Fenit Harbour
Dumping at Sea Application
Site selection report
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EPA Export 24-03-2015:23:12:12 14996 Dump Site selection report January 2015
ISSUE FORM Project number 14996 Document number Document revision Rev A Document title Dump Site selection report Document status Draft Document prepared by Ken Fitzgerald Document checked by
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Table of contents
1 INTRODUCTION ...... 1
2 CRITERIA FOR DUMP SITE SELECTION ...... 1
3 SUPPORTING DOCUMENTATION, CONSULTATION AND REPORTS...... 1
4 DUMP SITE SELECTION PROCESS ...... 2 4.1 Stage 1...... 2 4.2 Stage 2 ...... 3 4.3 Stage 3 ...... 5 Table 1 Screening for Appropriate Assessment ...... 8 Table 2 Natura Impact Statement ...... 8
5 HISTORY OF PREVIOUS DUMPSITE ...... 8
6 DISCUSSION ...... 9
7 ANALYSIS ...... 11
8 CONCLUSION ...... 12
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1 INTRODUCTION
Malachy Walsh & Partners (MWP) was commissioned to prepare a Dumping At Sea (DAS) application for ongoing maintenance dredging work in Fenit Harbour. As part of the DAS application submission a dump site selection report has to be completed.
This report sets out the criteria that were used to select the dump site and discusses the merits and reasons for the final site selection.
2 CRITERIA FOR DUMP SITE SELECTION
The following criteria were used in the dump site selection process:
. Avoidance of shipping lanes and main navigation routes
. Avoidance of known seabed archaeological features
. Avoidance of Natura 2000 sites
. Avoidance of fishing grounds and nursery areas for fish and aquaculture
. Avoid impacts on Blue Flag beaches
. Selection of area of sea bed with reasonable depths of water For inspection purposes only. Consent of copyright owner required for any other use. . Selection of an area of sea bed that has a suitable profile or depression
. Location that has favourable current regime
. Location that has suitable bed characteristics for receipt of dredged material
. Minimisation of impacts on benthic communities within and surrounding the dump site
. Examination of previously used dump site locations and experience with these locations
3 SUPPORTING DOCUMENTATION, CONSULTATION AND REPORTS. In completing this report the following information, consultation and reports were utilised to inform the selection process.
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. Review of previous dumping at sea licence applications
. Review of admiralty charts and previous bathymetry surveys
. Review of NPWS web mapping to identify European Designated sites
. Completion of initial bathymetry for two possible site locations
. Completion of initial tidal flow metering at two possible site locations
The following consultations were undertaken
. Consultations with the Fisherman from Fenit Harbour, about the suitability of a number of locations within the Bay.
. Consultations with the Harbour Master at Fenit
. Consultation with the Harbour Pilot in the port relative to navigation and shipping lanes
. Consultation with Development Applications Unit (DAU)/(NPWS)
. Consultation with the Underwater Archaeology Unit (DAU)
. Consultation with the EPA inspector to discuss the proposed project and application
Consultation with the planning authority Kerry County Council was not undertaken as they are the client for this application and they own and operate the harbour. However their representative is the Harbour Master in Fenit and he was consulted throughout the process. For inspection purposes only. Consent of copyright owner required for any other use. Following from the above a constraint map was prepared which set out two possible locations for a dump site within Tralee Bay. The constraints as set out were then used to further examine the possible sites. It should be noted that other possible locations for dumping at sea were discussed with stakeholders but were immediately discounted for fishery reasons and in order to avoid sensitive ecological and environmental effects along with potential impacts on blue flag beaches.
The dump site selection process was driven by constraints analysis and an iterative process where each location was examined and then discounted, or investigated further.
4 DUMP SITE SELECTION PROCESS
4.1 STAGE 1.
Initially a number of potential sites were discussed at a high level for the purposes of feasibility or not. Some of the sites were immediately discounted for fishery or environmental reasons or for reasons of depth etc.
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Figure 1 below shows the initial list of potential search areas.
Area outside this line excluded
Fenit
Area due east of this line excluded due to oysters
Figure 1. Potential search areas and initial exclusion zones .
In the initial phase of the process some high level constraints were set out. The area outside of Tralee Bay due west of a line from the Brandon Point to Kerry Head was automatically excluded due to depths of water, distance from the dredge location and exposure to weather.
A second exclusion zone was adopted for the area of inner Tralee Bay and estuary due east of Fenit due to the existence of the oyster fishery and the existence of the Tralee Bay Shellfish Area.
