” refers to the
number of public school students per housing unit in the Williamson County School system. Public school
students are a subset of school-aged children, which includes students in private schools and homeschooled children.
Student generation rates are important demographic factors that help account for variations in demand
for school facilities by type of housing. Students per housing unit are held constant over the projection
period since the impact fees represent a “snapshot approach” of current level-of-service standards and
costs.

15

 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 9. Impact Fee Methodology Chart
Residential
Development

Students per Housing Unit by
Type of Unit (Student Generation
Rate)

Multiplied By Net Local Capital
Cost per Student

School Construction
Cost per Student

Plus Land
Cost per Student

Plus Support Facility Cost per
Student

Plus Bus
Cost per Student

less Offsetting Revenue Credit
Per Student

BUILDING LEVEL OF SERVICE STANDARDS
This section provides current inventories of elementary, middle, and high schools in the Williamson
County School system. The data contained in these tables are used to determine infrastructure standards
for school buildings and sites on which the impact fees are based.

WCS Elementary and Middle Schools (K-8)
The inventory and current level-of-service for Williamson County elementary and middle schools are
shown below in Figure 10. Elementary and middle school buildings have a total of 4,000,307 square feet
of floor area on 1,004.16 acres of land. In August 2019, total enrollment in all elementary and middle
schools was 26,996, or 83% of permanent capacity (33,251). Level-of-service factors for Williamson
County elementary and middle schools are also shown in Figure 10. Since enrollment is presently lower
than capacity, capacity is used to determine the level-of-service standards for elementary and middle
school buildings and acreage highlighted in the figure below. The level-of-service factors on which the
impact fees are based are 120.31 square feet and 0.031 acres per student.

16

 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 10. Elementary and Middle Schools Level-of-Service Standards (K-8)
ELEMENTARY AND MIDDLE SCHOOLS (Grades K-8) [1]
Inventory, Enrollment, and Utilization
Facility

Site Acreage

Allendale ES
Bethesda ES
Brentwood MS
Chapman's Retreat ES
Clovercroft ES
College Grove ES
Creekside ES
Crockett ES [2]
Edmondson ES
Fairview ES
Fairview MS
Grassland ES
Grassland MS
Heritage ES
Heritage MS
Hillsboro ES
Hunters Bend ES
Jordan ES
Kenrose ES
Lipscomb ES
Longview ES
Mill Creek ES/MS [3]
Nolensville ES
Oak View ES
Page MS
Pearre Creek ES
Scales ES
Spring Station MS
Sunset ES/MS
Thompson Station ES/MS
Trinity ES
Walnut Grove ES
Westwood ES
Winstead ES
Woodland MS [2]
Total

25.00
22.00
25.00
20.00
22.72
20.00
64.00
19.85
20.00
11.50
10.00
25.00
32.00
30.00
41.00
37.00
20.00
73.00
20.00
26.00
21.00
45.52
16.90
20.00
25.00
14.00
25.00
35.00
64.00
76.00
21.00
19.00
22.00
22.90
12.77
1,004.16

Building
Square Footage
118,992
84,102
119,395
86,600
118,992
68,569
121,000
93,182
85,221
58,581
109,997
90,000
150,522
82,000
127,843
113,152
68,625
121,000
92,048
78,435
121,000
234,000
118,000
73,800
190,688
118,992
83,544
137,200
215,950
235,000
86,661
97,474
86,805
90,110
122,827
4,000,307

Permanent
Capacity
890
780
1,500
805
890
730
890
870
825
715
764
870
1,160
805
1,185
597
780
890
910
780
935
1,600
890
695
1,200
890
940
971
1,674
1,600
870
780
805
790
975
33,251

Enrollment
(8/12/2019) [1]
680
517
1,323
707
754
632
516
648
756
509
548
561
990
612
1,012
600
478
413
775
628
884
1,516
775
369
1,118
653
806
1,033
1,307
1,385
792
578
525
587
1,009
26,996

Demand Units
(Permanent Capacity)

Site
Acreage

Building
Square Footage

33,251

0.030

120.31

Utilization
76%
66%
88%
88%
85%
87%
58%
74%
92%
71%
72%
64%
85%
76%
85%
101%
61%
46%
85%
81%
95%
95%
87%
53%
93%
73%
86%
106%
78%
87%
91%
74%
65%
74%
103%
81%

Elementary and Middle School Levels of Service

LOS per Student
based on Capacity
[1] Does not include PK/EC

[2] Shared campus. Acreage is derived as a percentage of shared campus building square footage devoted to each school level.
[3] Located on same land as Nolensville High; acreage derived as a percentage of square footage.

