the preliminary blasting plan, approximately 20 to 30 stemmed charges arranged may use additional impact avoidance techniques such use of blasting mats,.
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1 LAKE ERIE CONNECTOR BLASTING IMPACT ANAL YSIS IN US WATERS NOVEMBER 2015 INTRODUCTION Project Description ITC Lake Erie Connector LLC is proposing to construct and operate the Lake Erie Connector Project (Project), an approximately 116.5 km (72.4 mile) 1,000 megawatt (MW) +/ – 320 kilovolt (kV) high – voltage direct current (HVDC) bi – directional electric transmiss ion interconnection to transfer electricity between Canada and the United States (US) through a submarine transmission cable across Lake Erie (Figure 1). The HVDC transmission line consists of two transmission cables, one positively charged and the other n egatively charged, along with a fiber optic cable for communications between the converter stations located on either side of the border. In most areas the cables will be buried in the lakebed by a jet plow to protect the cables from damage due to shippi ng traffic, fishing activity, and ice scour. Typical burial depths in jettable material range from 3 to 10 ft (1 to 3 m). At the Erie, Pennsylvania (US) landfall, bedrock is either exposed or very close to the surface near shore, preventing cable burial v ia jet plow. Due to these geological constraints, a trench may need to be excavated by confined stemmed blasting in the bedrock (primarily shale) for approximately 1 mile (1.6 km) from the exit of the horizontal directional drilling (HDD) bore (approximat ely 2,000 ft [609.6 m] from the shoreline) to softer lake bed material where jet plow burial can be utilized. Stemmed charges will involve explosive materials placed into holes drilled into the substrate. Stemming is an approach that maximizes the pro pagation of shock forces into the substrate rather than into the water column, thereby increasing the efficiency of fracturing rock or consolidated materials while minimizing potential impacts to aquatic life and water quality. The trench would have a dept h of approximately 6 ft (1.8 m) to grade, which includes bedrock and any overlying mud and silt, and would have a width of approximately 4 ft (1.2 m). This method of blasting was selected to minimize potential impacts compared to detonations in open water , which would produce both higher amplitude and higher frequency shock waves than contained detonations. The preferred technique of stemming charges has been demonstrated to reduce pressures and lower aquatic organism mortality than the same explosive cha rge weight detonated in open water (Hempen et al. 2007, Nedwell and Thandavamorthy 1992). It is expected that a barge – mounted drill will drill 4 – inch (10 – cm) diameter blast holes to a depth of 4 ft (1.2 m) below the planned excavation grade. Additional b last holes will be required at similar intervals for the offshore sump pit s will be excavated in the rock at the exit of the HDD ( one bore for each HVDC cable and one bore for the fiber optic cable ) . Each of the three sump pit s will be approximately 20 x 10 x 7 feet (6.1 x 3.1 x 2.1 meters) . The holes will be packed with low – level Hydromite emulsion explosive, stemmed and detonated. The blasted rock will be removed by a barge – mounted excavator and side cast on the bottom. The trench will be bedded
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3 and backfilled with a sand and gravel mixture (originating from an on – land source). According to the preliminary blasting plan, approximately 20 to 30 stemmed charges arranged in a zig – zag drill pattern over a trench length of 30 to 40 ft (9 to 12 m) will constitute an individual charge or rate of 40 to 50 ft per day (12 to 15 m per day). Therefore completion of the blasting portion of the Project, assuming shots would occur on consecutive days, would require approximately 130 days between May and November. Review of Existing Studies and Research The detonation of explosives in or near water produces post – detonation compressive shock waves characterized by a rapid rise to a positive peak pressure followed by a rapid decay to below ambient hydrostatic pressure, creating a pressure deficit. The latter pressure deficit and the increase in peak particle velocity as a result of the d etonation can have an adverse impact on aquatic life, particularly in fish spawning areas (Wright and Hopky 1998). Depending on a number of variables, the