Three potential search areas were initially identified as outlined above in Figure 1. These were For inspection purposes only. initially selected due to suitability Consentof water of copyright depths, owner requiredproximity for any toother the use. dredge location and they were outside the two exclusion zones.
4.2 STAGE 2
This stage then progressed to look at the search areas and Tralee Bay outside of the exclusion zones. At this stage a constraints map was developed which showed the following constraints:
. Designated Natura sites, Special Protection Areas (SPA) and Special Area of Conservation (SAC) . Natural Heritage Areas (NHA) & Proposed Natural Heritage Areas (pNHA) . Location of recorded wrecks on the sea bed
The location of these designated sites can be seen in Figure 2 below. Once this was set out one of the search areas due west of Fenit and due east of Castlegregory Beach was excluded as it was within the SAC and pNHA. Historically (prior to 1996) there are some records of material being deposited in this general area , but the practice was not repeated as this was also a prime area for the nursery of fish and it was also close to the pristine sandy beaches along this section of Tralee
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Bay. There are also a number of known wrecks in this general area. The shallow water depths also make it unsuitable for navigation with a suction hopper dredger of a certain scale.
This then left two search areas, namely Area A (shown in Red) which is in outer Tralee Bay outside of Mucklaghmore Island and Illaunnabarnagh Island as can be seen in Figure 2 below, and the second area is Area B (shown in Purple) which is located in the vicinity of previous dump sites used for previous deposition of dredged material from the harbour dating back to 1996.
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Figure 2. Constraints map and location of search area A and B.
At this point some baseline bathymetry was undertaken by Hydrographic Surveys Ltd for both locations to establish the bed profile. In addition current metering was undertaken by Hydrographic Surveys Ltd at both sites to establish what the current regime was.
Site A is the outer site and bed level depths at this location are 27m CD and this location has good separation from the designated sites. This area of water is open to the wider Atlantic swell and weather.
Site B is located inside the islands of Mullaghmore and Illaunnabarnagh and is within a depth of water of 13 to 16m CD. This area is closer to the harbour dredge location and is in a somewhat more shaded location in terms of weather exposure. It is located closer to designated sites as can be seen from Figure 2 above.
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The data collated at both potential sites indicated that either site would be a viable option from a technical dredging point of view, but acknowledging that the outer site was more challenging in terms of weather, swell and distance from the dredge location.
Before progressing further it was decided to consult with the fisherman within Fenit Harbour and the Harbour Pilot who know the bay in terms of environment, fishing, weather, navigation etc. They were also involved in the initial dump site selection process prior to the capital dredge that was undertaken in 1996 and so are well informed on the nature of the bay and the successful nature of previous dredging and dumping campaigns over the years.
At the meeting in the Harbour Office in Fenit the constraint mapping was presented to them and we went through the obvious identified constraints that exist. From a fishing perspective Site A was not favoured as this was a very good fishing ground and the fishing community would strenuously object to this location. The harbour pilot also had concerns as this was close to the main navigational route that was used by large Liebherr shipping vessels entering the bay and approaching the port. In general both parties had concerns due the exposed nature of the location in terms of weather and swell and the distance from the dumpsite for transport of materials.
In the opinion of the fishermen and based on their previous experience since 1996 they felt that Site B was the optimum location as it was not in an area where they had concerns in terms of fisheries. In addition they stated that this location has a localised depression and is one of the deeper areas inside the islands that would be suitable. These criteria also came into play when selecting this location previously. Upon looking at the constraint mapping the area has no known wrecks and is also outside of the designated sites.
It can be seen from Figure 2 above that the location of the previous dumping at sea sites is adjacent and overlaps Area B. The Harbour Pilot had no navigational issues for this location. While the location is closer to the beaches at Barrow and Banna and the SAC and SPA in this area, there is still For inspection purposes only. an adequate separation from the shorelineConsent of copyright and featuresowner required of for importance. any other use. It is also closer to the dredge location which allows for more efficient journey and turnaround time for the suction hopper dredger to dump and return to port.
The initial bathymetry and tidal current metering showed that the site was suitable from a high level perspective, but it warranted further investigation.
At this stage based on the information gathered to date and based on the consultations it was decided to eliminate Site A in the outer bay and to concentrate on the inner Area B search area.
4.3 STAGE 3
This stage focussed on more intensive examination of Area B and it included the following studies:
. Underwater Archaeological Impact Assessment completed by Lar Dunne Archaeology in conjunction with the Side-scan Sonar and Magnetometer Survey Report completed by Hydrographic Surveys Ltd
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. Baseline Characterisation Report completed by Aquafact
. Sediment Transport Model complete by Aquafact
. Current speed and direction assessment based on the deployment of an ADCP unit deployed at site B in July 2014 for a period of 15 days. This was undertaken by Hydrographic Surveys Ltd.
