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HomeMy WebLinkAbout05 - Port Burwell Dredge Monitoring Study PORT BURWELL HARBOUR DREDGE MONITORING STUDY Interim Report Prepared for: Village of Port Burwell P.O. Box 10, Port Burwell, On NOJ 1 TO Prepared by: Aquafor Beech Limited July 1996 Ref. No. 67372.30 EXECUTIVE SUMMARY Introduction The Village of Port Burwell is located on the north shore of Lake Erie approximately 40 km west of the Long Point Peninsula. Port Burwell Harbour is situated at the mouth of Big Otter Creek which flows through the Village of Port Burwell. The harbour services pleasure craft during the ' !' e summer boating season as well as commercial fishing and diving activity. (" b`) Big Otter Creek transports a high sediment load to Lake Erie which historically has resulted in the requirement to dredge material both from the Inner Harbour and on an approach path to the harbour to enable navigation. To provide an intuitive understanding of the local system, the following information is provided below Sediment Loadings • Big Otter Creek annually discharges approximately 140,000 tonnes of sediment to Lake Erie; • the volume of material to be dredged from within the Inner Harbour has been estimated to be approximately 1,500 to 3,500 tonnes, or 1.0 -2.5 % of the annual load; • daily loadings from Big Otter Creek exceed 1,000 tonnes roughly 25 times per year; Sediment Concentrations • maximum recorded suspended sediment concentration in Big Otter Creek is 5,750 mg/L; • suspended sediment concentrations exceed 200 mg/L roughly 75 times per year. Concerns were raised by regulatory authorities regarding the effect of plough dredging and prop- washing of sediments within the Port Burwell Inner Harbour. Subsequent to discussions with OMOEE, OMNR, Canadian Coast Guard, LPRCA,and the Village of Port Burwell,this study was commissioned to develop and implement a monitoring program to provide information on the effects of the experimental process of plough dredging. The objective of the monitoring program was to determine the appropriateness of the plough dredging and prop-washing technique for navigational dredging of Port Burwell Harbour. Monitoring Program The monitoring program that was developed consisted of four phases. These four phases are briefly explained below: Phase 1 - Completion of an aquatic habitat assessment. This was intended to identify sensitive aquatic habitats that may be adjacent to the proposed dredging site; Phase 2 - On-site monitoring consisting of turbidity, dissolved oxygen, and temperature measurements. This was intended to provide real time estimates of the impact of the dredging process; Phase 3 - Laboratory analysis of total suspended solids, bacteria, and particle size distribution samples collected during the dredging period. This was intended to provide additional information not readily available during the course of the monitoring program; Phase 4 - Multiple bathymetric surveys completed over the summer and fall of 1996, and the spring of 1997. The purpose of this component is to evaluate the rate of sediment deposition and bed movement within Port Burwell Harbour. Results A brief summary of the key results and observations recorded during phases 1, 2, and 3 of the monitoring program are presented below: The aquatic habitat assessment indicated that habitats are marginal throughout the local area, offering limited nursery habitat for some warmwater species or migration habitat. The proposed dredging and disposal activities represent a short term disruption of natural processes and represent only a minor disruption in habitat use by fish. The dredging activities completed on the Port Burwell Inner and Outer Harbours were ii completed over the period spanning June 4-6, 1996. The majority of the time expended by the dredging contractor was spent prop-washing an approach path to the Inner Harbour through the Outer Harbour. Only four hours on June 5, 1996 was spent dredging a path through the Inner Harbour. • Visual observations, sample data collected during the study, and historical data indicate that natural resuspension has a more significant effect on the suspended sediment concentration in the water column than the dredging activities completed. Provided below are key points which support the aforementioned statement: • the highest turbidity measurements at the control monitoring sites (site 3 - 183 NTU, site 4-231 NTU,site 5 - 145 NTU)were collected on days when no dredging occurred; ► historical turbidity measurements at the east and west beaches are significantly higher than any values measured during this study(east beach- 820 NTU,west beach->1000 NTU); ► TSS concentrations on days when no dredging occurred were either greater or approximately equal to the values measured on days when dredging did occur; ► It should be noted that the natural resuspension observed was only due to wind and wave action during dry weather periods. Typically,wet weather conditions would cause even more resuspension as the increased natural sediment load from Big Otter Creek would be added to the impact of stronger winds and higher waves from Lake Erie. ► At no time during the monitoring program did the measured turbidity values exceed the predetermined criteria of double the background concentration. ▪ Collection of bacteria samples and dissolved oxygen measurements indicated the dredging activities had no effect on the background concentration of either parameter. • Comparison of the particle size distribution in the Inner Harbour with the natural background distribution flowing down Big Otter Creek indicates resuspension of the Inner Harbour sediments will not result in a higher proportional loading of silty clay material than the background levels. iii Conclusions Review of the results from the current study and historical data indicate the combined prop-washing and plough dredging completed during the course of the three day period had no additional impact on the surrounding area. The effects of frequently occurring natural processes far exceed the worst case conditions that can be generated by dredging activities. Due to the overriding effects of natural processes, dredging activities will not expose the local environment to an unusual amount of stress at any time throughout the year. However, if itA.