detonation of explosives in or adjacent to fish habitat may cause disturbance, injury and/or death to fish, and/or the harmful alteration, disruption or destruction of their habitats (Wright and Hopky 1998). In some cases, blasting can cause mortality, physical injury, auditory tissue damage, permanent and temporary threshold shifts, behavioral changes, and decreased egg and larvae viability (Hastings and Popper 2005). The duration of temporary hearing loss varies de pending on the nature of the stimulus, but, by definition, there is generally recovery of full hearing over time (Popper and Hastings 2009). In general, the expected scales of potential impacts on local fish communities are contingent on multiple factor s, including the characteristics of the explosion (e.g., type and amount of explosive charge, location in the water column or substrate, depth, substrate type) and morphology (e.g., presence/absence of swim bladder, size) and behavior (e.g., orientation to substrate) of the species exposed to blast forces. Factors that govern the scales of impact are reviewed in Continental Shelf Associates (2004) and Popper et al. (2014). Although the physical aspects of underwater explosions are relatively well understoo d and predictable, considerable uncertainty still surrounds the responses and meaningful thresholds of exposure for a large majority of fish species and life history stages. Popper et al. (2014) recommended exposure guidelines based on the existing state of knowledge relevant to sound pressure and particle motion. Using conservative estimates for juvenile and adult fishes in three groups (i.e. fishes with no swim bladder, fishes with swim bladders but no involvement in hearing, and fishes with swim bladde rs involved in hearing) based on Hubbs and Rechnitzer (1952) experimental data, Popper et al. (2014) identified 229 to 234 dB peak values referenced to 1 microPascal as exposure thresholds that could cause immediate or delayed mortality. Given the lack of quantitative data on thresholds for non – permanent injury, temporary threshold shifts (TTS) which are short or long term changes in hearing capability, and behavioral responses (i.e. avoidance, change in feeding) , Popper et al. (2014) relied on relative probabilities of impact (high, moderate, low) at distances from the source that are near (10s of meters), intermediate (100s of meters), and far (greater than 1,000 meters) . The probability of non – lethal responses would be low at far field distances for al l fish species. However, according to the Popper et al
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4 (2014) predictions, fishes with swim bladders involved in hearing would experience high probabilities of all three categories of non – lethal impact at intermediate distances. At intermediate distances fishes with swim bladders that are not involved with hearing would experience high probabilities of recoverable injuries and behavioral responses, but moderate probabilities of TTS. Fishes lacking swim bladders would experience low probabilities of recov erable injuries and moderate probabilities of TTS and behavioral responses at intermediate distances (Popper et al. 2014). Predicting non – lethal responses is more difficult owing to the diversity of fish species that might be present in the Project area. No evidence of TTS in fishes as a response to explosions has been documented, although the frequency of explosion events may come into play. Likewise, behavioral responses have not been documented for free swimming fishes near underwater explosions . Startle reactions, which are short in duration, would be the most probable response (Popper et al. 2014). The above thresholds pertain to juvenile and adult stages of fishes. With respect to egg and larval stages, relatively little research has been conducted. Criteria applied by the Canadian government are based on findings that developing embryos could be damaged by shock waves propagating through the water column or through the substrate. In these cases particle motion is presumed to be the under lying cause of impact rather than sound pressure. Consequently Popper et al. (2014) refer to Wright and Hopky (1998) as the basis for setting 13 mm/s (0.51 in/s) as the maximum allowable peak particle velocity in a spawning habitat during any period when eggs are present. Few previous studies of effects of underwater explosions have been performed in the Great Lakes region. Ferguson (1961) subjected caged