TECHNICAL UNIVERSITY OF KENYA

DEPARTMENT OF CIVIL AND CONSTRUCTION ENGINEERING

ENVIRONMENTAL ENGINEERING ASSIGNMENT

111/00502

SAMSON NYAMWEYA

INSTRUCTOR: PROFESSOR THUMBI

ASSIGNMENT: NOISE FROM CONSTRUCTION, CIVIL ENGINEERING WORKS AND ITS CONTROL

Contents INTRODUCTION 3 MEASURES THAT CAN BE TAKEN TO CONTROL NOISE POLLUTION FROM CONSTRUCTION SITES. 4 Community notification 4 Operate plant in a quiet and efficient manner 4 Involve workers in minimizing noise 5 Handle complaints 5 Location of plant 5 Alternatives to reversing alarms 5 Maximize shielding 6 Schedule activities to minimize noise impacts 6

NOISE FROM CONSTRUCTION SITES
INTRODUCTION
Construction sites are often located near existing residential accommodation and by their nature are noisy and open sites. Residents will in general accept construction site noise due to their temporary status.
However, if works starts early or finishes late or if it takes place on a Saturday afternoon, Sunday or public holiday noise complaints may be likely.
In many areas, the recommended hours of operation for construction are: * Monday - Friday: Start 7:30am (with a restriction on the hours of operation heavy plant and machinery and major demolition and construction works until 8:00am) and finish at 6pm. * Saturday: Start 9am. And Finish at 1pm. * Sundays and Bank Holidays: No work permitted.
Construction plant and equipment noise levels can be described in two ways: * sound power level (Lw or SWL), or * Sound pressure level at a given distance (Lp or SPL).
The sound power level is the intrinsic noise output of plant or equipment, and does not depend on distance or orientation of the machine. There are international standards that define methods for determining the sound power level of a machine.
The sound pressure level is the noise at a given distance from plant or equipment, and the sound pressure level can change depending on the distance from the equipment and also the orientation of the equipment. The sound pressure level is meaningless without knowing the distance at which the sound pressure level is measured. Because sound pressure levels can vary with distance from plant or equipment, it is not the preferred data for comparing noise output. Sound power level is generally best for comparison of plant or equipment as it is independent of distance.
When selecting plant or equipment, the proponent should contact manufacturers or suppliers and ask for the noise level data of a range of suitable equipment. The proponent may also wish to compare the noise level data of similar equipment from different manufacturers or suppliers. There are broadly four responses that a manufacturer may give when asked for equipment noise level data:
1. Sound power level, for example, Lw 115 dB(A)
2. Sound pressure level for a given distance, for example, Lp 82 dB(A) at 7.5 m
3. Sound pressure level without specifying the distance, for example, Lp 78 dB(A)
4. No noise level data available.
The first two responses are useful as the information allows comparison of the noise output of suitable equipment. The last two responses are not useful, and in this case the proponent should either ask the manufacturer or supplier to provide more information (such as the distance at which the sound pressure level was measured), or obtain noise level data from another manufacturer or supplier.
The noise output of equipment may vary depending on operating conditions, such as idle or under load. Where possible, equipment noise levels should be compared for similar operating conditions. When undertaking on-site compliance checks, the proponent should obtain exact noise level data from the equipment manufacturer or supplier.
MEASURES THAT CAN BE TAKEN TO CONTROL NOISE POLLUTION FROM CONSTRUCTION SITES.

