Construction and Noise

As a construction worker, contractor, or engineer, you should be aware of how your activities are regulated under the Montgomery County Noise Control Ordinance. With careful planning and operation, it's possible to minimize potential noise disturbances from construction activities.

Construction Noise Basics

Virtually all potential noise sources that operate permanently or semipermanently can be designed or controlled to meet the receiving property line standard. Likewise, potential sources under human control, such as electronically amplified sound, can be designed to meet the ordinance requirements.

Noise from some construction activities, however, is difficult, if not impossible, to control to the receiving property line. This is because the engineering design and technical controls that are effective on permanent stationary sources aren't practical or reasonable for a temporary, often mobile, noise source or combination of sources. The Noise Control Ordinance, therefore, contains certain standards specific to construction noise. DEP has several tools available to help mitigate and regulate this potential source of disturbance.

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Construction Noise Exemptions and Standards

The Montgomery County Noise Control Ordinance defines construction as temporary activities directly associated with site preparation, assembly, erection, repair, alteration, or demolition of structures or roadways. Construction noise levels must be measured on a receiving property, but no closer than 50 feet from the noise source.

Notice to Contractors

From 7 a.m. to 5 p.m. weekdays, construction noise levels must not exceed:

• 75 dBA without a Noise Suppression Plan (see Guidelines, (PDF, 1pp, 497K) )
• 85 dBA with a Noise Suppression Plan (see Guidelines, (PDF, 1pp, 497K) )

At all times other than 7 a.m. to 5 p.m. weekdays, the general ordinance standards in the Noise Control Ordinance must be met. The following table provides a summary of the noise standards for construction activities:

   *In most circumstances in the County, the receiving property will be considered residential.

   ** The U.S. Office of Personnel Management has a list of federally recognized holidays.

Be Aware! Construction activities are also subject to the "Noise Disturbance" provisions of the ordinance. Although a noise disturbance, as defined by the ordinance, could conceivably occur at any time, it is most likely to happen during nighttime hours. The following are examples of noise disturbances:

• Delivering materials or equipment
• Loading or unloading in a residential area
• Operating construction equipment with audible backup warning devices

The County mails copies of the revised ordinance upon request. If you have questions or comments, contact the Office of Environmental Policy and Compliance at 311.

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Tools for Regulating Construction Noise

In addition to the Noise Control Ordinance, DEP has several mechanisms for controlling and regulating construction noise.

Noise Suppression Plan

A Noise Suppression Plan is a written plan to use the most effective noise-suppression equipment, materials, and methods appropriate and reasonably available for a particular type of construction.

Several construction activities, such as pile driving and hoe ramming, might inherently exceed 75 dBA, depending on the circumstances. In those cases, the Montgomery County Noise Control Ordinance allows up to 85 dBA, provided a Noise Suppression Plan, approved by DEP, is implemented. Essentially, these plans require the best reasonably available control technology or strategy. They might involve equipment selection, scheduling, and temporary noise control devices to block or absorb the sound.

Read the full text of the Montgomery County Noise Suppression Plan Guidelines (PDF, 1pp, 497K) to learn more.

Temporary Noise Waiver

Occasionally, public works construction projects are done during hours that fall outside the County-designated normal construction hours of Monday through Friday 7 a.m. to 5 p.m. These projects are usually done in response to directives by state and local agencies to address traffic congestion and pedestrian safety issues. The Montgomery County Noise Control Ordinance allows for the issuance of a Temporary Noise Waiver to allow after-hours and nighttime construction projects if the benefit to the public offsets the noise the event will create in excess of the established limits. Refer to the application form and fee schedule below, and allow 30 days for the processing of your Temporary Noise Waiver application.

• Download a Temporary Waiver Form (PDF, 2pp, 53.4K)

The following fees apply for exemption applications:

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Active Nighttime Construction Projects with Approved Noise Waivers

View a "Noisy Sites" map of the County showing active nighttime construction projects with approved noise waivers, or check the issued temporary noise waivers listed below:

1. Edmonston Road between MD Route 355 and Lewis Avenue, Rockville
2. Judicial Center, Downtown Rockville 
3. Fenton Street between Wayne and Philadelphia Avenues (Silver Spring)
4. Executive Boulevard, between Jefferson Str. and Old Georgetown Road (Rockville)

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Tips for Construction Site Managers

Useful tips from learned from previous construction projects include the following:

• Incorporate noise control considerations in all phases of project design and planning.
• Communicate with the surrounding community early and often. Put a human face on the project and the company. Let people know what's happening and, most important, when it should be over. People are more tolerant when they know what to expect.
• "Buy quiet—rent quiet." Select equipment for its low-noise-emission design. When renting, specify the quietest equipment available, using the Noise Control Ordinance requirements as a guide. Low-noise equipment is often of better quality and durability. Most manufacturers can provide noise emission specs.
• Internal combustion equipment should be equipped with proper, well-maintained mufflers. In particular, use "critical" mufflers in noise-sensitive areas. Keep access doors and hatches closed when the units are in operation, and operate all equipment at the minimum level necessary to get the job done. (It saves fuel too!)
• Whenever possible, schedule the more noise-intense activities for less intrusive times, such as midmorning to mid-afternoon.
• Construct portable barriers around noisy non-mobile pieces of equipment, using readily available materials.
• Use lawful alternatives to factory-installed backup beepers, such as flagpersons, "Smart Alarms," or video systems.
• Purchase a sound level meter for self-monitoring and documentation.
• "Work quiet." Equal to all of the above is the awareness that noise control is an important part of the job. Everyone likes a good neighbor. Managers and supervisors should communicate that noise control is part of the job.
• Noise suppression measures can be fabricated on-site using materials at hand. Also, many equipment manufacturers provide silencing packages, both design and retrofit.

Proactive and reasonable control of construction noise results in more content communities and successful, on-schedule projects with a minimum of hassle due to noise. It also removes the inconvenience of civil penalties, abatement orders, or stop work orders.

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Calculating Sound Intensity

Noise emissions from all mechanical equipment must be expressed, in A-weighted decibels (dBA), measured at a stated reference distance. It's your responsibility to calculate the estimated sound intensity (in dBA) to ensure that it complies with the Montgomery County Noise Ordinance. The following guidance can help you:

• As a general rule, sound from a stationary source will diminish approximately 6 dBA with each doubling of distance. For example, if the sound intensity is 75 dBA at 25 feet, it will be 69 dBA at 50 feet and 63 dBA at 100 feet.
• Because of the logarithmic nature of the decibel scale, if two sources of equal sound intensity are placed in close proximity to one another, the net increase will be 3 dBA. However, if there is a difference of 10 dBA or more between the two, the lesser source will have no effect on the overall level.

These estimations are especially useful in determining equipment or facility placement (e.g. loading docks), or in the design of engineering controls. All calculations and assumptions should be submitted to the reviewing authority.

Note: Most equipment manufacturers, and especially those who produce or market in Europe or Asia, have detailed noise performance specifications for their products.

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