The 1-acre line and the 2-acre line

Last checked: October 20, 2026 against the source documents. Based on: CGP sections 1.3.1.A, 3.1.1.G, 3.1.2, 3.1.6, 3.2.1, 3.2.7, 3.2.10, 4.2, 4.3, 5.2.C, 7.1 and Appendix A; SC Reg. 72-305 and 72-307.

Two numbers come up most for small builders. One acre decides whether permit coverage is needed. Two acres decides who must prepare the plan and who may do the inspections, but the permit words the 2-acre line differently in different sections, so we quote it exactly.

The 1-acre line: is coverage needed?

The permit covers “construction activities including clearing, grading, filling, demolition that results in soil exposure, excavating and other land disturbing activities of one acre or more”. [CGP 1.3.1.A, p.6]
Less than one acre still needs coverage “if the construction activities at the site are part of a larger common plan of development or sale (LCP) that comprise of at least one acre of land disturbance”. [CGP 1.3.1.A, p.6]
Definitions: a “large construction activity” disturbs five acres or more (or is part of an LCP that will). A “small construction activity” disturbs one acre or more and less than five (or is part of an LCP that will), and there are extra rules for coastal counties. [CGP App. A, pp.73, 82]

The 2-acre line: three different wordings

Rule	Exact wording in the permit	What the permit says
Who prepares the C-SWPPP	“For construction sites that disturb more than 2 acres” [CGP 3.1.2.B, p.25]	The plan must be “prepared, amended when necessary, certified, and stamped” by a registered professional engineer, a registered landscape architect, a Tier B land surveyor, or certain federal government employees. [CGP 3.1.2.B, p.25] For two acres or less that are not part of an LCP, SC Regulation 72-305 says the simplified plan “does not require approval by the implementing agency and does not require preparation or certification by the designers specified in R.72-305H and R.72-305I” [REG 72-305.B(1), p.14], and R.72-307H calls for a “sketched plan (engineer's, Tier B surveyor's or landscape architect's seal not required)”. [REG 72-307.H(5), p.23] SCDES's web page says that “In most cases” the SWPPP must be prepared by a licensed PE, Tier B land surveyor, or landscape architect. [CA] Unconfirmed, verify with SCDES and your MS4: who may prepare plans for sites of 2 acres or less, including sites that are part of an LCP. The permit (3.1.5.A) still requires C-SWPPP approval before construction, while R.72-305.B(1) says the small-site plan doesn't need approval. Coastal sites have an extra rule in CGP 3.1.2.D.
Who may do the inspections	“For Projects that disturb more than 2 acres” and “For Projects that disturb 2 acres or less, and that are not part of an LCP” [CGP 4.2.E, p.54]	More than 2 acres: “qualified personnel”, meaning the C-SWPPP preparer; a person with equivalent registration who has the required knowledge and skills; a person under the direct supervision of someone qualified to prepare a C-SWPPP; or “An individual who has been certified through a Construction Site Inspector Certification Course that has been approved by SCDES”. [CGP 4.2.E, p.54] SCDES's web page says “At present Clemson University's CEPSCI course meets this requirement.” [CA] 2 acres or less, not part of an LCP: “the Permittee or his designee may perform these inspections provided the preparer of the C-SWPPP explains the OS-SWPPP including implementation along with the inspection requirements to the person who will be conducting the inspections”. [CGP 4.2.E.I, p.54] SCDES and regulated MS4s “reserve the right to require that inspections be performed by an inspector meeting the requirements of 4.2.E.I for construction sites less than two acres in size that drain to Sensitive Waters”. [CGP 4.2.E.II, p.54] Unconfirmed, verify with SCDES: 4.2.E.II points back to 4.2.E.I (the permittee/designee rule), which may be a cross-reference error. It also doesn't say who may inspect sites of 2 acres or less that ARE part of an LCP.
Maps in the C-SWPPP	“sites 2 acres and greater or sites that are part of an LCP that disturb 2 acres or more collectively” vs. “sites that are less than 2 acres and not part of an LCP” [CGP 3.2.7.A, p.41; 3.2.7.B, p.42]	The larger sites need the full map set (topographic, soils, floodway, vicinity, and drainage maps). [CGP 3.2.7.A, p.41] Sites under 2 acres and not part of an LCP need a shorter list: a site location drawing, boundary lines, a topographic map if the implementing agency requires one, and the locations of the stormwater and sediment control measures. [CGP 3.2.7.B, p.42] The narrative for those smaller sites must also describe the sediment control plan, the topography and soils, and adjacent properties. [CGP 3.2.1.A.VII, p.30]
Notice of Termination	“For Projects disturbing more than 2 acres” [CGP 5.2.C.VI, p.59]	A certification signed by the C-SWPPP preparer (or a person with equivalent registration) that the work was done in accordance with the approved OS-SWPPP and the CGP. [CGP 5.2.C.VI, p.59]

Unconfirmed, verify with SCDES: how a site of exactly 2.0 acres is treated. The map rule applies at '2 acres and greater' (3.2.7.A), the preparer, inspector, and NOT rules apply at 'more than 2 acres' (3.1.2.B, 4.2.E, 5.2.C.VI), and SCDES's web page says '2 acres more'.