° is known early in the year that the harbour will require dredging for navigation during the course of the year, it is recommended that future dredging be carried out during the spring months. This is the time of year when the natural sediment loading is highest, and the likelihood of elevated oN concentrations will allow even the negligible effects of the dredging activities to be assimilated. The prop-washing and plough technique is both applicable and acceptable for the dredging of the Port Burwell Harbour due to the naturally high sediment concentrations and shallow depths which exist at this location. To determine the acceptability of this technique at other locations would require a procedure similar to that completed for this study. The prop-washing 1 ploughing technique may not be applicable for sites with lower naturally occurring sediment concentrations, nearby sensitive aquatic habitat, or deeper channels. iv TABLE OF CONTENTS Page 1.0 BACKGROUND 1 2.0 MONITORING PLAN 3 3.0 AQUATIC COMMUNITY ASSESSMENT 6 4.0 CHRONOLOGICAL HISTORY OF DREDGING PERFORMED 10 5.0 MONITORING PROGRAM RESULTS 12 6.0 RESULTS OF BATHYMETRIC SURVEY 17 7.0 CONCLUSIONS AND RECOMMENDATIONS 18 APPENDIX A : MONITORING RESULTS 1.0 BACKGROUND The Village of Port Burwell is located on the north shore of Lake Erie approximately 40 km west of the Long Point Peninsula. Port Burwell Harbour is situated at the mouth of Big Otter Creek which flows through the Village of Port Burwell. The harbour services pleasure craft during the summer boating season as well as commercial fishing and diving activity. The commercial diving industry is primarily associated with the maintenance of a large network of natural gas wells located offshore all along the north side of Lake Erie. Figure 1 illustrates the location of Big Otter Creek relative to the Village of Port Burwell and Lake Erie. Big Otter Creek transports a high sediment load to Lake Erie which historically has resulted in the requirement to dredge material both from the Inner Harbour and on an approach path to the harbour to enable navigation. Concerns were raised by regulatory authorities regarding the effect of plough dredging and prop-washing of sediments within the Port Burwell Inner Harbour. Subsequent to discussions with OMOEE, OMNR, Canadian Coast Guard, LPRCA, and the Village of Port Burwell,this study was commissioned to develop and implement a monitoring program to provide information on the effects of the experimental process of plough dredging. The objective of the monitoring program was to determine the appropriateness of the plough dredging and prop-washing technique for navigational dredging of Port Burwell Harbour. This interim report is intended to address the short term impacts of the dredging completed. A final report will be submitted when the bathymetric monitoring has been completed. Background information regarding the magnitude of the sediment load from Big Otter Creek to Lake Erie is presented in Section 1.1. The development of the monitoring program implemented during the study is presented in Section 2.0. The results of the monitoring program are presented in Sections 3 through 6. The conclusions and recommendations drawn from the information collected during the monitoring program are presented in Section 7. Port Burwell Dredge Monitoring Study 1 Tiri ,V 1� �` – est © -•r:A 38 ® Kiritora' vq•jik Em n Q � �IA.H x !" 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''41',;x,, ..'4.y�_ i14, u.:„,a�-z .. .w..� -..-,e...-Viii! • ,,. •,e . ._4 K EY MAP FIGURE 1 N.T.S. 1 I 1..1 Big Otter Creek Sediment Load The natural sediment load being transported by Big Otter Creek has been examined to gain perspective on the quantity of sediment to be dredged relative to the normal background levels. Historical suspended sediment concentration and loading information was obtained for Big Otter Creek from the Water Survey of Canada(WSC) station upstream at Calton. The data obtained for the period between 1976 and 1993 indicated the following: Loadings • long term mean daily load of 410 tonnes; • maximum daily loading of 31,000 tonnes; • daily loadings of z 1000 tonnes occur roughly 25 times per year; • long term mean annual load of 140,000 tonnes; Concentrations • maximum suspended solids concentration of 5,750 mg/L; • suspended solids concentration of z 200 mg/L occur roughly 75 times per year. The higher suspended sediment concentrations and loadings typically occur during the spring months of March- June. However, sporadic high concentrations of suspended sediments are not unusual throughout the remainder of the year. Review of available sediment distribution data from the WSC station indicates that approximately 25-30% of the suspended sediment being transported down Big Otter Creek is sand while the remaining 70-75%is composed of fine silts and clays. This would suggest that the majority of the TSS loading from Big Otter Creek would remain in suspension longer and hence flow out to Lake Erie. The component of the TSS loading most likely to settle out in the harbour would be the heavier sands and not the finer material. Port Burwell Dredge Monitoring Study 2 2.0 DEVELOPMENT OF MONITORING PLAN Numerous techniques have been developed to dredge sediments from the bottom of a creek or a lake. The amount of resuspension associated with each method is variable and certain techniques tend to minimize the amount of resuspension while others are more disruptive. Prop-washing is one of the most disruptive techniques currently used, as the method is intended to hydraulically push the material away from the boat propeller(prop). Though the majority of the material is simply pushed along the bottom, a fraction of the sediments is inherently resuspended which results in elevated water column TSS concentrations. An experimental method of using a large plow attached to the stern of a tugboat was suggested for use in the dredging process. Due to the close proximity of the plough to the prop, a significant amount of material is resuspended with this method. However, it was expected that less material would be resuspended than solely using prop-washing. In addition, the plough methodology provides better control of the accuracy of the depth of dredging. The following monitoring program was developed for the purpose of examining the overall appropriateness of using the plough technique within the Inner Harbour. The Inner Harbour is defined as the section of Big Otter Creek upstream of the south tip of the east pier. Prior approval of the prop-washing technique for the Outer Harbour was granted and hence did not require monitoring. However, for the purposes of this study these activities were also monitored. The monitoring program developed consisted of four phases. Phase 1 involved evaluation of local sensitive aquatic habitats as no background information was available. A field inspection of the Port Burwell area was completed by a qualified aquatic biologist and by the Ministry of Natural Resources. The results of this inspection were subsequently used to establish the monitoring locations to be