17

 Education Facility Impact Fee Report

Williamson County, Tennessee

WCS High Schools
The inventory and current levels-of-service for WCS high schools are shown below in Figure 11. High
school buildings have a total of 2,342,941 square feet of floor area on 488.88 acres of land. In August
2019, total enrollment in all high schools was 13,517, or 91% of permanent capacity (14,827). Level-ofservice factors for Williamson County high schools are also shown in Figure 11. Since enrollment is
presently lower than capacity, capacity is used to determine the level-of-service standards for high school
buildings and acreage, highlighted in the figure below. The level-of-service factors on which the impact
fees are based are 158.02 square feet and 0.033 acres per student.
Figure 11. High Schools Level-of-Service Standards
HIGH SCHOOLS (Grades 9-12) [1]
Inventory, Enrollment, and Utilization
Facility
Brentwood HS
Centennial HS
Fairview HS
Franklin HS
Independence HS
Nolensville HS
Page HS
Ravenwood HS
Renaissance HS
Summit HS
Total

Site Acreage

Building
Square Footage

Permanent
Capacity

Enrollment
(8/12/2019) [1]

Utilization

32.00
55.00
34.00
39.40
83.55
50.48
41.00
80.00
1.72
71.73
488.88

299,032
263,134
198,730
305,989
299,529
259,495
187,550
253,482
17,000
259,000
2,342,941

2,000
1,758
1,042
2,000
1,671
1,671
1,215
1,649
150
1,671
14,827

1,727
1,655
721
1,752
1,892
1,163
1,131
1,671
182
1,623
13,517

86%
94%
69%
88%
113%
70%
93%
101%
121%
97%
91%

Demand Units
(Permanent Capacity)

Site
Acreage

Building
Square Footage

14,827

0.033

158.02

High School Levels of Service

LOS per Student
based on Capacity
[1] Does not include EC

LAND ACQUISITION COSTS
Williamson County Schools will need to purchase land for future school sites to accommodate school
capital needs brought about by growth in the County. As shown in Figure 12 below, Williamson County
Schools has acquired 279.86 acres since 2013 at a total cost of $19,027,091. This results in an average cost
per acre of $67,988.

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 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 12. Land Acquisition Costs
Facility
Jordan Elementary/Middle
Creekside Elementary

Year
2016
2018

Acreage
73.00
64.00

Cost
$8,700,000
$2,390,000

Cost per Acre
$119,178
$37,344

Nolensville High and Mill Creek
Elementary and Middle
Thompson's Station Elementary and Middle
Total

2013
2016

96.00
46.86
279.86

$4,010,577
$3,926,514
$19,027,091

$41,777
$83,792
$67,988

Source: Williamson County Schools

SCHOOL CONSTRUCTION COSTS
TischlerBise analyzed costs for school construction for Williamson County Schools. Costs for recently
completed school projects were provided by Williamson County Schools. Current school costs represent
the average costs to construct elementary and middle schools and high schools in the Williamson County
School system. As shown in Figure 13, construction costs for elementary/middle schools range between
$173 and $221 per square foot, with a weighted average cost of $196.49. The average cost per square
foot assumption for the high school level is based on the recently completed Nolensville High School,
which had an average cost per square foot of $176.46. These figures do not include the cost of land.
Figure 13. School Project Costs

Jordan Elementary School
Creekside Elementary School
Thompson Station Elementary/Middle School

Square
Footage
121,000
121,000
235,000

$26,233,549
$26,810,000
$41,073,486

Cost per
Square Foot
$216.81
$221.57
$174.78

Total

477,000

$94,117,035

$197.31

259,495

$45,789,423

$176.46

Facility

Nolensville High

Cost

Source: Williamson County Schools

SUPPORT FACILITIES LEVEL-OF-SERVICE AND COSTS
The impact fees also include costs to provide support facilities such as administrative office space,
maintenance facilities, and storage buildings. The Williamson County Schools support facilities are shown
below in Figure 14 and total 56,673 square feet. This figure is divided by the August 2019 enrollment of
40,513 to yield a level-of-service of 1.38 square feet per student. This level-of-service standard is then
multiplied by a replacement cost estimate of $165 per square foot (provided by WCS staff), resulting in a
cost per student of $230.82.

