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Home My WebLink About1.05 EnvironmentalF P ACOUSTICAL CONSULTANTS INC. Date: March 20, 2008 To: Mr. Preston Nelson EnCana Oil & Gas (USA) Inc. 2717 County Road 215 Parachute, Colorado 81635 From: Tim Simmons, Ph.D. HFP Acoustical Consultants Inc. Re: Pre- Construction Sound Level Prediction Computer Noise Model for COGCC Compliance South Middle Fork Compressor Station Garfield County, Colorado HFP File No. 6466 -1 TECHNICAL MEMORANDUM #6466 -1A -I A three - dimensional computer noise model was created for the proposed EnCana South Middle Fork Compressor Station. The design goal is that the total compressor station sound level contribution be less than or equal to 50 dB(A) at a distance of 350 feet from noise sources or at the property line, whichever distance is greater. This is in accordance with the Colorado Oil and Gas Conservation Commission ( COGCC) nighttime noise limit for a neighboring residential /agricultural /rural zone. The model was developed using Cadna/A, version 3.7.123, a commercial noise modeling package developed by DataKustik GmbH. The software takes into account spreading losses, ground and atmospheric effects, shielding from barriers and buildings, and reflections from surfaces. The computer noise model calculations are based on "ISO 9613 -2: Acoustics — Attenuation of sound during propagation outdoors." Digital terrain elevation data, derived from USGS data was downloaded and incorporated in the computer noise model. The facility is currently in preliminary design stage, so specific equipment has not been selected. The analysis is based on currently available equipment lists and drawings. Scheduled equipment includes: • Eight 7500 hp electric -drive compressors • Eight 156 -3 -Z air coolers • Two CAT 3516 Gensets • Three CAT 3616 -drive compressors (temporary units) • Three 144 -2 -Z air coolers (temporary units) 6001 Savoy Drive, Suite 115 Phone: 713.789.9400 #1 140, 10201 Southport Road S.W. Phone: 403.259.6600 Houston, Texas 77036 Fax: 713.789.5493 Calgary, Alberta. Canada T2W 4X9 Fax: 403.259.6611 March 20, 2008 EnCana Oil & Gas (USA) Inc. South Middle Fork CS Technical Memorandum 6466 -1A -1 HFP File 6466 -1 Page 2 The attached Figure 1 shows the compressor station site property line and equipment layout. The attached Figure 2 shows the predicted A- weighted sound level contributions from the compressor station at several locations along the property line. The predicted contributions range from 36.0 dB(A) at the south to 46.5 dB(A) at a location which is 350 feet south/southeast of the air coolers for Compressor Building 1. This location falls just outside the station property line. These levels are based on the noise control measures listed in Table 1. All compression and genset equipment is modeled as enclosed in acoustically treated buildings, in order to meet the noise goal. The air coolers also will require noise control treatments. Figure 3 (on the following page) shows a 3 -D rendering of the compressor station and vicinity. Table 1: South Middle Fork CS - PRELIMINARY DESIGN Noise Source Treatment Description Compressor Building_l Walls and Roof Minimum STC -45 absorptive acoustical building Ventilation Wall Inlets Openings High Performance Acoustical Louver Ventilation Roof Exhaust Openings Ventilation Silencer, 3' long Personnel Doors Standard STC -32 Man Door Equipment Doors STC -24 Roll Door Coolers: 156 -3 -Z Required DIL overall 26 dB reduction Compressor Building 2 Walls and Roof Minimum STC -45 absorptive acoustical building Ventilation Wall Inlets Openings High Performance Acoustical Louver Ventilation Roof Exhaust Openings Ventilation Silencer, 3' long Personnel Doors Standard STC -32 Man Door Equipment Doors Double Roll Door CAT 3616 Exhaust GT 6100 Series High Performance Muffler Coolers: 144 -2 -Z Required DIL overall 26 dB reduction Generator Building Walls and Roof Minimum STC -45 absorptive acoustical building Ventilation Wall Inlets Openings Enviro Noise Control Air Inlet Hood Ventilation Roof Exhaust Openings Ventilation Silencer, 3' long Personnel Doors Standard STC -32 Man Door Equipment Doors Double Roll Door H F P ACOUSTICAL CONSULTANTS March 20, 2008 EnCana Oil & Gas (USA) Inc. South Middle Fork CS Technical Memorandum 6466 -1A -1 HFP File 6466 -1 Page 3 Figure 3: 3 -1) rendering of the proposed South Middle Fork Compressor Station looking from the southeast. This completes Technical Memorandum 6466 -1A -1. Please call if you have any questions or comments. Respectfully submitted, HFP ACOUSTICAL CONSULTANTS INC. )'j . Tim Simmons, Ph.D. Senior Project Consultant Attachments: Figures 1 and 2 H F P ACOUSTICAL CONSULTANTS HIIIlIliIIIIIIIIIIIIIIHIlIl