used for Phases 2 and 3, and are presented in Section 3.0. Port Burwell Dredge Monitoring Study 3 Phase 2 involved onsite monitoring of the impacts due to the dredging procedures. This involved collection and analysis of turbidity, dissolved oxygen, and temperature at various locations. Total suspended solids samples were also collected at the monitoring sites. Six sites were identified as primary locations for monitoring of turbidity and total suspended solids. These six sites are shown on Figure 2 and are briefly described below. Site I - Big Otter Creek upstream of the proposed dredging; Site 2 - South tip of the east pier; Site 3 - Port Burwell east beach, approximately 50m from shore; Site 4 - Port Burwell east beach, approximately 150m from shore; Site 5 - South tip of breakwater; Site 6 - Port Burwell west beach, on the west side of the breakwall. Additional sites were also sampled directly adjacent to the dredge boat while it was prop-washing in the outer harbour to obtain worst case resuspension values. These sites are referred to as 2A, 2B, 2C,2D,and 2E, and are show on Figure 2. Additional turbidity samples were collected around the east pier(Sites T1-T5)while the dredging of the Inner Harbour was ongoing. Bacteria samples were also collected from various locations while the dredging was ongoing. Water column samples were taken to characterize the concentration of bacteria present both adjacent to the dredge boat and at more distant locations. Bulk sediment samples were collected in the inner and outer harbours to enable particle size analysis at the two locations. This was intended to determine the proportion of fine material to coarse material present in both locations. The intent of the onsite monitoring was to provide the ability to evaluate the impact of the dredging while it was ongoing. Turbidity was selected to be the decision parameter used onsite for evaluation of the impact of the dredging as portable turbidity meters exist, while laboratory analysis is required Port Burwell Dredge Monitoring Study 4 A VILLAGEOF PORT BURWELL _I If----) gi i I- Ir o j0 BiG 1 .:::,,:.. 1 ":. cilillIk GREEK I n i LAKE ERIE - T3 LEGEND ; ng ® Baseline Monitoring Sites ®Ui� _ 11:: 2b] Additional T41 n Monitoring Sites El a IZU 2c Particle Size t A\ Analysis Sample Collection Points Approximate Ei Extent of Dredging Aquafor Beech Limited COMIRMICHMMMW VILLAGE OF PORT BURWELL MONITORING LOCATIONS EXTENT OF BREAKWALL i FIGURE 2 Oso 0 so 100 100 200 • SCALE 1:7500 to assess suspended solids concentrations. Threshold values equal to twice the background turbidity levels was chosen as the cutoff for temporarily shutting down the dredging activities. The dredging would then be restarted once suitable conditions were present. Phase 3 involved laboratory analysis of samples collected during Phase 2. This included total suspended solids samples,bacteria(E. Cob) samples,and particle size distribution tests. The results of these tests would then be evaluated after the dredging had been completed to assess the impact of the dredging activities. Phase 4 consisted of bathymetric monitoring to estimate the extent of the dredging completed, and the rate at which the dredged area will fill in due to subsequent settling of suspended material. A total station survey was completed shortly after the dredging activities were completed. Subsequent monthly to bi-monthly surveys will be completed to evaluate the deposition rate. Port Burwell Dredge Monitoring Study 5 3.0 AQUATIC COMMUNITY ASSESSMENT The mouth of Big Otter Creek has been altered, historically, by means of dredging, filling of the estuary, and armouring portions of the riverbanks with steel sheet piling, concrete, boulders, and dock structures. In order to protect the created harbour, concrete and sheet pile jetties have been constructed out into the nearshore of Lake Erie on either side of the river mouth. The jetty on the west side extends furthest offshore. The harbour consists of two areas: an Inner Harbour area which provides dockage for small and large vessels, and an Outer Harbour area which provides access to the Inner Harbour and the mouth of Big Otter Creek. Big Otter Creek,upstream of the inner harbour is about 25 m wide with low,vegetated banks and a fairly narrow floodplain. The river gradient is very shallow, in the order of 1%. Dredging activities in 1996 were undertaken by plough dredge, generally confined to the Inner Harbour,and by"prop washing"which was generally confined to the Outer Harbour. Material from the Inner Harbour was distributed outside the approach path in the Outer Harbour. On either side of the harbour entrance, the Lake Erie shoreline consists of fine textured beaches. The western beach is backed by dunes and low bluffs; the eastern beach is backed by low to moderate bluffs. The shore gradient of these beaches is quite shallow, about 2%. The discharge from Big Otter Creek is highly turbid and brownish in colour from sediments generated from the upstream drainage area. The nearshore of Lake Erie is also highly turbid, but more greyish in colour,as a result of erosion and transport of lake generated sediments. The plume from the harbour mixes gradually with the lake waters and the size and spatial distribution of the plume is influenced by wave action and river discharges. As a result,the plume from the river can impact large areas in the vicinity of the harbour. Although the river water and lake water differ in colour, they both represent highly turbid conditions for fish. Port Burwell Dredge Monitoring Study 6 Aquatic habitats in each of the following areas were inventoried during site visits in late May: • Big Otter Creek, upstream of the inner harbour • the inner harbour • the outer harbour • the eastern beach • the western beach Information related to the variety of species present within the study area was supplied by Ministry of Natural Resources personnel. Receipt of the information presented below is gratefully acknowledged by Aquafor Beech Limited. Big Otter Creek: Upstream of the Inner Harbour, the river is highly turbid as a result of sediment loads from within the watershed. Substrates consisted of medium to coarse sand with a trace of silt in the main channel with finer, more organic silty clay material near shore. Water depths were 1 - 2 m and the channel was generally "U" shaped. The river banks were coated with fine sediment from previous high flows and there was some evidence of bank slumping. Some rooted aquatic plants were growing along the river edge,however,high turbidity likely limits any extensive growth. The habitat conditions are considered to be poor to marginal as nursery habitat for warmwater fish because of the limited