yellow perch ( Perca flavescens ) to underwater blast pressures produced by charges of nitrone, nitrone primer, black powder, and squib cap near Wheatley, Ontario, Canada. All explosions occurred in 5 to 10 ft (1.5 to 3.1 m) of water at locations where bottom depths ranged up to 58 ft (17.7 m). Cages were placed at a depth of 10 ft (3.1 m) or rest ed on the bottom at distances from 25 to 207 ft (7.6 to 63.1 m). Black powder charges produced few injuries among any caged fish, and then only if a nitrone primer was used to detonate the charge. Nitrone primer detonated alone produced mortalities in al most all caged perch at 50 ft (15.2 m) and injured many at 200 ft (61.0 m). A 20 lb nitrone charge produced mortalities in almost all perch out to 200 ft (61.0 m). It is important to note that mid – water explosions are known to be much more damaging than stemmed charges detonated in the substrate. Also, yellow perch have well – developed swim bladders, rendering them sensitive to pressure changes, and are not representative of entire fish assemblages (Ferguson 1961), such as the range of fish species found in the Great Lakes. The reduced impacts of stemmed charge/subterranean explosions versus mid – water explosions were illustrated by Traxler et al. (1992), who reported no mortalities or observable injuries among largemouth bass ( Micropterus salmoides ), blue gills ( Lepomis macrochirus ), and channel catfish ( Ictalurus punctatus ) held in cages placed directly above and at distances between 7.6 and 91.4 m (25 and 300 ft) from shot holes containing 4.5 and 9.1 kg of dynamite. Their experiments were conducted in a freshwater reservoir in Texas.
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5 Teleki and Chamberlain (1978) monitored acute effects of blasting on fishes during deepening on a site in near – shore waters at Nanticoke, Long Point Bay, Lake Erie. Their experimental design involved deployment of cage d specimens of 13 locally caught fish species at predetermined distances as far as 185 m (607 ft) from the explosion. Post – explosion monitoring included collection of free swimming fishes for a period of 30 minutes following the blast. Peak pressures at predetermined distances and depths were recorded over the course of 201 blasts. Explosions occurred in three types to fracture the limestone bedrock below overlying glacial till harges to crush production blasts. Immediately after each explosion fishes were removed from the cages and autopsied for evidence of barotrauma or other injuries. Pe ak pressures associated with the blasts were influenced by the type of substrate and the depth of the drilled hole containing the charge. Among caged fishes pumpkinseed ( Lepomis gibbosus ), crappie ( Pomoxis sp.), and white bass ( Morone chrysops ) were most sensitive to pressure changes, whereas rainbow trout ( Oncorhynchus mykiss ), yellow bullhead ( Ameiurus natalis ), and white sucker ( Catostomus commersonii ) were least sensitive. Other species exposed in cages were gizzard shad ( Dorosoma cepedianum ), yellow perch ( P. flavescens ), smallmouth bass ( Micropterus dolomieu ), rock bass ( Ambloplites rupetris ), freshwater drum ( Aplodinotus grunniens ), quillback ( Carpiodes cyprinus ), and common carp ( Cyprinus carpio ). Additional species occurred in the post – blast free swimming fish catches. Emerald shiners ( Notropis atherinoides ) occurred commonly among visibly injured fishes at the surface, with trout – perch ( Percopsis omiscomaycus ) and rainbow smelt injured less frequently. In sub – surface and bottom towed nets higher mortalities were observed in the upper stratum (< 4 m, 13.1 ft), which consisted primarily of alewives ( Alosa pseudoharengus ) and emerald shiners. Among the caged fishes the minimum peak pressure that produced immediate or delayed mortalities varied great ly between species, generally between 30 and 85 kPa (Teleki and Chamberlain 1978). The above field studies are relevant to juvenile and adult fishes, but concerns have also been expressed by regulatory agencies for protection of eggs, particularly those t hat develop while in intimate contact with the substrate. In theory, vibratory forces expressed as particle velocity in addition to pressure changes could detrimentally affect embryonic development and survival. In two separate studies Faulkner et al. (2 006, 2008) examined the fates of lake trout ( Salvelinus namaycush ) and rainbow trout ( Oncorhynchus mykiss ) eggs exposed to blast