Sec. 59-G-2.27. Heliport and helistop.

   (a)   Purpose. Private use and public use heliports/helistops may be allowed if found to be compatible with nearby existing and master planned land uses. Compatibility must include such factors as safety, noise and the impact of proposed flight paths on nearby existing and master planned land uses. The standards and requirements of this section are intended to prevent adverse effects on existing and master planned residential use or other noise sensitive land uses that could result from heliport/helistop operations. Rotorcraft facilities shall be classified as either a public use or private use facility, and also classified as being either a heliport or helistop. It is further the intent of these regulations to encourage a small number of public use rotorcraft facilities to serve major employment centers, rather than to encourage a proliferation of private use facilities throughout the county.

   (b)   Application. All applications for heliport/helistop special exceptions must contain the following information:

      (1)   An aerial photograph showing the primary impact area, as defined in subsection (e), at a scale no less than one inch equals 400 feet showing the location of the proposed heliport/helistop; the approach and departure routes and altitudes within the primary impact area; the location of all residences, schools, churches, hospitals, and other areas used for the open assembly of people, and other noise sensitive uses that exist, have been approved for development, or are master planned within the primary impact area.

      (2)   A map showing the intended flight paths and altitudes within the secondary impact area, as defined in subsection (e). This map must indicate the proposed routes and altitude restrictions, if any, found to be acceptable by the Federal Aviation Administration.

      (3)   Information concerning the type of rotorcraft facility proposed (heliport/helistop); the nature of the use (public use/private use); type, weight and noise characteristics of rotorcraft that would use the facility; the proposed number of operations and approximate time of day that landings and departures would occur for each type of rotorcraft; and finally, the facility's proposed operating hours.

      (4)   A plan must be submitted for the Board's approval that contains the same information as required for the contents of a site plan which are enumerated in section 59-D-3.2. In addition, the plan must comply with all the heliport design guideline recommendations in the Federal Aviation Administration's Heliport Design Guide, Advisory Circular No. 150/5390-1B, dated August 22, 1977, and as subsequently amended. These guidelines are the minimum standards for the design and approval of a heliport/helistop plan. Exemptions to specific standards contained in the heliport design guide may be approved by the Board of Appeals, but only after receiving a recommendation for approval of the requested exemption from the Federal Aviation Administration.

      (5)   A detailed noise analysis showing how operations at the proposed heliport/helistop are designed both to minimize noise exposure and to comply with the noise compatibility criteria contained in subsection (e).

      (6)   For elevated facilities, an architectural drawing must be submitted which has been certified by a structural engineer licensed by the State of Maryland as demonstration that the structure will support the static and dynamic loads of rotorcraft proposed to use the facility, and that the fire safety regulations, as established in NFPA Publication #418, current edition, or any other regulations in effect at the time of application, have been satisfied.

      (7)   A copy of the “Notice of Landing Area Proposal,” a copy of the Federal Aviation Administration's response to the Notice of Landing Area Proposal, and a copy of the Air Space Determination from the Federal Aviation Administration must be submitted.

      (8)   In addition to the above requirements, the Board may require any additional information and analyses that may be relevant as the evidence of record and the public interest shall require.

   (c)   Special requirements for public use heliport/helistop. In addition to the information required in subsection (b), the following information is required for any public use heliport/helistop:

      (1)   A statement demonstrating the public need for the public use facility, in accordance with the requirements of section 59-G-1.25, title “County Need.”

      (2)   Information concerning the anticipated origin and destination of rotorcraft that would use the facility. The information should indicate any major employment centers to be served by the facility as well as a proposed schedule for commuter or other commercial operations.

   (d)   Special requirements for private use heliport/helistop. In addition to the information required in subsection (b), an application for a private use heliport/helistop must provide information that demonstrates that the proposed rotorcraft facility will not have an adverse effect on the surrounding community which might preclude the approval of a planned public heliport/helistop because of an unacceptable increase in the ambient noise levels, as defined in subsection (e).

   (e)   Noise standards.

      (1)   Impact areas. All applications for heliports/helistops must provide noise analysis sufficient to make a finding of noise compatibility at noise-sensitive locations around the facility (hereafter called the primary impact area) and along and under the principal access routes (the secondary impact area). The primary impact area includes the rotorcraft facility and the area within 4000-foot radius from the helipad. The secondary impact area includes all areas in the county along and under the principal access routes to the rotorcraft facility excluding the primary impact area.

      (2)   Noise analysis. The heliport/helistop noise analysis must include a description of detailed operational procedures to minimize noise levels affecting sensitive land uses in both the primary and secondary impact areas (“fly neighborly” procedures). Based on use of these procedures and worst-day noise scenario with peak usage of the facility, projected rotorcraft noise levels 1 (in terms of day-night average sound level or DNL) must be developed using models approved for use by the Federal Aviation Administration (see FAA Advisory Circular 150/5020-2). This worst-day operational scenario becomes the maximum allowable limit for the type, weight and noise characteristics of the rotorcraft proposed to use the facility; proposed number of operations; and approximate time of day that landings and departures could occur. Public use facilities are allowed 10 days per calendar year with operations in excess of their maximum approved level, not to exceed a 20 percent increase in the number of approved operations, so long as the extra operations do not occur during the nighttime hours (10:00 p.m. to 7:00 a.m.) or other designated noise sensitive hours.