19

 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 14. Support Facilities Level-of-Service and Costs
Facility
Operations Support Bldg.
Textbook Bldg.
Transportation
Equipment Shed.
Total
Cost per sq. ft.*
Total Replacement Cost

Square Footage
28,012
8,871
13,674
6,116
56,673
$165
$9,351,045

Enrollment (8/12/2019)
Square Feet per Student
Cost per Student
*Provided by County Staff

40,513
1.40
$230.82

BUS LEVEL-OF-SERVICE AND COSTS
Another infrastructure component included in the impact fee is buses. New buses, both regular and those
designed to serve students with special needs, will need to be purchased to accommodate increased
enrollment. Williamson County Schools currently owns a fleet of 235 regular buses and 65 special
education buses. The current value of the fleet is estimated at approximately $28.3 million, which equates
to a current cost of $698.55 per student ($28,300,535 / 40,513 enrollment). Level-of-service and costs are
provided below in Figure 15 for the Williamson County School fleet.
Figure 15. Buses Level-of-Service and Costs
Type
78 Passenger Bus
84 Passesnger Bus
Special Education
Total

Units
48
187
65
300
Average

Unit Cost
$85,903
$95,633
$96,828
$94,335
$94,335

Enrollment (8/12/2019)
Buses per Student
Cost Per Student

Total
$4,123,344
$17,883,371
$6,293,820
$28,300,535

40,513
0.007
$698.55

Source: Williamson County Schools

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 Education Facility Impact Fee Report

Williamson County, Tennessee

CREDIT FOR OFFSETTING REVENUES
Because the County imposes two privilege taxes on new development, a credit is necessary since new
residential units that will pay the education facility impact fee will also contribute to future school capacity
projects through the payment of one-time privilege taxes.
The County has two privilege taxes, one dedicated to schools with 30% going to the municipalities, and
another which the County has sole discretion on its use, including allocating revenue to schools. In
addition, the County allocates varying percentages of privilege tax to debt service, meaning there is an
annual fluctuation of revenue from both privilege tax and General Fund revenue that could potentially be
construed as a “double payment.” There is also General Fund and privilege tax revenue that can
potentially be used for non-debt expenditures on capacity and/or technology, etc. Rather than devise a
complicated credit system requiring annual adjustments, based on budgeted expenditures or some other
alternative, we are proposing a rather straightforward method, which is conservative in nature, meaning
we are probably overestimating the credit.
As shown in Figure 16, the majority of growth-related capital costs for growth-related schools are funded
through bonded debt. Conversations with Williamson County indicates suggest that we include a credit
for offsetting revenue for existing principal and interest on existing debt service payments shown in Figure
16. Annual principal and interest payments are divided by projected student enrollment in each year to
get a per student credit. (For example, in FY 2020, the total amount of K-8 principal and interest to be paid
of $27,558,035 is divided by projected enrollment of 26,996 for a payment per student of $1020.82.) To
account for the time value of money, annual payments per student are discounted using a net present
value formula based on an average current interest rate of 2.32 percent. The total net present value of
future principal payments per student is $10,023.30. This amount is subtracted from the gross capital cost
per student amount to derive a net capital cost per student for school facilities. The same calculation is
completed for Grades 9-12, resulting in a credit of $12,009.04.

21

 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 16. Credit for Offsetting Revenues
Grades K-8

Grades 9-12

Year

Principal and
Interest

Projected
Enrollment [1]

Payment per
Student

Year

Principal and
Interest

Projected
Enrollment [1]

Payment per
Student

2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
Total

$27,558,035
$31,344,188
$28,794,407
$27,906,577
$27,778,158
$31,553,542
$29,272,885
$27,420,030
$25,368,650
$23,662,708
$22,101,994
$20,260,319
$20,252,819
$20,285,109
$19,934,063
$13,901,675
$12,884,788
$11,887,756
$9,224,950
$3,629,600
$435,022,253

26,996
28,959
30,129
31,311
32,490
33,864
35,237
36,611
37,984
39,358
40,731
42,105
43,478
44,852
46,225
47,599
48,972
50,346
51,719
53,093

$1,020.82
$1,082.36
$955.70
$891.27
$854.98
$864.44
$778.16
$748.97
$667.88
$601.22
$542.63
$481.19
$465.82
$452.27
$431.24
$292.06
$263.11
$236.12
$178.37
$68.36
$11,876.98