forces. Lake trout eggs were exposed to blasts in an open water mining pit, whereas rainbow trout eggs were exposed to simulat ed blast parameters under controlled laboratory conditions. Measured peak particle velocities at the lake trout egg exposure site reached 28.5 mm/s (1.1 in/s), more than twice the established Canadian protection standard of 13 mm/sec (0.5 in/s). In terms of survival, when exposed lake trout eggs were compared to eggs at a reference site, no significant effects were observed. In the laboratory experiments increased mortality rates were found only when rainbow trout eggs were exposed to particle velocities greater than 132.3 mm/s (5.2 in/s) (Faulkner et al. 2006, 2008). Another commonly used blasting assessment guidance document was developed by Baker (2008) which discusses recommendations for assessing impacts to protected species (threatened and endangered species and marine mammals), and mitigation planning for the use of explosives during the construction, operation, maintenance, or decommissioning phases of a project. The PAGE - 6 ============ 6 Baker method used to calculate setback distance varies based on the bla sting plan type (e.g. confined, unconfined). As noted in the guidance document, the method is believed to be highly conservative in estimating zones of influence for protected species because it is intended to protect more sensitive marine species such as marine mammals in addition to fish. Therefore, as discussed in the Methods Section below, blasting standards established by the Alaska Department of Fish and Game (ADF&G 1991) and Timothy (2013) for Alaskan waters represent more appropriate and the mos t recent guidance available for the present Project scenario. In Pennsylvania waters of Lake Erie, three fish species merit special consideration due to their status as state protected species: lake sturgeon ( Acipenser fulvescens ), eastern sand darter ( Ammocrypta pellucida ), and cisco ( Coregonus artedi ). Lake sturgeon spawn during April to June over gravel shoals and along rocky shorelines of lakes in water depths of 1 to 15 ft (PNHP 2015, GLIMDS 2015, Scott and Crossman 1998). Most eastern sand darter s spawn during June and July (Crisewell 2013). They have not been observed to spawning in the wild (Adams and Burr 1994), but are reported to occur in clean sandy shoals along lakeshores (Criswell 2013), although this species has also been found in depths of 15 m to 20 m and greater in Lake Erie ( Grandmaison et al. 2004, PFBC unpublished) . Cisco spawn in late fall to early winter (ODNR 2014) and hatch soon after ice out (MDNR 2015). Spawning occurs in shallow water (1 - 3 meters) over gravel or stony subs trate, but also may occur pelagically in midwater (Nature Serve 2015, Pritchard 1931, Smith 1956, Becker 1983, Scott and Crossman 1998). A search of the scientific literature found no data on blasting effects thresholds for these species. For this P roject, the potential for impacts to occur along the proposed underwater cable route was assessed by estimating the extent and duration of the sound pressure level and shock wave associated with the proposed blasting, and comparing these estimates to publi shed guidelines and effects thresholds for fish species that have published criteria. The following sections provide the methods and the assessment. METHODS Rationale for and Calculation of Setback Distance In order to assess the scales of potential impact of blasting on aquatic resources, one must determine the probabilities of a blast producing forces that exceed thresholds of detrimental effect and then relate the thresholds to meaningful levels of severity. That is, the calculation of setback dis tance approach evaluates exposures of fishes to blast - induced forces that could potentially cause mortality or sublethal responses. Therefore, an assessment must consider the magnitude or intensity of exposure with respect to distance from the blast. For example, as margin of safety for permitting projects in the vicinity of known fish spawning habitat; restricting blasts to locations at distances greater than what would induce detrimental impacts would serve as an effective mitigation measure. In cases such as the present Project the near shore zone is used by multiple species for spawning, nursery and foraging habitat, the assumption can therefore be made that bl asting will occur in proximity to one or more species. PAGE - 8 ============ 8 Values for D r and C r for rock substrate are 