macrophyte growth and high turbidity. The area provides migratory habitat for lake species migrating upstream, although there are no suitable spawning areas for warm or cold water fish for some distance upstream. The following species were captured by seine: juvenile crappie (1),johnny darter (2), creek chub (1), spottail shiner (1), emerald shiner (3), bluntnose minnow(2), fathead minnow (1) and white sucker(1). Inner Harbour: the water is highly turbid and substrates are similar to the area upstream, although there is more silt mixed in with the medium sand. Water depths are slightly greater as a result of Port Burwell Dredge Monitoring Study 7 past dredging activity. The river banks have been altered by filling, sheetpiling and armouring with boulders/concrete,and dock/launching facilities. No macrophyte growth was apparent and the river edges were steeper, but substrates at the river margin were similar to upstream. The area is not considered to offer nursery habitat but provides migratory habitat. Species captured by seine included spottail shiner (4) and emerald shiner (1). Outer Harbour: This area is deeper than the upstream areas, about 3 - 4 m deep and the substrate consists of a small layer of soft clayey silt overlying fine to medium sand. This fine material may represent sediments of river origin which are settling at the river/lake interface. The area is exposed to lake wave action and represents much more exposed habitat than the harbour areas. This area represents perhaps the poorest habitat in the study area because of the high exposure and soft substrates. Seining (2 hauls) in a shallow area along the west jetty yielded the following species: carp (8), freshwater drum (1), emerald shiner (12) and spottail shiner(8). East Beach: The shoreline and nearshore for about 2 km east of the harbour is a wide beach and low backshore changing to a narrow beach with moderate to high bluff(15 -20 m)backshore. The bluffs consist of sands with some clay and evidence of seepage and active erosion is present, although some armouring has been done to provide protection near the harbour. The substrate on the beach is very similar to the material to be dredged,i.e. medium to coarse sand with a trace of silt. This is a very uniform habitat type in a moderately high energy environment with extensive erosion and sediment transport occurring. Habitats are suitable for spawning and nursery by some minnow species, smelt and other species, but is not suitable for species such as bass, walleye or trout and salmon. This area is also highly turbid as a result of wave action and active erosion and sediment transport. Seining (2 hauls) yielded the following species: freshwater drum (2), rainbow smelt (1), emerald Port Burwell Dredge Monitoring Study 8 shiner (6) and spottail shiner(21). West Beach: This area is similar to the east beach, but somewhat more sheltered because of the harbour jetty. Substrates are medium sands with a trace of silt similar to the area to be dredged. The habitat is very uniform and somewhat more suitable as fish habitat because of the better wave protection. This area may also support some macrophyte growth which would offer better nursery habitat.No seining was completed in this area,however a similar community to the east beach likely exists. Summary: Aquatic habitats at the site of the dredging and disposal areas,upstream in the river and on the beaches east and west of the harbour are considered marginal offering limited nursery habitat for some warmwater species or migration habitat. The combination of high turbidities and soft, unstable substrates create these marginal conditions. The proposed dredging and disposal activities represent a short term disruption of natural processes and represent only a minor disruption in habitat use by fish. The timing of the work should also minimize any impacts. Port Burwell Dredge Monitoring Study 9 4.0 CHRONOLOGICAL HISTORY OF DREDGING PERFORMED The dredging activities completed on the Port Burwell Inner and Outer Harbours were completed over the period spanning June 4 - 6, 1996. In brief,the majority of the effort expended during the three days was on moving sediment in the Outer Harbour. Only 4 hours on June 5, 1996 were spent working on dredging the Inner Harbour. A summary of the dredging activities performed during the three days is provided below. June 4. 1996 • The dredging contractor (Dan Minor) spent approximately 7.5 hours prop- washing sediment in the outer harbour towards the south east. His intent was to clear an approach path to the inner harbour and provide a hole to accept sediment from dredging activities in the Inner Harbour. June 5. 1996 Mr.Minor spent approximately 4 hours dredging sediment in the Inner Harbour. A single channel was dredged from the mouth of the Inner Harbour along the edge of the pier and then across to the Pembina Dock. • When attempting to plow the material adjacent to the pier,Mr. Minor found the material was too hard to pull. To loosen up the bottom material he chose to perform limited prop-washing. Subsequent to this he was able to plough the sediment out past the end of the pier. Mr. Minor commented that he observed a considerable amount of debris (ie., logs, branches, cans, bottles, etc) in the sediment. This material would make it more difficult to pull the sediment as it would stabilize it similar to how riparian vegetation helps to stabilize stream banks. • The sediment dredged from the area alongside the Pembina Dock was pushed upstream into the eddy area located just north of the dock. Mr. Minor decided on his own initiative,that this would be an appropriate destination for the small amount of sediment to be removed. Subsequent discussion with Mr. Minor indicated that he felt it would not be efficient or economical to drag the small amount of sediment over the longer distance needed to permit disposal in the Port Burwell Dredge Monitoring Study 10 deeper waters of the Outer Harbour. June 6, 1996 • Mr. Minor spent approximately 4 hours prop-washing sediment in the approach channel within the Outer Harbour. He directed the sediment southeast towards the deeper waters of the Outer Harbour,north along the pier towards the beach, and west towards the shallow area directly south of Big Otter Creek. His intent was to clear the approach path to the Inner Harbour after the deposition of the sediment from the prior days activities. Port Burwell Dredge Monitoring Study 11 5.0 MONITORING PROGRAM RESULTS Monitoring of conditions within the Port Burwell Inner and Outer Harbour were carried out on Friday May 31, 1996 (prior to start of dredging activities), June 4-6, 1996 (during-dredging activities), and June 7, 1996 (after completion of