State coverage plus a local Land Disturbance Permit, and stricter city rules in Franklin and Brentwood: what your Williamson County site needs, and the penalties for getting it wrong.
Williamson County is one of the fastest-growing and highest-value construction markets in Tennessee, and its stormwater rules reflect that. Building here means dealing with the statewide Construction General Permit plus a local land-disturbance program, and which local program applies depends on whether your site is in the unincorporated county or inside a city like Franklin or Brentwood. Each runs its own MS4.
Answer a few questions about your site and get a field-ready SWPPP built to TDEC permit TNR100000, ready to review, sign, and submit.
Get startedAny site disturbing one acre or more, including a lot within a larger common plan of development, needs coverage under Tennessee's Construction General Permit (TNR100000): a SWPPP, a Notice of Intent (CN-0940), twice-weekly inspections on form CN-1173, and a Notice of Termination at closeout. New to it? See Do I need a SWPPP in Tennessee? and the inspection requirements.
For sites in the unincorporated county, the Williamson County Engineering Division reviews construction plans against the stormwater-quality requirements of its Phase II MS4 permit and issues a Land Disturbance Permit. A few things worth knowing: the permit stays in effect for two years before it has to be renewed, the county requires Waterway Natural Area buffers along protected streams, and it backs the program with real penalties. The published civil penalty schedule includes failure to obtain a Land Disturbance Permit at $1,000 per occurrence (higher for certain repeat or serious violations), failure to install or maintain erosion controls at $500 per occurrence, and illicit discharge at $1,000 per occurrence. Letters of credit are commonly required for approved projects.
The cities run their own programs, and they are stricter than the state floor:
Franklin requires full CGP compliance plus a local stormwater and grading permit for anything over 5,000 square feet of impervious area or 10,000 square feet of land disturbance, far below the state's one-acre line. The city treats all construction sites as priority sites and inspects them monthly, and it enforces riparian buffer requirements. Track-out, failure to maintain controls, and sediment discharges are the violations they cite most.
Brentwood requires specific erosion and sediment controls to be installed before any disturbance, including a stabilized construction entrance (ASTM #1 stone over filter fabric), silt fence set along the contours, and inlet protection. Inspections run twice per calendar week at least 72 hours apart and are documented on the TDEC CN-1173 form, and the city also requires an inspection of downstream properties under its stormwater ordinance. Sediment has to be cleaned out of controls once they reach half capacity, and disturbed areas need roughly 70 percent uniform cover to be considered stabilized.
First figure out your jurisdiction, unincorporated Williamson County, Franklin, or Brentwood, because the threshold and the reviewer change. Then make sure your SWPPP matches both the state permit and the local program: the right buffers, the pre-installation controls Brentwood wants to see, and the documentation each office expects. Confirm current requirements with the county Engineering Division or the city before you disturb soil.
SWPPP Builder generates a field-ready Tennessee SWPPP built to the state Construction General Permit in about an hour. Pricing is flat and posted up front: $349 for a standard non-engineered contractor SWPPP, $99 for a single-family homebuilder plan (built on TDEC form CN-1249), and $499 when your site needs engineered or pre-approved plans. That is a fraction of the $1,500 to $5,000 a consultant typically charges, and you keep the file in your account to reuse and update as the job changes.
Yes. The state SWPPP and NOI cover you under the Construction General Permit; the county Land Disturbance Permit is a separate local approval reviewed by the county Engineering Division. Most one-acre-plus sites need both.
Yes. Franklin requires a local permit for anything over 5,000 sq ft of impervious area or 10,000 sq ft of disturbance and inspects sites monthly. Brentwood requires specific controls installed before disturbance and downstream inspections. Confirm your city first.
The county's published schedule lists failure to obtain a Land Disturbance Permit at $1,000 per occurrence, with higher amounts for certain violations, plus $500 per occurrence for failing to install or maintain erosion controls. Verify the current schedule with the county.
The county permit remains in effect for two years, after which you submit for renewal. Confirm timing and any fee with the county Engineering Division.