      (3)   Noise standards. Rotorcraft operations are considered noise compatible if ambient DNL noise levels at noise sensitive areas with rotorcraft operations (post-rotorcraft ambient noise levels) exceed pre-rotorcraft ambient DNL levels by one decibel or less. If rotorcraft operations already exist in the vicinity, the cumulative impact of all operations must be calculated to determine compliance. In accordance with the purpose clause, public-use facilities must be given preference over private use facilities in the allocation of noise capacity for rotorcraft operations.

      In lieu of monitoring ambient conditions, the following noise-compatible land use planning goals for various land use types and densities must be used, as generally shown in the following table:

 

Maximum Compatible Sound Levels
Land Use/Approximate Density Residential	Day/Night Average Sound Level (DNL) in A-Weighted Decibels
Rural (less than or equal to 1 unit per acre)	55 dBA
Suburban (2 units to 15 units per acre)	60 dBA
Urban (multi-family and high rise)	65 dBA

 

Based on this table and the compatibility standard of allowing only a one-decibel increase in the ambient levels, the following table designates maximum rotorcraft sound levels:

 

Maximum Rotorcraft Sound Levels
Land Use/Approximate Density Residential	Rotorcraft Day/Night Average Sound Level (DNL)
Rural (less than or equal to 1 unit per acre)	49
Suburban (2 units to 15 units per acre)	54
Urban (multi-family and high rise)	59

 

      In cases where ambient noise levels significantly differ from those in the Maximum Compatible Sound Levels Table, 1 measurements or modeling may be performed for the purposes of establishing compatibility standards appropriate to the ambient environment. Office, commercial and industrial land uses are generally considered to be noise-compatible land uses and will not be reviewed for noise impacts with the following two exceptions: (1) situations where it appears likely that workers will be subjected to noise levels in excess of LEQ 1 = 75 dBA for an 8-hour period; (2) in CBD or Transit Station areas, where amenity spaces are provided, if it appears that noise impacts may be of such magnitude as to significantly reduce the usefulness or inhibit the proper function of these spaces for their intended purpose(s). In addition to the cumulative noise standards, the Board of Appeals may designate additional conditions for use in the public interest which may include, but not be limited to, restricting the number of rotorcraft operations, restricting the hours of operation of the facility, restricting operations of high noise generating rotorcraft during noise-sensitive hours, or any combinations thereof.

      (4)   Noise standards for on-ground facilities. All on-ground operations, with the exception of operations on the helipad, are subject to the standards of the Montgomery County Noise Control Ordinance, Chapter 31B, “Noise Control,” Montgomery County Code, as amended. In particular, heliport maintenance operations must be subject to these standards.

   (f)   Action by the Board. A helistop/heliport may be approved by the Board upon a finding that:

      (1)   The helistop/heliport complies with the provisions of Division 59-G-1.

      (2)   The helistop/heliport complies with the noise standards contained in subsection (e) of this section.

      (3)   The flight path(s) or routes proposed will minimize noise exposure to existing and master planned residential communities or other noise-sensitive activities.

      (4)   A private use helistop/heliport will not be contrary to the public interest as specified in the purpose section for helistop/heliport special exception.

   (g)   Time limits. Permission to use a site for a private use helistop/heliport may be granted by the Board for a 5-year period or such shorter period as the Board may specify in granting the special exception. The special exception may be renewed by the Board for additional periods, not to exceed 5 years each, upon the same findings required for the initial approval by the Board.

   (h)   Monitoring operations. Operators of approved heliports/ helistops must maintain an accurate log of all rotorcraft operations, specifying each operation that occurs including the type of rotorcraft and the date and time of the operation. This log must be available for inspection by the Department as part of any inspection of operations for special exceptions under Section 59-G-1.3. Failure to maintain the log or failure to make the log available to the Department as part of an inspection is a violation of the special exception approval.

(Legislative History: Ord. No. 10-39, § 1; Ord. No. 11-46, § 2; Ord. No. 13-35, § 1; Ord. No. 13-112, §1; Ord. No. 14-36, § 1; Ord. No. 14-47, § 1 ; Ord. No. 14-49, § 1 .)

 

Notes

1	1 Projected rotorcraft noise levels must be based on a 5-year projection for private use facilities, and a 20- year projection for public use facilities, in 5-year increments.
1	1 Ambient noise levels along major transportation corridors and interstate highways are likely to be higher and should be monitored to determine ambient conditions. Use of existing high-noise corridors as access routes and locations for public use facilities is strongly encouraged.
1	1 LEQ (Equivalent Sound Level). Steady sound pressure level which, for a given period of time, contains the same sound energy as the actual time-varying sound during the same time period.