. Sediment sampling from the proposed dredge material within the harbour and analysis of same by RPS Laboratories
. Natura Impact Statement (NIS) addressing both the dredge location and the proposed Area B dumpsite location.
The consultation that was undertaken with the DAU and the Underwater Archaeology Impact Assessment completed by Lar Dunne Archaeology confirmed that the area of seabed proposed for the dumpsite location has no wrecks or archaeological conditions that would mitigate the proposed site being used for disposal of dredged material.
The baseline characterisation report completed by Aquafact sets out the sampling regime and results. The sampling included a benthic faunal of the dumpsite along with grain size analysis and carbon content. A sediment characterisation survey was undertaken for both the dumpsite and dredge location. The Aquafact report outlines the results of the sampling and analysis and the report discusses the findings. In summary the dumpsite is primarily classified as consisting of fine/medium sand, coarse/medium sand and coarse/very coarse sand, but has areas of hard ground on the western half. From a faunal perspective the area is classified under Fossitt (2000) as SS1 Infralittorral gravel and sands. All species observed are typically of the gravelly/sandy habitat in the area and the species present represent a balanced mix of longer lived deeper burrowing equilibrium species and For inspection purposes only. smaller short lived opportunistic species.Consent of copyright owner required for any other use.
The sediments from within the harbour area were classified as muddy sand throughout by Folk (1954), being dominated by silt clay and very fine sand for the most part. The Aquafact Baseline Characterisation Report is included as Attachment B2 to the application form.
The Sediment Transport Model report is included as Attachment J to the application form. The report sets out the basis for the model, the model calibration with the results of ADCP survey and the hydrodynamics of the bay.
The model simulation covered a 50 day period from the 18th July to the 6th of September 2014 and the results of the simulations for different points in the tidal cycle are included in the report. The following is an extract from the report’s conclusion;
The general tendency over the 50-day simulation period is for the silt deposition to migrate southwards, then westward and eventually northwards out of Tralee Bay and westward to open sea. Temporary deposition in the reef areas to the south, southwest, northwest and the reefs further to the west of the disposal site is predicted. Deposition rates over the 50-day simulation period are
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EPA Export 24-03-2015:23:12:12 14996 Dump Site selection report January 2015 generally in the wider areas of the reefs to be less than 0.2 to 0.5kg/m2 but local highs of up to 3kg/m2 are predicted.
Due to the higher settling velocities the sand fraction is less mobile than the silt with the heavier fractions(representing coarse and very coarse sands) shown to remain deposited within the disposal site. The lighter sand fractions of medium to very fine sands are transported to the south of the site where they remain. Only the very fine Sand migrates towards the reef area to the south and southwest similar to the silt fraction but of a considerably lower rate.
In conclusion the silt and very fine sand fractions of the sediment will be transported from the disposal site under ambient tidal currents and will temporarily deposit in the surrounding reefs to the northwest, south, southwest and west. Deposition rates are shown to be generally less than 0.2 to 0.5kg/m2 but local highs of up to 3kg/m2 are predicted. In terms of sediment depth 1kg/m2 represents a sediment depth of 0.55mm per m2 at density of 1800kg/m3.The heavier sand is shown to remain at or near the disposal site. This amount of additional sediment depositing on any substrate does not have the capacity to cause smothering or blocking of light. No impact is therefore considered likely on any habitat or species.
The ADCP results were utilised by Aquafact in the completion of the Sediment Transport Model and are available upon request if required.
The results of the sediment sampling and analysis are included in the Baseline Characterisation report completed by Aquafact and this report is attached as Attachment B2 to the application form.
The results for the analysis of sediments undertaken and completed by RPS are included in Attachment B.1 (II) to the application form. The results conclude that sediments have characteristics that fall within Class 1 or Class 2 of the guidance levels for contamination in sediment to be dredged. Accordingly the sediment is regarded as being marginally contaminated, but importantly is not likely For inspection purposes only. to cause biological effects/toxicityConsent to marine of copyright organisms. owner required This for any means other use. that the material being dredged from within the harbour does not have a negative or damaging profile and would not have a negative effect on the faunal communities of the proposed dumpsite.
