9.1 Scope of Incidental Street & Storm Sewer Design (G.S. 89C-3(7) & the Board Guidelines)

9.1 Scope of Incidental Street & Storm Sewer Design (G.S. 89C-3(7) & the Board Guidelines)

Drainage is 16 percent of the state-specific exam, and the Board's own description of the exam says it tests "what a PLS can do per G. S. 89C and the incidental drainage guidelines with respect to erosion control and surface drainage." The first thing to master is not hydrology — it is the boundary of your license.

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1. The Statutory Exception

North Carolina builds the authority out of two halves of the same definition. The inclusion is G.S. 89C-3(7)a.3.:

The practice of land surveying includes "Making any survey for the subdivision of any tract of land, including the topography, alignment and grades of streets and incidental drainage within the subdivision, and the preparation and perpetuation of maps, record plats, field note records, and property descriptions that represent these surveys."

The exclusion is G.S. 89C-3(7)b., which provides that the term shall not be construed to permit the design or preparation of specifications for:

Item (vi) is the hinge. Streets and storm sewers are engineering by default; they become surveying only in the narrow channel the statute cuts — incidental to a subdivision the surveyor is surveying. The Board's guideline opens by saying exactly that: "The law restricts design and preparation of the plans for the above to subdivisions only."

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2. Who Decides What Is "Incidental"

The Guidelines answer this in one sentence worth quoting in full:

"Items which are 'incidental' to a subdivision are initially determined by the designer in order to stay within that designer's expertise, and the designer's decision is then subject to this Board's determination of what is 'incidental' or what 'appertains solely to the public works needs of the proposed subdivision.'"

That is a two-stage, competence-anchored test, and it lines up with 21 NCAC 56 .0701(c), which permits a licensee to undertake assignments only when qualified by education or experience in the specific technical field. The surveyor makes the first call against their own competence; the Board reviews it after the fact.

[!CAUTION] There is no acreage limit. North Carolina publishes no "200-acre," "100-acre," or any other numeric ceiling on incidental drainage design, and no such figure appears in G.S. 89C, in 21 NCAC 56, or in the Guidelines. Prep material that supplies one is inventing a bright line the Board deliberately declined to draw. The real test is the exclusion list below plus your own competence.

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3. The Eleven Exclusions — Memorize These

The Guidelines state that items not permitted to be designed under the term "incidental streets and drainage" include but are not limited to the following:

 1. Structural sub-base, base, paving surface of the streets, super elevation,
    traffic control, etc., necessary for street design; hydraulics for drainage
    systems, and hydrology for storm conditions; trench safety conditions; pipe
    bedding, structure backfill, and all structural load conditions from traffic
    on trenches, catch basins, manholes, grates and frames -- EXCEPT that level
    of hydrology and hydraulics necessary in the performance of "incidental
    drainage" may be performed within a subdivision.

      a) Nothing prohibits use of the STANDARD sub-base, base and/or paving
         surface designs provided by NCDOT in "Subdivision Roads Minimum
         Construction Standards," where special structural design is not
         required.
      b) "Traffic control" does not prohibit the design of geometric features
         common to subdivision streets, nor the use of stop or yield signs at
         intersections.

 2. Any street or drainage system which the surveyor is not TOTALLY COMPETENT
    in all aspects of the design of the facilities.
 3. Any streets or storm sewers SEPARATE from a subdivision design.
 4. Any DAMS or RETAINING WALLS.
 5. Any major drainage ditch, storm culvert, branch, deep structure, catch
    basin, manhole, etc., requiring SPECIAL or STRUCTURAL design.
 6. Any design of major drainageways or storm sewers carrying storm sewer
    THROUGH the subdivision to drain a LARGE DRAINAGE BASIN (major drainage
    canal, creek, river, large conduit system, etc.).
 7. Any special design or selection of conduits for HIGHWAY LOADS, other than
    residential streets, or deep sewers requiring special conduit selection due
    to drainage loading.
 8. Any drainage system for the purpose or facilitation of SEWAGE DISPOSAL.
 9. Any storm sewer carrying more than a SMALL REASONABLE AMOUNT of storm water
    from lands ADJACENT to the subdivision being designed.
10. Streets designated as THOROUGHFARES or COLLECTOR STREETS in an adopted
    thoroughfare plan.
11. Any SURCHARGED storm sewers or PUMPING STATIONS.

                            (As Revised and Adopted June 8, 1989; Issued June
                             19, 1989; Names Edited November 1, 2004; Reviewed
                             September 20, 2012)

Reading item 1 correctly

Item 1 looks, on a fast read, as though it forbids hydrology and hydraulics outright — and then the same sentence gives it back: "except, that level of hydrology and hydraulics necessary in the performance of 'incidental drainage' may be performed within a subdivision." What item 1 actually excludes is the structural side of street and drainage construction: pavement structural design, superelevation, trench safety, pipe bedding, backfill, and traffic loading on structures. The hydrologic and hydraulic computations taught in Sections 9.2 and 9.3 sit inside the exception.

Sub-item (a) is a practical gift: a surveyor may use NCDOT's standard sub-base, base, and paving designs from the Subdivision Roads Minimum Construction Standards where no special structural design is required. Sub-item (b) confirms that "traffic control" does not sweep in the ordinary geometry of a subdivision street or the placement of stop and yield signs.

The four recurring themes

Exclusion 2 deserves separate attention because it is unbounded: "Any street or drainage system which the surveyor is not totally competent in all aspects of the design of the facilities." A surveyor cannot satisfy the other ten and still proceed if they cannot competently design every aspect. On an exam item that describes a technically permissible design the surveyor has never attempted, exclusion 2 is the answer.

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4. Worked Scope Judgments

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5. Consequences of Overstepping

Designing outside the incidental exception is the unlicensed practice of engineering. The exposure is layered:

• G.S. 89C-23 makes practicing or offering to practice engineering without licensure a Class 2 misdemeanor.
• G.S. 89C-10(c) lets the Board obtain an injunction in the name of the State, without bond, without alleging irreparable damage or the absence of an adequate remedy at law.
• G.S. 89C-21(a)(2) and (a)(4) expose the surveyor's own license to reprimand, suspension, refusal to renew or reinstate, revocation, additional education, or required re-examination, with a civil penalty of up to $2,000 for a land surveyor under G.S. 89C-21(c).
• 21 NCAC 56 .0701(c) independently prohibits accepting an assignment outside one's competence.

The Board's structure reinforces the point: NCBELS licenses both professions, so a surveyor's overreach into engineering is adjudicated by the same body, in front of engineer members, using the same rules.