165 lbs /ft 3 and 15,000 ft/s as given in ADF&G 1991. Eqn 2. Equation 2 describes the transfer of shock pressure from the substrate to the water: where: P w = pressure (psi) in water P r = pressure (psi) in substrate By setting the value of P w to the criteria pressure levels from Table 1 the corresponding value for P r can be computed. Eqn 3. Equation 3 describes the relation between the peak particle velocity (V r ) and the pressure, density and compressional wave velocity in the su bstrate: Eqn 4. Equation 4 represents the scaled distance relation and is used to equate the peak particle velocity to charge weight and distance: where: V r = peak particle velocity in in/s R = distance to the detonation point in ft W = charge weight per delay in lbs RESULTS The resulting setback distance using the proposed charge weights, guidelines from Table 1 and equations 1 through 4 are summarized in Table 2 and shown graphically in Figures 2 and 3. Table 2. Setback Distance for Guideline Criteria, Timothy 2013 Criteria Setback Distance Overpressure (fish) 63.3 ft Peak Particle Velocity (eggs) 53.1 ft PAGE - 11 ============ 11 ASSESSMENT In the area immediately adjacent to the shoreline out to approximately 2,000 ft (609m), HDD will be used to avoid important spawning habitat for the Lake Erie fish community. Blasting is being proposed in Lake Erie only for distances of approximately one mile beyond the lakeward extent of HDD where bedrock is either exposed or very close to the surface, before the bedrock transitions to silt amenably to use of jet plow cable installation. Impact Assessment Based on the review of existing literature an d studies discussed above, the assumptions used to calculate the setback distance for peak particle velocity and pressure for this Project are conservative. Applying the above approach to estimating potential impacts on fish takes into consideration the f act that high risk of lethal or permanent injury would be confined to the immediate vicinity of the explosion where compressive forces of the shock wave predominate. Injuries at greater distances are generally caused by negative pressures associated with overshoot surface (Popper et al. 2014). The 229 to 234 dB re 1 microPascal threshold for mortality recommended by Popper et al. (2014) corresponds to 40 to 70 psi or 276 to 482 kPa. Thus the overpressure criteria identified in Table 1 (7.3 psi and 100 kPa) are very conservative. The potential for lethal impacts would be expected to occur in a very small footprint (less than 63.3 ft (19.2m) from the blast location) surrounding an individual blast. A single blast per 24 hr period would not be expected to induce strong avoidance responses . Fo llowing startle responses, which might last only for seconds to minutes, fishes would return to the general vicinity of th e blast. Blasting events will not be long in duration with repeated exposures sustained over periods as long as hours to days. Repetitive detonations over relatively short periods of time , which will not occur for this project, w ould have a greater risk of TTS and behavior responses. However, for this project we do not expect this to be the case and anticipate a lower likelihood of physiological impact or prolonged behavioral response due to the blasting plan. Blasting can cause mortality, physical injury, auditory tissue damage, permanent and temporary threshold shifts, behavioral changes, and decreased egg and larvae viability. However, based on the setback calculation for this Project, the extent of direct i mpacts and mortality is limited to 63.3ft (19.2m). Peak pressures and particle velocities decrease with distance from the detonation and therefore potential impacts are reduced as well. A number of commercially, recreationally, or ecologically importan t fish species spawn in shallow Lake Erie habitats in spring and early summer. For example, yellow perch, white bass, walleye ( Sander vitreus ), alewives, rainbow smelt and spottail shiner ( Notropis hudsonius ) all spawn over sandy, gravel, or rocky substra tes in March through April and into M ay (Daiber 1953, Bodola 1966, Leach and Nepszy 1976, Madenjian et al. 1996, Roseman et al. 1996). In addition, lake sturgeon, which is provided protected status, spawns primarily in tributaries but potentially also ove r gravel shoals and rocky shorelines in April through early June when water temperatures are between 55 and 64 o F (GLIMDS 2015, Dick et al. 2006, Scott and Crossman 145 KB – 17 Pages