The Natura Impact Statement (NIS) was completed to address both the dredge location at Fenit Harbour and the proposed dumping at Sea location in outer bay. This report is an extensive document and looks in detail at the potential impacts on Natura 2000 sites. It includes a detailed analysis of the potential risks associated with the dredging operations and the deposition of material on the sea bed at the proposed dumpsite. The NIS is included in Attachment A.2 to the application form.
The findings of the Screening for Appropriate Assessment and Natura Impact Statement are outlined in Table 1 and 2 on the following page:
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TABLE 1 SCREENING FOR APPROPRIATE ASSESSMENT The project entails maintenance dredging at Fenit Harbour and disposal of the Project dredge material to a dumpsite in Tralee Bay in County Kerry Project Proponent Kerry County Council Project Location Fenit Harbour and Tralee Bay It has been concluded that the proposal to dredge Fenit harbour and dispose of the dredge materials at a dumpsite in Tralee Bay is likely to have a significant effect, or significant effects cannot be ruled out at this stage, on the following Natura 2000 sites:
Conclusion Tralee Bay and Magharees Peninsula, West to Cloghane SAC (002070) Akeragh, Banna and Barrow Harbour SAC (000332) Tralee Bay Complex SPA (004188) Magharee Islands SAC (002261) Magharee Islands SPA (004125)
TABLE 2 NATURA IMPACT STATEMENT The project entails maintenance dredging at Fenit Harbour and disposal of the Project dredge material to a dumpsite in Tralee Bay in County Kerry Mitigation measures include: Restrictions on the timing of dredging Mitigation Water quality management Control of overflow from suction hopper dredger
In conclusion, provided the recommended mitigation measures are implemented in full, it is not expected that the proposal to carry out maintenance dredging at Fenit Harbour and disposal of the dredge material to a dumpsite in Tralee Bay will result in an adverse residual impact on the Natura 2000 sites considered in this NIS, namely: For inspection purposes only. Conclusion Consent of copyright owner required for any other use. Tralee Bay and Magharees Peninsula, West to Cloghane SAC (002070) Akeragh, Banna and Barrow Harbour SAC (000332) Tralee Bay Complex SPA (004188) Magharee Islands SAC (002261) Magharee Islands SPA (004125)
5 HISTORY OF PREVIOUS DUMPSITE In 1996 a large capital dredge of the order of 240,000m3 was undertaken to facilitate the development of the marina, eastern breakwater and the new spring pier. At the time the dumpsite was elected by the design team in conjunction with the Harbour Master, Fishermen and local stakeholders. That site is overlaps the current proposed area of Site B outlined above.
Over the years a series of maintenance dredging campaigns have been undertaken in Fenit and the material has been deposited in the vicinity of the currently proposed dumpsite. This location has proven successful previously and there have been no adverse effects locally or indirectly.
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The material deposited previously was placed using bottom opening dredge barges or suction/trailer/hopper vessels that have a similar mechanism to discharge the loads to the sea bed. On each of the occasions the dredge captain and a dedicated crew member monitor the visual scale of the plume as it is discharging and dispersing in the water column at the dumpsite. Typically and depending on the capacity of the dredge vessel hopper there can be multiple trips over a period of weeks and varying times of the tide. On previous dumping campaigns there has been no documented negative effect.
The previous dumpsite location has proven to be a suitable one and has been used many times without issue. The choice of this location originally back in 1996 was informed by local knowledge, the fishermen’s views, the harbour pilot and a review of the admiralty charts.
The proposed dump site area B as discussed above and as examined in the various studies shows the suitability of the site for dumping at sea of dredged material.
6 DISCUSSION The process of selecting a suitable dump site in Tralee Bay for the disposal of dredged material from Fenit Harbour was undertaken in stages between 2013, 2014 and concluding in January of this year.
The process was an iterative process which involved a series of consultations and studies being completed as each potential site was examined, eliminated or investigated further.
Dredging has been undertaken in Fenit over the last 20 years on a regular basis and the material from each dredge campaign has been disposed of at sea within Tralee Bay. Over the years a number of dumping at sea permits were secured from the Department of Marine and Natural Resources or Department of Agriculture Fisheries and Food.
For inspection purposes only. Consent of copyright owner required for any other use. Given the physical shape of the harbour and its piers and structures within the bayy there will be an ongoing requirement for maintenance dredging as the harbour footprint is an obstacle within the footprint of the bay, and interrupts the natural hydrodynamics of the area. This in effect means that the harbour footprint acts as a barrier or semi enclosed structure that catches sediment by means of reduced and impeded flows. The harbour area has an ongoing accumulation of material within the commercial berth and the inner harbour area and this will continually need to be dredged going forward.