dredging activities). The monitoring program as described in Section 2.0 consisted of on-site monitoring, laboratory analysis of collected samples, and bathymetric surveying. Provided below are the results of the monitoring program, and observations recorded during the monitoring period. Climatic Conditions and Observations A brief review of the weather conditions prevalent before, during, and after the dredging activities has been summarized. An onshore wind(wind corning from the west)was present for all five days of monitoring. The wind and wave intensity varied both on a daily basis and over the course of the day. The wind was considerably stronger on June 5th, 6t , and 7 th with wave heights also considerably higher. A typical pattern of increasing wind/wave height intensity and magnitude during the course of the day typically occurred for all five days. Visible inspection of the sediment plumes in the vicinity of the harbour indicated the following. Days when the wind intensity was less than that observed on June 5th , 6th, and 7th, a double plume would form in the morning. A plume from the flow in Big Otter Creek forms parallel to the shore line and is eventually blown into the east beach area by wind and wave action from Lake Erie. A second plume forms near the south tip of the breakwall and also travels parallel to the beach. Eventually the two plumes merge further east along the shoreline. As the wind and wave action intensifies throughout the day or on windy/stormy days, the two plumes merge at the outlet of Big Otter Creek. When this happens, it is not feasible to apportion the sediment load between the two sources. Bottom topography in the outer harbour combined with the wind and wave action of Lake Erie will result in varying degrees of sediment resuspension to the overlying waters. Port Burwell Dredge Monitoring Study 12 Analytical Monitoring As described in Section 2.0 turbidity, dissolved oxygen, and temperature were measured on-site, while total suspended solids, bacteria, and particle size analyses were completed offsite in a laboratory. Summarized below are general statements based on the information collected, with the raw data provided in Appendix A-Monitoring Results. Turbidity and TSS The range of concentrations observed due to natural processes varied over at least one order of magnitude for turbidity and TSS. Background TSS concentrations and turbidity measurements discharging from Big Otter Creek ranged between 18-42 mg/L,and 16-54 NTU during the five days monitored respectively. Turbidity measurements taken for the LBORP sampling program upstream of Port Burwell and within the mouth of the harbour ranged between 28-75 NTU. Background levels from Lake Erie ranged between 8-88 mg/L, and 16-145 NTU respectively. TSS and turbidity levels at the two east beach stations varied even more dramatically. The TSS concentration measured at Sites 3 and 4 during the period when dredging was ongoing ranged between 57-128 and 54-86 mg/L respectively. TSS concentrations measured on days when no dredging occurred ranged between 10-98 and 9-116 mg/L for Sites 3 and 4 respectively. Notice the sample with the highest TSS concentration for Site 4 was collected on a day when no dredging occurred. Similarly, the highest and lowest turbidity values measured at Site 3 (22-183 NTU) and Site 4 (21-231 NTU)were on the days when no dredging occurred. Typical turbidity values from the beach sites on days when dredging did occur ranged between 70-148 NTU for Site 3 and 59-135 NTU for Site 4. Comparison of historical turbidity measurements for the East Beach from the LBORP sampling program indicated a very wide range of measured values (130-820 NTU). Samples could not be collected at the west beach station for the majority of the monitoring program due to unsafe travel conditions on Lake Erie. Measurements collected on May 31, 96 and June 4, Port Burwell Dredge Monitoring Study 13 96 indicated turbidity can reduce to 10-50 NTU on calmer days. Historical turbidity measurements from the LBORP monitoring program indicated that under high wind and wave conditions the values can range between 110 to greater than 1000 NTU. Review of the measured values at the mouth of Big Otter Creek near the south end of the pier suggests a similar pattern to that observed at the two beach sites. The highest and lowest TSS concentrations (15-98 mg/L)were collected on the days when dredging did not occur. The range of concentrations during the dredging period was typically between 56-73 mg/L. Samples collected close to the boat while prop-washing in the outer harbour was underway were analyzed as worst case values. The TSS concentrations measured for the five sites range between 56 - 202 mg/L. The corresponding turbidity measurements ranged between 66-206 NTU. The intensity of the effect of this disturbance is relatively short lived and dissipates over a relatively short distance, as shown by the lower concentrations at surrounding sites. The rapid dissipation of the sediment resuspension was also visually observed by study team members. The above results indicate that natural processes even within a short time span, will vary considerably and far exceed the effect of the dredging activities completed. It should also be noted that the natural resuspension observed was only due to wind and wave action during dry weather periods. Typically, wet weather conditions would cause even more resuspension as the natural sediment load from Big Otter Creek would be added to the impact of stronger winds and higher waves from Lake Erie. Bacteria To assess the impact of bacteria resuspended due to the dredging activities, samples were collected on June 5 and June 6, 1996. Comparison of the measured results with LBORP and CURB data(see Appendix for raw values)indicate the samples collected on June 5, 1996 were lower than the mean concentration reported by the Curb data and comparable to the limited LBORP database. The measured values reported for June 6, 1996 indicated elevated concentrations both upstream and at Port Burwell Dredge Monitoring Study 14 the mouth of Big Otter Creek. Recall that no dredging of the inner harbour was performed on this day An additional point to note is the inherent variability of bacteria sampling data. An example of this point is shown by the two samples collected from the East Beach on June 6, 1996 which are approximately one order of magnitude different (50 vs 730 Cnt/100mL). When the bacteria data collected during the dredging is compared to background levels from naturally occurring phenomena, it is apparent the dredging activity completed did not produce an increase in bacteria above normally occurring levels. Dissolved Oxygen Dissolved