2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
Total

$21,350,700
$19,743,974
$17,413,245
$17,356,161
$17,061,387
$16,244,495
$14,891,961
$14,380,643
$14,107,648
$13,393,991
$12,893,136
$10,681,424
$10,655,536
$10,659,666
$10,373,779
$5,118,826
$3,772,191
$3,771,516
$3,568,988
$1,216,800
$238,656,067

13,517
14,157
14,700
15,231
15,784
16,351
16,918
17,484
18,051
18,618
19,185
19,751
20,318
20,885
21,452
22,018
22,585
23,152
23,719
24,285

$1,579.54
$1,394.64
$1,184.57
$1,139.53
$1,080.93
$993.50
$880.27
$822.49
$781.54
$719.42
$672.06
$540.80
$524.44
$510.40
$483.59
$232.48
$167.02
$162.90
$150.47

Discount Rate [2]
Net Present Value

2.32%
$10,023.30

$14,020.62
Discount Rate [2]
Net Present Value

2.32%
$12,009.04

[1] Enrollment beyond SY 2023-24 projected using average annual increase
from SY 2019-20 to SY 2023-24

[1] Enrollment beyond SY 2023-24 projected using average annual increase
from SY 2019-20 to SY 2023-24

[2] Interest rate at which the County has recently issued debt

[2] Interest rate at which the County has recently issued debt

MAXIMUM SUPPORTABLE EDUCATION FACILITY IMPACT FEES FOR WILLIAMSON COUNTY
SCHOOLS
Factors used to derive the Williamson County School impact fee are summarized in Figure 17. Education
facility impact fees are based on student generation rates (i.e., public school students per housing unit)
and are only assessed against residential development. Level-of-service standards are based on current
costs per student for school buildings, land, support facilities, and buses, as described in the previous
sections and summarized below.
The total gross capital cost per student is the sum of the boxed cost components. For example, for the
elementary and middle school component, the calculation is as follows: $23,738 [building construction] +
$2,053 [land acquisition] + $231 [support facilities] + $699 [buses] = $26,720 total gross cost per student.
The credit for offsetting revenue ($10,023) is then subtracted from the gross local capital cost per student
to derive the net local capital cost per student ($16,697) for elementary and middle schools. The same
approach is followed for high schools.

22

 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 17. Education Facility Impact Fee Input Variables
INPUT VARIABLES: Williamson Co. Schools
School Level
Public School Students per Housing Unit
K-8

9-12

Total

0.136
0.234
0.308
0.369
0.419
0.463

0.058
0.111
0.152
0.185
0.213
0.237

0.194
0.345
0.460
0.554
0.632
0.700

Square Feet per Student
Cost per Sq. Ft.
Building Construction Cost per Student

K-8
120.31
$197
$23,738

9-12
158.02
$176
$27,883

Acres per Student
Cost per Acre
Land Cost per Student

0.030
$67,988
$2,053

0.033
$67,988
$2,242

1.40
$165
$231

1.40
$165
$231

Buses/Vehicles per Student
Weighted Average Cost per Bus/Vehicle
Bus/Vehicle Cost per Student

0.007
$94,335
$699

0.007
$94,335
$699

Total Gross Cost Per Student

$26,720

$31,054

($10,023)
$16,697

($12,009)
$19,045

Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more
Current Level of Service Standards

Operations/Support Facilities per Student (Sq. Ft.)
Cost per Sq. Ft.
Operations/Support Facility Cost per Student

Credit for Offsetting Revenue per Student
Total Net Capital Cost per Student

Figure 18 shows the schedule of maximum supportable impact fees for WCS by unit size. The fees are
calculated by multiplying the student generation rate for each housing type (shown at the top of Figure
18) by the net capital cost per student for both types of school. Each component is then added together
to derive the total public school impact fee.
For example, for a unit sized 1,400 to 1,899 square feet, the grades K-8 school portion of the fee is
calculated by multiplying the student generation rate of 0.234 by the net local capital cost per K-8 student
of $16,697, which results in a fee of $3,907 (truncated). This calculation is repeated for high schools
23

 Education Facility Impact Fee Report

Williamson County, Tennessee

(grades 9-12). The two portions of the fee are added together to calculate the total fee by type of
residential unit (i.e., for a unit sized 1,400 to 1,899 square feet: $3,907 + $2,114 = $6,021.)1
Figure 18. Maximum Supportable Education Facility Impact Fees: WCS
INPUT VARIABLES: Williamson Co. Schools Impact Fees
School Level
Public School Students per Housing Unit
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more
Cost Factors
Total Net Local Capital Cost per Student

