Presentation: Possibilities for mitigating negative effects of noise and dust caused by extraction of sand, gravel and peat

1 6th International Conference on Sustainable Development in the 577 Minerals Industry, 30 June – 3 July 2013, Milos island, Greece Possibilities for mitigating negative effects of noise and dust caused by extraction of sand, gravel and peat Department of Mining, Tallinn University of Technology, Estonia ABSTRACT The Estonian legislation requires an environ-mental impact assessment prior to issuing a permit for extracting mineral resources. Extrac-tion of sand, gravel and peat involves dust and noise, their amount depending on the used tech-nology. Usually, the average noise level in the peat fields is 58.2 dB. The content of fine peat dust (<10 μm, PM10) usually ranges between 0.002 and 0.448 mg/m³ per 30 minutes during opera-tions (Orru et al., 2012b). Measurements in sand and gravel pits show that the content of fine dust (<10 μm, PM10) in the ambient air averages 0.011 mg/m³ per 60 minutes during pit operation. Modelling shows that noise in the sand and gravel pits dies away below 40 dB before reaching residential build-ings. An important alleviating measure is preserv-ing the surrounding forest. Precise models of the extent of dust and noise impact have to be com-piled. 1. INTRODUCTION In order to obtain a mining permit, an environ-mental impact assessment is needed, which should include an assessment of diffused noise and dust spread. In this article we observe the extent of diffusion of noise and dust from ex-ploited gravel and sand deposits to surrounding areas. Accordingly, we present and analyse po-tential mitigation measures. The study areas are Vinni and Tatramäe deposits in Estonia (Fig. 1). 2. MATERIAL AND METHODS Extraction of sand, gravel and peat involves dust and noise, their amount depending on the applied technology. Environmental impact as-sessment should include measuring, modelling and analysis of the extent of the diffusion of dust and noise in the environment. 2.1 Peat 2.1.1 Dust measurement The mainproportion ofpeat dust emerges dur-ingpeatproduction (milling andcollection). In order to find outthe exactamountofdust, peatdustmeasurementswere carried outon the San-gla and Varudipeat fields during the summer of 2011 (Lehtmets et al., 2012, Fig. 2). FineparticlePM10measurementswere car-riedout followingthe Ambient Air ProtectionAct (RT I, 31.12.2010, 31). FineparticlePM10was measured usingthe DustTrakIIHCdustanalyzer for 60 min at the 1.5 m level on a tri-pod. Figure 1: Locations of study areas. 578 6th International Conference on Sustainable Development in the Minerals Industry, 30 June – 3 July 2013, Milos island, Greece 2.1.2 Noise measurement Noiselevelswere measuredfollowing the noise measurement method (RTL 2002, 38, 511) and each point was measured with noisemeter TES 1254 for 60 minutes. 2.2 Sand and gravel Since the sand and gravel deposits are not being mined at the moment, modelling is needed to complete the environmental assessment. 2.2.1 Dust modelling Dust modelling was done with the CadnaA 4.1 + APL software and the following aspects were taken into consideration: fieldwork results, im-pactof forest, wind direction and speed (CAA), and size and location of spoils.Field measurements were used for creating a model assuming that in the active equipment in the pit include an excavator, a mobile crusher and a truck. Modelling resultsshow that already 300 metersaway the dust level will be reduced below the upper limit of allowed levels(Fig. 5). 2.2.2 Noise modelling Noise modelling was done with the CadnaA 4.1 software and the following aspects were taken in consideration: noise of the machinery, impactof forest, transport noise, and size and location of spoils. One excavator (80 dB), one mobile crusher (90 dB)andadump truck (70 dB) were placed in every pit in the model. Modelling resultsshow that thenoise from the pitdies away be-low 40dB before reaching inhabited areas (Fig. 3). The modelindicates thatpitnoise will be marginal. The mainsources of noiseare the highwayand other surroundingroads (Orru et al., 2012a). 3. RESULTS 3.1 Peat Measurements ofpeatdust(fineparticleslessthan10 micrometer, PM10) diffusing in the am-bient during anoperating period of30minutes gave results between 0.002 and 0.448mg/m³.Diffusion of dust is inversely proportional to the distance from the source and the spreading distance itself is in exponential dependence. Therefore, critical quantities of dust spread only close to the source.Based on the acquired knowledge, it is cer-tain that the annual amount ofpeatdust will not cause a health hazard to the surroundingpopula-tion.3.2 Noise Noise caused by peat transport from the peatproduction areas was measured during the summer of 2011. A peatproduction areahad the averagenoiselevel of40 dB.3.3 Sand and gravel 3.3.1 Vinni gravel pit - predicted cumulative noise together with a neighbouring race track Since the Vinni gravel pit is not being exploited, modelling was used to determine noise levels in Figure 2: Measuring peat dust in the Sangla peat field. Figure 3: The Vinni gravel pit and race track noise model.