Noise Study for EGC at Gas Sheikh Zowayed Metering and Regulation Station, Egypt

The purpose of this study is to investigate the noise impact from the operation of Gas Sheikh Zowayed Metering and Regulation Station at Sinai, Egypt. This document describes the noise sources and presents the results of the modelling applied to predict the noise impact on the surroundings during the maximum flow design conditions and emergency/worst case operations. The study will feed the design for provisions on noise protections required to meet the noise restrictions defined by the authorities and international occupational health regulations.

SCOPE OF WORK

The Noise Study presents the findings of a predictive noise modelling analysis of noise-emitting equipment’s during maximum flow operating conditions associated with the project. The study is performed to verify the sound pressure compliance for both workplace and environmental noise criteria. If any exceedance is found, suggestion of suitable mitigating measures either in design or management measures that are to be taken to meet the prescribed project and regulatory requirements.

The noise study has been developed through the following steps:

• Review of project documentation and definition of noise limits and base noise data for the calculations.
• Assess the impact of the equipment and plant noise in terms of
  • Occupational/ work area noise
  • Environmental / boundary noise.
• Development of a 3-D plant configuration including both obstacles and sources.
• Development of the numerical simulation.
• Simulation results analysis and definition of potential critical areas

NOISE STUDY METHODOLOGY INCLUDES

In order to estimate the operational noise level, the internationally recognised noise modelling software ‘SoundPLAN’ has been utilised.

The noise sources, identified for the metering station and described in section 3, are modelled in a noise prediction model. For the model the software SoundPlan 8.2 is used.

The noise modelling simulation of the project requires noise input data for all significantly noisy equipment in the project area identified during the preliminary noise study with following input:

• Maximum Allowable Sound Pressure Level (SPL) of noise source at a distance of 1 m;
• Source type estimation of the wavefront of the source, modelled as either a point or line source.

Noise sources are modelled in the following two types, depending upon the source geometry

• Point source: for sources of small dimension where no dimension prevails over another (e.g. small pumps and pressure control valves)
• Linear source: for sources where a dimension prevails over the others (e.g. filters, piping, etc.)

The following assumptions have been made for the modelling assessment, and wherever possible, a conservative approach has been taken:

• Equipment elevation and coordinated have been based on the engineering layout plot plans and site elevation sections provided.
• The main emission sources were assumed to be point or linear sources based on their nature. Sound waves from point sources travel in all directions (spherical propagation), and the sound energy decreases more rapidly under free field conditions than for linear or area sources.
• Structures apart was not included as sound barriers as a conservative measure.
• All sources were assumed to generate a mean frequency of 500 Hz, as a normal accepted in industrial applications as an accepted practice
• Configuration of packages have been based on the following operation criteria (however for maximum noise level, design conditions were used):

CONCLUSION OF THE STUDY

Based on the study it was found during the maximum flow scenario and maximum pressure the noise level does not exceed the contractual limit of 80 dBA and therefore there are no restricted areas during normal operating conditions. However, during emergency case scenario, the noise limit exceeds the 80 dBA during the operation of PSV and CRV as the noise level of respective valves are at 141 dBA.

The noise level at the edge of the skid under steady state operating conditions would range from 65 dB(A) to 70 dB(A) for maximum noise generating conditions (min pressure and maximum temperature) and 67 dBA to 71 dBA and during maximum design conditions (max pressure and temperature) 65 dB(A) and 70 dB(A).

During emergency scenario, it is estimated that the entire skid would experience noise level above 90 dBA. The contribution of the PSV and CRV reduces to 90 dBA at approximately 32 m from the base of skid and 70m respectively. Therefore, personnel entering the skid during the emergency scenario shall wear appropriate PPE (Personal protective equipment) for noise exposure such as earmuffs.

Based on the Noise Model results, the proposed metering skid, complies with the design conditions with the national & International limits, however, should the model input parameters change in the latter stages of the project, a model rerun would be required to assure the as built design compliance before commissioning & start-up.