K-8

9-12

Total

0.136
0.234
0.308
0.369
0.419
0.463

0.058
0.111
0.152
0.185
0.213
0.237

0.194
0.345
0.460
0.554
0.632
0.700

$16,697

$19,045

MAXIMUM ALLOWABLE EDUCATION FACILITY IMPACT FEES: Williamson Co. Schools
Impact Fee per Housing Unit*
K-8
9-12
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

$2,271
$3,907
$5,143
$6,161
$6,996
$7,731

$1,105
$2,114
$2,895
$3,523
$4,057
$4,514

TOTAL

$3,375
$6,021
$8,038
$9,685
$11,053
$12,244

*Fees do not apply to age-restricted units

As noted above, Williamson County is served by two school systems, Williamson County Schools and the
Franklin Special School District. Students living in FSSD attend these schools from kindergarten to eighth
grade, after which they attend WCS high schools. This report details only impact fees for Williamson
County Schools. New residential construction located in FSSD will be charged for only the high school
component of the WCS impact fee, since students generated from these homes will only attend WCS for
high school. Figure 19 provides the schedule of maximum supportable school impact fees within FSSD
boundaries by unit size. For example, for a unit sized 1,400 to 1,899 square feet, the fee is $2,114.

Because the analysis uses figures carried to their ultimate decimal places, the sums and products shown may not equal the sum
or product if the reader replicates the calculation with the factors shown in the report.
1

24

 Education Facility Impact Fee Report

Williamson County, Tennessee

Figure 19. WCS Maximum Supportable Education Facility Impact Fees within Franklin Special School
District
INPUT VARIABLES: Williamson Co. Schools Impact Fees
(within Franklin Special School District boundaries)
Public School Students per Housing Unit
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

School Level
9-12
0.058
0.111
0.152
0.185
0.213
0.237

Cost Factors
Total Net Local Capital Cost per Student

$19,045

MAXIMUM ALLOWABLE EDUCATION FACILITY IMPACT FEES: Williamson Co. Schools
(within Franklin Special School District boundaries)
Impact Fee per Housing Unit*
Dwelling Unit Size
1,399 square feet or less
1,400 - 1,899 square feet
1,900 - 2,399 square feet
2,400 - 2,899 square feet
2,900 - 3,399 square feet
3,400 square feet or more

School Level
9-12
$1,105
$2,114
$2,895
$3,523
$4,057
$4,514

*Fees do not apply to age-restricted units

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 Education Facility Impact Fee Report

Williamson County, Tennessee

IMPLEMENTATION AND ADMINISTRATION
ACCOUNTING
Impact fees should be paid at time of building permit. Certain accounting procedures should be followed
by the County. For example, monies received should be placed in a separate fund and accounted for
separately and may only be used for the purposes authorized in the impact fee ordinance. Interest earned
on monies in the separate fund should be credited to the fund.

SITE-SPECIFIC CREDITS
A site-specific credit should be considered for contributions of system improvements that have been
included in the impact fee calculations. If a developer constructs the type of system improvements
included in the fee calculations, it will be necessary to either reimburse the developer or provide a credit
against the fees for that portion of the fee. The latter option is more difficult to administer because it
creates unique fees for specific geographic areas. Based on TischlerBise’s experience, it is better for the
County to establish a reimbursement agreement with the developer constructing the system
improvement. The reimbursement agreement should be limited to a payback period of no more than ten
years and the County should not pay interest on the outstanding balance. The developer must provide
sufficient documentation of the actual cost incurred for the system improvement. The County should only
agree to pay the lesser of the actual construction cost or the estimated cost used in the impact fee
analysis. If the County pays more than the cost used in the fee analysis, there will be insufficient fee
revenue. Reimbursement agreements should only obligate the County to reimburse developers annually
according to actual fee collections from the benefiting area.

COLLECTION AND EXPENDITURE ZONES
The reasonableness of impact fees is determined in part by their relationship to the local government’s
burden to provide necessary public facilities. The need to show a substantial benefit usually requires
communities to evaluate collection and expenditure zones for public facilities that have distinct
geographic service areas. For the County School system, one area is appropriate because capacity
improvements are needed at all levels throughout the County system and County schools will occasionally
re-district to accommodate growth and available capacity.

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