Larger sites have more rules. “For non-linear construction sites disturbing more than 5 acres, the Comprehensive SWPPP must be submitted with a phased erosion prevention and sediment control plan”. [CGP 3.1.1.G.II, p.23] “For construction sites subject to Regulation 72-400, that disturb 5 acres or more”, the C-SWPPP must be sealed by a registered professional engineer licensed in SC. [CGP 3.1.2.C, p.25]

Rules that apply at every size (summaries; read the quoted sections)

Inspection frequency: “at a minimum of at least once every calendar week, with no time period between inspections exceeding 9 days”, until final stabilization on all areas. [CGP 4.2.B, p.53] Areas that have reached temporary or final stabilization “may be reduced to at least once every month, as long as the stabilization is maintained and there is no additional disturbance in these areas”. [CGP 4.2.B, p.53] The permit also recommends that the contractor assess BMPs “within 24 hours of the end of a storm event of 1.0 inch or greater”. [CGP 4.2.B, p.53]
Unconfirmed, verify with SCDES: SC Regulation 72-307.B(1) says plans must provide that controls 'are inspected at least once every seven calendar days and after any storm event of greater than 0.5 inches of precipitation during any 24-hour period' (REG p.18). Ask SCDES or your MS4 how this lines up with the CGP's weekly / 9-day rule.
Rain records: an on-site rain gauge is “strongly recommended”, and permittees “may utilize data from a certified weather record (such as a personal weather station or an airport) located within reasonable proximity” instead. Recorded rainfall must be kept in a Rain Log in the on-site SWPPP, and each weekly inspection report must include rainfall for the inspection day and any significant rainfall (0.5 inches or greater) since the last inspection. [CGP 4.2.D, p.54]
BMP repairs: “maintenance must be performed within seven (7) calendar days, before the next inspection, or as reasonably possible, and before the next storm event whenever practicable”. If it takes longer than 7 days, document the reason. A BMP used inappropriately or incorrectly must be corrected “within a time frame of 48 hours of identification”. [CGP 4.3.A, pp.55-56]
Sediment removal: silt fence and similar controls when sediment “reaches 1/3 of the height of the above-ground portion of these BMPs, or before it reaches a lower height based on the manufacturer's specifications”. Sediment traps and basins “as indicated in the OS-SWPPP or when the design capacity has been reduced by 50 percent, whichever occurs first”. [CGP 4.3.A, p.56]
Stabilization: “Permittees must initiate stabilization measures immediately whenever any clearing, grading, excavating or other earth disturbing activities have permanently ceased on any portion of the site, or temporarily ceased on any portion of the site and will not resume for a period exceeding 14 calendar days.” [CGP 3.2.10.B, p.48] Where steep slopes (30% or greater) are disturbed, the C-SWPPP must “Initiate stabilization measures on any exposed steep slope area where land-disturbing activities have permanently or temporarily ceased and will not resume for a period of 7 calendar days”. [CGP 3.2.10.A.IV, pp.47-48]
Records: inspection records must be kept with the On-Site SWPPP “for at least three years from the date that permit coverage expires or is terminated”, and “The qualified inspector, as identified in section 4.2.E, must sign the inspection report.” [CGP 4.2.H, p.55] The same 3-year rule applies to the SWPPP and other permit documentation. [CGP 7.1, p.62]
On-Site SWPPP: a copy must be kept at the site from the start of construction until final stabilization. [CGP 3.1.6.A, p.26] If that isn't possible, post its location near the main entrance and make it “available within thirty (30) minutes upon request”. [CGP 3.1.6.B, p.26]

Becoming a CEPSCI inspector: Clemson's page says that, effective August 2026, Statewide Certification classes are Day One classroom instruction, then a simulated site inspection on the morning of Day Two and the certification exam (“Now Open - Book”) that afternoon. Remaining 2026 date listed: online, December 2-3, 2026. In-person classes are held at the River Center in Saluda Shoals Park, Columbia, and the Aug. 12-13, Sept. 9-10, and Oct. 14-15, 2026 sessions have passed. [CEP] Clemson's Fees and Policies page lists “Class, certification exam, materials: $395” and “Recertification class: $275”. [CEPF]

Sources for this page

Citations like “CGP 4.2.B, p.53” mean section 4.2.B of the permit, on page 53 of the PDF. Last checked October 20, 2026. Where we quote, the quote is copied from the source; where we summarize, read the quoted section before relying on it.