oxygen(DO) measurements were taken during the course of the monitoring program to investigate the possibility of a DO deficit due to the sediment oxygen demand(SOD)released to the water column during dredging. Comparison of DO measurements at the surface and on the bottom at each station indicated that no differences exist between the shallow and deep water. Furthermore, all measured concentrations were greater than 6.5 mg/L with the majority of values greater than 8.0 mg/L. The water temperature was typically 15°C to 17°C during the course of the monitoring period. The Provincial Water Quality Objective (PWQO) for a cold water fishery at 15°C is 6.0 mg/L,while the PWQO for a warm water fishery at 15°C is 5.0 mg/L. Therefore,resuspension of the SOD during the dredging activities did not produce a significant impact on the dissolved oxygen concentration in the water column. Note the flow of oxygenated water from Big Otter Creek and the reaeration due to wind and waves from Lake Erie will eliminate any potential impact of resuspended SOD. Sediment Size Distribution One composite sediment sample was collected from each of the Inner and Outer Harbours to evaluate the distribution of materials characteristic to each site (see Figure 2). The results of the Port Burwell Dredge Monitoring Study 15 analyses(see Appendix)indicate that the Inner Harbour sediments are comprised of approximately 60% silts and clays, and 40% fine to medium sands. The Outer Harbour sediments are comprised of approximately 7% silts and clays, and 93%fine to coarse sands. Typically, coarse material (sands)will settle out faster than fine materials (silt/clay), and hence it would be expected that the Inner Harbour sediments would be primarily comprised of coarse materials. However,the slow rate of flow in Big Otter Creek combined with the calming effect of the breakwall extending out into Lake Erie, provides a relatively placid environment in the Inner Harbour. This results in a higher proportion of fine material in the Inner Harbour than would otherwise be expected at the mouth of a creek. Historical particle distribution analyses of material flowing in Big Otter Creek indicates approximately 74% of the sediment load is comprised of silts and clays while the remaining 26% is sand sized material. Comparison of the percentage of sandy material in the river flow versus the level measured in the surficial sediments in the Inner Harbour(26%vs 40%),indicates,as expected, that a larger proportion of the heavier sediments are settling out in the Inner Harbour than is characteristic of the background flow in Big Otter Creek. Therefore, resuspension of the Inner Harbour sediments should not result in a higher proportional loading of silty clay material to Lake Erie than the normal background levels. Review of the particle size distribution analysis indicates that the sediments present in the Outer Harbour are primarily composed of sandy material. The wind and wave action from Lake Erie will either keep fine sediments suspended, or resuspend sediments that have settled out during calmer periods. The fine material (silt/clay)present in the water is then transported along the shoreline due to the longshore current. Therefore,this results in a high proportion of coarse material in the Outer Harbour sediments which provides little risk of increased levels of silty clay material in the water column due to dredging activities in the approach path to the Port Burwell Inner Harbour. Port Burwell Dredge Monitoring Study 16 6.0 RESULTS OF BATHYMETRIC SURVEY Historical data indicates that Big Otter Creek experiences a large annual sediment load. To maintain a navigable path into the harbour for commercial and private watercraft it is anticipated that periodic dredging of the harbour will be required. A total station survey was completed June 21, 1996 to provide baseline information to evaluate the rate of sediment deposition within the Inner Harbour and the approach path from Lake Erie. Surveys will be completed during the course of 1996 to estimate the rate of sediment deposition over time. Figure 3 presents a bathymetric representation of the Port Burwell Inner Harbour and the approach path from Lake Erie. Current cross-sections based on the total station survey have been combined with historical information and are presented in Figure 4 (see Appendix). The historical cross- sections presented in Figure 4 consist of two from the Lower Big Otter Remedial Plan(LBORP)and one from a MacLaren. The LBORP cross-sections were collected in the fall of 1994 (LBORP 1) and the spring of 1995 (LBORP2), while the MacLaren section was obtained between the fall of 1986 and the spring of 1987. Care should be exercised when comparing historical cross-sections with current cross-sections as additional dredging completed in 1995 can not be accounted for,by the available information. For example, review of cross-section 2.2 indicates that a considerable amount of material has been removed from along the west side of the channel near the Pembina docks. However, large boats were observed at this location prior to the dredging completed on June 5, 1996. Therefore, the available historical cross-sections are not indicative of the conditions which existed prior to completion of the dredging on June 4-6, 1996. Review of the two LBORP sections indicate that significant changes in the channel cross-section can occur over the course of even a four month period. The true rate of bed movement and deposition will be shown through the surveys to be completed over the coming year. Port Burwell Dredge Monitoring Study 17 , i \ .....,. .6 \‘‘ ,J , , , O ` 7 1,11111r...---- , , , 1 I 1 1 I 1 APPROXEMATE DIMENSIONS OF LAND FILLED AREA ; BIG `, OTTER EAST BEACH + CREEK 4_ 'c' \i LAKE ERIE '� �r '+ 2.8 V.,‘,..1t 1' 1 4 PEMBINA 0,, \....,‘:, DOCKS 1� 1 2.2 \\y-P-, 1} LEGEND II kc' �,, 0.O HISTORICAL -,l` CROSS-- SECTIONS +'S 1 :� 5`\+ 0.0, 0.5 1, 1 0.8 CONTOUR INTERVAL 1 n 0.25, 0.75 1 14 CONTOUR INTERVAL 0.0 IIS + +', ' Aquafor 5 tti. 0\ , . Beech ;\\\ c" , �- Limited COMMA, ,l3 II `� VILLAGE OF PORT BURWELL 1 1ff BATHYMETRIC SURVEY J FIGURE 3 BREAKWALL 0 25 50 75 100 1------1 I- R 1 SCALE 1:2000 7.0 CONCLUSIONS AND RECOMMENDATIONS The primary objective of this study was to evaluate the effect of dredging activities within the Port Burwell Inner Harbour on the surrounding area. A brief summary of the key conclusions is presented below: • Big Otter Creek transports approximately 140,000 tonnes of material annually to Port Burwell and hence Lake Erie. The mass of material to be dredged within the Inner Harbour has been estimated to be approximately 1500 - 3500 tonnes, or 1.0 - 2.5% of the annual load. As the majority