Importantly all the material accumulating within the harbour is coming from the wider bay system which is dynamic. This coastal system has constant movement and deposition of sediments and material within the bay due to currents, coastal processes and due to the impacts of storms and extreme tides.
The maintenance dredging campaigns effectively are moving material from one part of the system to another part of the system within Tralee Bay. Once dredged, the natural cycle will continue with material accumulating once more.
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Importantly there is no industrial activity or discharges within the harbour area, nor is there any heavy industry of boat building or repairs. There are no sources of industrial wastes or emissions within the harbour. The main activity of the harbour is the shipping of Liebherr cranes, the activities of the marina and a small inshore fishing fleet. There is no slipway within the harbour to facilitate the cleaning or anti fouling of boats, or to facilitate any large scale repair or painting works. Any maintenance or repair work is facilitated by the removal of boats from the water and they are then repaired off site or within the nearby former railway yard, in the boat club yard, or at private residences, or dedicated boat repair premises in Tralee or elsewhere.
The evidence from the sampling and historic knowledge of the harbour and the coastal processes shows that the material that is accumulating within the harbour and surrounds is not contaminated and is typical of what exists within the bay.
In recent dredging campaigns the dredging has been undertaken by both suction hopper type dredgers, but also with a back hoe excavator mounted on a boat or barge, in conjunction with transport barges. Various methods have been used over the years and without any negative effects on the adjacent oyster fishery, blue flag beaches or the wider bay area.
Both the dredging and dumping at sea activities have been managed by the Harbour Authority in conjunction with the dredge captain and local stakeholders and no issues have been identified throughout previous campaigns.
The assessment undertaken as part of the dump site selection process have shown that the material being dredged is not contaminated and that it is suitable for deposition at the proposed dumpsite location.
The assessment of the dumpsite location has shown that it is suitable to receive the material from the dredge footprint within the harbour. For inspection purposes only. Consent of copyright owner required for any other use. The hydrodynamic model has shown that less than 20% of the material will deposit and stay within the dumpsite location and the remainder will re-disperse within the wider and outer bay area. Any accumulation of material on reefs will be minimal and this deposition will be temporary as the natural currents will eventually re disperse the material within the wider area. Any temporary deposition of material will not have a detrimental effect on faunal communities within the habitat.
Given that material is not contaminated and occurs within the bay, then the fact that the majority re-disperses within the dumpsite area and the wider bay should have no negative effects, as in effect the dredging and deposition process is mimicking what occurs naturally in the system.
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7 ANALYSIS
The following table sets out the criteria for site selection and shows how the potential sites comply with the various criteria:
Selection Criteria Site A Site B Notes Avoidance of shipping lanes and √ √ Both sides avoid, however Area A main navigation routes is in closer proximity to shipping lanes Avoidance of known seabed √ √ Both sites avoid archaeological features Avoidance of Natura 2000 sites √ √ Both sites avoid Avoidance of fishing grounds and √ Area A was not preferred by the nursery areas for fish and no fishermen as they regard this as aquaculture prime fishing grounds Avoid impacts on Blue Flag √ √ Area B is closer to Blue Flag beaches beaches but there is still adequate separation Selection of area of sea bed with √ Area A has 27m CD bed level reasonable depths of water no which is not ideal Selection of an area of sea bed √ √ that has a suitable profile or depression Location that has favourable √ √ While both have good or similar current regime characteristics, Area A is in more open water and more exposed Location that has suitable bed √ √ For inspection purposes only. characteristics for receipt of Consent of copyright owner required for any other use. dredged material Minimisation of impacts on no √ In site A there is the potential to benthic communities within and impact on the fishery surrounding the dump site Examination of previously used √ Site B overlaps with historic dump site locations and no location of successful dumpsites experience with these locations Favourable approval from all no √ Fishermen had concerns with Area stakeholders A due to good fishery grounds. Proximity to port and dredge no √ Shorter route to the dump site location and less exposure to weather
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8 CONCLUSION The process of selecting a suitable dump site is one that that involves a series of steps including baseline surveys, reports, consultation and a review of existing information and historical practices in the area.
This report sets out how this process was undertaken and the reasons why certain decisions were taken. There are multiple constraints within the Bay and there are different physical properties in the outer bay as against the inner estuary area due east of Fenit Port.
The consultation with stakeholders was an important step and informed the decision making process and also brought relevant and good experience to the process.
Based on this assessment and on the results from the various reports/consultations completed Malachy Walsh & Partners are of the opinion that Dump Site B is the optimum location for the dumping at sea site.
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Appendix
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