Community notification

* Contact potentially noise affected neighbors at the earliest possible time before any site work begins. * Inform potentially noise affected neighbors about the nature of the construction stages and the duration of noisier activities for example, excavation and rock-breaking. * Describe any noise controls, such as walls to be built first that will reduce noise, temporary noise walls, or use of silenced equipment. * Keep potentially noise affected neighbors up to date on progress. * Provide contact details on a site board at the front of the site, and maintain a complaint register suited to the scale of works. * Ask about any concerns that potentially noise affected neighbors may have and discuss possible solutions. * Provide a copy of the noise management plan, if available, to potentially noise affected neighbors.
Operate plant in a quiet and efficient manner * Where practical, undertake the noisiest works during the recommended standard hours. * Turn off plant that is not being used. * Examine, and implement where feasible and reasonable, alternative work practices which generate less noise – for example, use hydraulic rock splitters instead of rock breakers, or electric equipment instead of diesel or petrol powered equipment. * Examine, and implement where feasible and reasonable, the use of silenced equipment and noise shielding around stationary plant (such as generators), subject to manufacturers’ design requirements. * Ensure plant is regularly maintained, and repair or replace equipment that becomes noisy. * Ensure road plates are properly installed and maintained. * Arrange the work site to minimize the use of movement alarms on vehicles and mobile plant. * Locate noisy plant away from potentially noise affected neighbors or behind barriers, such as sheds or walls. * Where there are no overriding project constraints, program works so as to not affect any residence or other sensitive land use for more than a total of six nights in any four week period.

Involve workers in minimizing noise * Avoid dropping materials from a height, dropping or dragging road plates. * Talk to workers about noise from the works at the identified land uses and how it can be reduced. * Use radios and stereos indoors rather than outdoors.
Handle complaints * Keep staffs who receive telephone complaints informed regarding current and upcoming works and the relevant contacts for these works. * Handle complaints in a prompt and responsive manner. * Where there are complaints about noise from an identified work activity, review and implement, where feasible and reasonable, actions additional to those described above to minimize noise output.
Location of plant * Place as much distance as possible between the plant or equipment and residences and other sensitive land uses. * Restrict areas in which mobile plant can operate so that it is away from residences and other sensitive land uses at particular times. * Locate site vehicle entrances away from residences and other sensitive land uses. * Carry out noisy fabrication work at another site (for example, within enclosed factory premises) and then transport to site.
Alternatives to reversing alarms * Avoid use of reversing alarms by designing site layout to avoid reversing, such as by including drive-through for parking and deliveries. * Install where feasible and reasonable less annoying alternatives to the typical ‘beeper’ alarms taking into account the requirements of the Occupational Health and Safety legislation; examples are smart alarms that adjust their volume depending on the ambient level of noise and multi-frequency alarms that emit noise over a wide range of frequencies. * In all circumstances, the requirements of the relevant Occupational Health and Safety legislation must be complied with.
Maximize shielding * Reuse existing structures rather than demolish and reconstruct. * Use full enclosures, such as large sheds, with good seals fitted to doors to control noise from nighttime work. * Use temporary site buildings and materials stockpiles as noise barriers. * Schedule construction of permanent walls so that they can be used as early as possible as noise barriers. * Use natural landform as a noise barrier – place fixed equipment in cuttings, or behind earth berms. * Note large reflecting surfaces on and off site that might increase noise levels, and avoid placing noise-producing equipment in locations where reflected noise will increase noise exposure or reduce the effectiveness of mitigation measures.
Schedule activities to minimize noise impacts * Organize work to be undertaken during the recommended standard hours where possible. * Schedule work to avoid times when there are special events, such as international sporting competitions, if the construction site is in the vicinity of the venue. When works outside the recommended standard hours are planned, avoid scheduling on Sundays or public holidays. * Schedule work when neighbors are not present (for example, commercial neighbors, colleges and schools may not be present outside business hours or on weekends). * Schedule noisy activities around times of high background noise (local road traffic or when other local noise sources are active) where possible to provide masking or to reduce the amount that the construction noise intrudes above the background. * For tunneling works examine and implement, where feasible and reasonable, the possibility of stockpiling excavated material overnight in an enclosure and restrict load-out to the recommended standard hours only. * Consult with affected neighbors about scheduling activities to minimize noise impacts. * Care should be taken to minimize noise from any refueling at night.
An example of a site layout showing how to reduce noise impacts is given in the figure below. Work practices used in this example are: * temporary noise barriers (hoarding) along site boundary * forward truck movements to avoid engaging reversing alarms * vehicle entrance, car park and site office located away from residences * limited number of mobile equipment operating near residences * Noisy fixed plant (generator) located as far as possible from residences.