of the material will be pushed/pulled along the bottom, only a fraction of the total volume will be resuspended into the water column. • Aquatic habitats are considered marginal throughout the local area, offering limited nursery habitat for some warmwater species or migration habitat. The proposed dredging and disposal activities represent a short term disruption of natural processes and represent only a minor disruption in habitat use by fish. • The majority of the time expended by the dredging contractor was spent prop-washing an approach path to the Inner Harbour through the Outer Harbour. Only four hours was spent dredging a path through the Inner Harbour; ▪ Visual observations, sample data collected during the study,-and historical data indicate that natural resuspension due to wind and wave action from Lake Erie has a more significant effect on the suspended sediment concentration in the water column than the dredging activities completed. Provided below are key points which support the aforementioned statement: ► the highest turbidity measurements at the control monitoring sites (site 3 - 183 NTU, site 4 -231 NTU, site 5 - 145 NTU)were collected on days when no dredging occurred; • historical turbidity measurements at the east and west beaches are significantly higher than any values measured during this study(east beach- 820 NTU, west beach->1000 NTU); Port Burwell Dredge Monitoring Study 18 ► TSS concentrations on days when no dredging occurred were either greater or approximately equal to the values measured on days when dredging did occur; ► It should be noted that the natural resuspension observed was only due to wind and wave action during dry weather periods. Typically, wet weather conditions would cause even more resuspension as the increased natural sediment load from Big Otter Creek would be added to the impact of stronger winds and higher waves from Lake Erie. • Collection of bacteria samples and dissolved oxygen measurements indicated the dredging activities had no effect on the background concentration of either parameter. - Comparison of the particle size distribution in the Inner Harbour with the natural background distribution flowing down Big Otter Creek indicates resuspension of the Inner Harbour sediments will not result in a higher proportional loading of silty clay material than the background levels. Multiple total station surveys will be completed throughout 1996 to estimate the rate of sediment deposition within Port Burwell Harbour. This will provide the ability to predict approximately when the harbour will need to be dredged again for navigation purposes. Periodic sampling of TSS and turbidity both during and shortly after storm or high wind events, would help to illustrate the fluctuation of naturally occurring suspended sediment levels. This would provide a better understanding of the tolerance of the local environment to varying suspended sediment levels. - Review of the results from the current study and historical data indicate the combined prop- washing and plough dredging completed during the course of the three day period had no additional impact on the surrounding area. The effects of frequently occurring natural processes far exceed the worst case conditions that can be generated by dredging activities. Due to the overriding effects of natural processes,dredging activities will not expose the local Port Burwell Dredge Monitoring Study 19 environment to an unusual amount of stress at any time throughout the year. However, if it is known early in the year that the harbour will require dredging for navigation during the course of the year, it is recommended that future dredging be carried out during the spring months. This is the time of year when the natural sediment loading is highest,'and the likelihood of elevated concentrations will allow even the limited effects of the dredging activities to be assimilated. The prop-washing and plough technique is both applicable and acceptable for the dredging of the Port Burwell Harbour due to the naturally high sediment concentrations and shallow depths which exist at this location. To determine the acceptability of this technique at other locations would require a procedure similar to that completed for this study. The prop- washing/ploughing technique may not be applicable for sites with lower naturally occurring sediment concentrations, nearby sensitive aquatic habitat, or deeper channels. Port Burwell Dredge Monitoring Study 20 APPENDIX A MONITORING RESULTS Turbidity and Total Suspended Solids -Historical and Recent Observations Current Port Burwell Dredge Monitoring Study Station May 31, 1996 June 4, 1996 June 5, 1996 June 6, 1996 June 7, 1996 ID Time NTU mg/L Time NTU mg/L Time NTU mg/L Time NTU mg/L Time NTU mg/L 1 - 13:45 23.0 18 8:45 26.7 -08:30 21.1 07:30 53.7 42 09:50 44.0 37 13:50 21.1 19 12:35 16.2 23 10:15 48.2 39 15:40 26.8 19 13:00 47.2 39 2 --- 13:30 22.7 15 13:40 104.3 66 -08:30 91.0 07:45 86.8 56 09:15 153.7 98 16:05 175.0 73 13:05 78,2 68 13:00 133.7 69 3 -- 12:15 21.8 10 12:50 73.3 32 -08:30 78.5 07:50 84.3 57 09:40 183.3 98 15:50 91.0 26 13:15 123.0 88 10:05 147.7 128 12:45 70.4 101 4 -- 12:30 20.6 9 9:30 62.4 31 -08:30 81.5 07:35 92.6 54 09:45 230.7 116 13:15 20.6 12:40 58.5 30 13:25 112.3 86 10:00 80 12:40 1353 86 5 12:45 15.9 8 13:15 41.0 16 -08:30 94.1 08:05 76.6 38 09:20 144.7 67 15:55 40.7 16 13:40 128.3 88 12:50 106.0 70 6 - 12:30 8.1 4 13:25 53.2 20 09:30 43.9 24 T1 --08:30 96.1 T2 -08:30 42.8 T3 -08:30 28.0 T4 08:30 40.7 T5 --08:30 98.0 2A 09:35 206.0 170 2B 09:40 163.7 202 2C 09:50 66.3 74 2D 10:00 103.3 56 2E 10:10 124.0 162 LBORP Lakeshore Sampling Date Parameter West of Big Otter Mouth of Big Otter East of Big Otter Big Otter @ Bridge Oct 25,95 Turbidity >1,000 28.3 818 Wave Height 1-3 ft ripples 0.5 ft Nov 2,95 Turbidity 111.3 29.7 130.7 Wave Height 2-4 ft ripples 1-1.5 ft May 16,96 Turbidity 156.5 65.3 410.7 75.3 Wave Height 0.5 ft ripples 0.5 ft Bacteria Data -Historical and Recent Observations -E.Coli Current Port Burwell Dredge Monitoring Study Location June 5,96 June 6,96 Big Otter Ck upstream of Port Burwell 1,400 (Est) Mouth of Big Otter Ck - 1 110 3,000 (Est) Mouth of Big Otter Ck - 2 60 Port Burwell Inner Harbour 160 Off pier- west side 210 Off pier - south side 130 380 50 m off East Beach 120 50 150 m off East Beach-1 150 730 (Est) 150 m off East Beach-2 110 Big Otter Creek CURB Data Site Parameter 1993 1994 1995 OC 1 Geo mean 325 210 Min 50 30 Max 7,300 4,000 n 11 11 0C2 Geo mean 233 574 226 Minx 40 30 10 Max 1,600 12,600 2,600 n 9 11 11 Site OC1 - Mouth of Port Burwell Harbour .Site 0C2 - Upstream of Port Burwell (Just South of Vienna) LBORP Lakeshore Sampling Location Oct 24, 95 Oct 26, 95 Nov 3, 95 West of Big Otter Ck 40 140 <10 Mouth of Big Otter Ck 3,100(Est) 50 180 East of Big Otter Ck 420 20 150 Dissolved Oxygen -Recent Observations Current Port Burwell Dredge Monitoring Study Station May 31, 1996 June 4, 1996 June 5, 1996 June 6, 1996 June 7, 1996 Time Surface Bottom Time Surface Bottom Time Surface Bottom Time Surface Bottom Time Surface Bottom ID mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L l - 13:45 8.3 8.3 13:50 8.0 7.7 12:35 8.0 7.9 07:30 8.2 15:40 8.7 8.1 10:15 8.3 13:00 9.0 2 - 13:30 8.8 8.8 13:40 7.2 6.5 13:05 8.2 N/A 07:45 7.9 N/A 09:15 7.2 N/A 16:05 7.9 7.6 13:00 9.5 N/A 3 12:50 8.0 8.0 13:15 8.1 N/A 07:50 8.1 N/A 09:40 7.8 N/A 15:50 8.0 7.9 10:05 8.0 N/A 12:45 10.0 N/A 4 13:15 9.0 8.8 12:40 8.7 7.7 13:25 7.5 N/A 12:40 9.0 N/A 09:45 7.7 N/A 5 - 12:45 8.7 8.3 13:15 8.2 8.2 13:40 8.2 N/A 12:50 9.0 N/A 09:20 9.0 N/A 15:55 8.0 7.8 6 - 12:30 9.5 9.5 13:25 7.8 7.8 2A 09:35 8.5 N/A 2B 09:40 8.5 N/A N/A - Surface waves were to choppy to reliably assess when DO probe was near bottom so measurements not taken. Figure 4 Comparison of Historical Cross Sections with Current Survey Port Burwell inner Harbour Cross Section 0.0 176 _ I 175 17 x- _ a ^_Y4 �. o I Pi C 1►3 = I 1 72 - m air al-..-0.,,, ,N.L.; ] 270 230 290 300 310 320 Distance (m) j -- LBORP-1 -- LBORP-2 —,-- MacLaren ' - ABL-June 21,96 --- Water Level ! -- - - -- _— - I -- ._i • F Port Burwell Inner Harbour Cross Section 0.8 176 --- — --- _ i � I i 175 _ 1 I I 1 a ° 174 v.Cd P III R C 173 i I I _ 172 _ 190 200 210 220 230 240 Distance(m) i LBORP-1 v LBORP-2 IT 1 ABL-June 21,96 --- Water Level 1 Figure 4 (Cont'd) Comparison of Historical Cross Sections with Current Survey Port Burwell Inner Harbour i Cross Section 1.6 176 --- -- - — - -- - --- is I 174 o 173 , 1 1721 Iir _ : ozo - - I 171 . -, 150 160 170 180 190 200 Distance(m) LBORP-1 LBORP-2 -- MacLaren ! -x-- ABL-June 21,96 --- Water Level Port Burwell Inner Harbour Cross Section 2.2 176 -, - - -- — m 1 I I .=., 175 ' d 174 1 W 173 - , . 1 A 172 —I.---I— .---- ,--•. ---, 155 165 175 185 195 205 215 225 Distance(m) 1I -0- LBORP-1 v LBORP-2 li -- ABL-June 21,96 --- Water Level Figure 4 (Coned) Comparison of Historical Cross Sections with Current Survey Port Burwell Inner Harbour Cross Section 2.8 176 --- -- --.--.--- -..------- p 1 1 moi . - L 174 -� _ - --.' "1.-' i 112 I- -- -!- . �- , — ----- -- i 130 HO 150 160 170 180 190 200 210 220 Distance(in) _ _ 1! --0LBOR..1 —&-- MacLaren I; _______ 3 ABL-June 21,96=-- Water Level i -- 1 I 7 ORTECH 627196 2:27PM ORTECH SAMPLE ID 96-82tF1489-01 OVLV Run No. 1 Presentation:20HD Very Polydisperse model Volume Result File:1F1489 , 4 Source:Analysed Focus= 45 mm. Beam Length= 2.4 mm. Obscuration= 24.1 % SAMPLE INNER HARBOUR DISPERSED IN DI WATER SONICATED 1 MIN.(80 Watts),10000 SWEEPS(45,1000MM LENSES) OPERATOR ANNA CHOW,REPORT 96-B21 U004955-1-57 Residual= 1.157% Concentration= 0.033% Uniformity= 1.042 Span= 3.209 Specific SA= 0.8034 sq.m.1 gm MEDIAN= 48.61 urn Mode= 49.07 urn VOLUME MEAN= 70.24 um d(v,0.1)= 3.88 urn d(v,0.9)= 159.89 urn Saulter Mean= 7.47 urn. SEDIMENT SUMMARY Very Coarse Sand >1000.0 to 2000.0 microns= 0.00% Coarse Sand >500.0 to 1000.0 microns= 0.24% Medium Sand >250.0 to 500.0 microns= 3.29% Fine Sand >100.0 to 250 microns= 19.16% Very Fine Sand >63 to 100.0 microns= 17.21% Silt >2.0 to 63 microns= 54.19% CLAY <2.0 microns= 5.91% Size Result Size Result Size Result Size Result UM Below% urn Below% um Below% um Below% 0.100 0.01 1.189 3.62 14.142 22.78 168.179 90.99 0.117 0.01 1.388 4.22 16.509 24.57 196.325 93.58 0.136 0.03 1.621 4.89 19.272 26.58 229.181 95.58 0.159 0.07 1.892 5.62 22.497 28.91 267.536 97.07 0.186 0.11 2.208 6.43 26.262 31.72 312.311 98.16 0.217 0.17 2.578 7.31 30.657 35.15 364.578 98.92 0.253 0.27 3.009 8.25 35.788 39.18 425.592 99.44 0.295 0.40 3.513 9.27 41.777 44.09 496.818 99.75 0.345 0.56 4.101 10.44 48.769 - 50.13 579.964 99.88 0.403 0.76 4.787 11.86 56.931 56.25 677.025 99.96 0.470 1.01 5.588 13.65 66.459 62.11 790.330 100.00 0.549 1.32 6.524 15.63 77.581 67.95 922.596 100.00 0.640 1.68 7.616 17.30 90.564 73.79 1076.999 100.00 0.748 2.09 8.890 18.54 105.721 79.17 1257242 100.00 0.873 2.56 10.378 19.73 123.414 83.82 1467.650 100.00 1.019 3.06 12.115 21.16 144.068 87.75 1713271 100.00 1999.999 100.00 , Aver Instruments Ltd_ MasterSizer X Ver. 1.2 tivern,U.K. Serial No. 62867 Jun 96 14:27 I ,'V ORTECH#96-B21F1489-01,INNER HARBOUR 10 Volume% 100 - I - `1 _ _ - — --T _ io 0 --w r _ . . . 0.1 1.0 10.0 100.0 1000.0 10000.0 Particle Diameter(um.) alvern Instruments Ltd. MasterSizer X Ver. 1.2 alvern,U.K. Serial No. 6286 27 Jim 96 14:27 ORTECH 6/27/96 2:44PM ORTECH SAMPLE ID 96-821F1489-02 OVLV Run No. 1 Presentation:2OHD Very Polydisperse model Volume Result File:2F1489 , 3 Source:Analysed Focus= 45 mm. Beam Length= 2.4 mm. Obscuration= 22.2% SAMPLE OUTER HARBOUR DISPERSED IN DI WATER SONICATED 1 MIN.(80 Watts),10000 SWEEPS(45.1000MM LENSES) OPERATOR ANNA CHOW,REPORT 96-B21-U004955-1-57 Residual= 4.492% Concentration= 0.059% Uniformity= 0.497 Span= 1.455 Specific SA= 0.1185 sq.m.1 gm MEDIAN= 179.15 urn Mode= 185.86 urn VOLUME MEAN= 203.50 urn d(v,0.1)= 78.50 urn d(v.0.9)= 339.09 um Saulter Mean= 50.65 urn. SEDIMENT SUMMARY Very Coarse Sand >1000.0 to 2000.0 microns= 0.28% Coarse Sand >500.0 to 1000.0 microns= 2.93% Medium Sand >250.0 to 500.0 microns= 21.38% Fine Sand >100.0 to 250 mons= 59.35% Very Fine Sand >63 to 100.0 microns= 8.76% Sift >2.0 to 63 microns= 6.47% CLAY <2.0 microns= 0.83% Size Result Size Result Size Result Size Result urn Below% um Below% um Below% urn Below% 0,100 0.00 1.189 0.45 14.142 2.81 168.179 44.94 0.117 0.00 1.388 0.56 16.509 2.98 196.325 57.42 0.136 0.00 1.621 0.67 19272 3.15 229.181 69.37 0.159 0.00 1.892 0.79 22.497 3.28 267.536 79.60 0.186 0.00 2.208 0.91 26.262 3.41 312.311 87.13 0.217 0.00 2.578 1.03 30.657 3.59 364.578 91.91 0.253 0.01 3.009 1.16 35.788 3.90 425.592 94.64 0.295 0.01 3.513 1.29 41.777 4.43 496.818 96.71 0.345 0.02 4.101 1.44 48.769 - 5.24 579.964 98.07 0.403 0.03 4.787 1.60 56.931 6.38 677.025 98.82 0.470 0.05 5.588 1.78 66.459 7.85 790.330 99.27 0.549 0.08 6.524 1.98 77.581 9.79 922596 99.59 0.640 0.12 7.616 2.16 90.564 13.11 1076.999 99.81 0.748 0.17 8.890 2.34 105.721 17.99 1257242 99.92 0.873 0.24 10.378 2.50 123.414 24.61 1467.650 99.96 1.019 0.34 12.115 2.65 144.068 33.56 1713271 99.99 1999.999 100.00 ilvern Instruments Ltd. MasterSizcr X Ver. 1.2 ilvern,U.K. Serial No. 6286 27 Jun 96 14:44 i �0 ORTECH#96-821 F1489-02,OUTER HARBOUR 20 Volume% 100 90 .80 _ _70 _60 10 '• _50 X40 ...,30 _20 .10 0 0 0.1 1.0 10.0 100.0 1000.0 . . . . 10000 .0 Particle Diameter(pm.) Malvern Instruments Ltd. MasterSizer X Ver. 12 alvern,U.K. Serial No. 6286 27 Jun 96 14:39