Manly Lagoon Dredging Project - Manly Council - NSW Government

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Manly Lagoon Dredging Project – Review of Environmental FactorsPrepared for Manly and Warringah Councilsincorporated to test the treated dredge spoil prior to its potential reuse or disposal to landfill.Neutralisation will be achieved by dosing the dredged material with agricultural lime.Contaminated Lands ManagementPrecautions must be taken when dredging near the EPA Contaminated Site (Former Landfill)at the end of Addiscombe Road. When dredging adjacent to this known contaminated site nodisturbance of the bank will be permitted. Visual gross contamination testing, forcontamination identifiable by sight or smell will be undertaken during dredging, however noadditional sediment analysis for contaminants identified in Table 5.3 is proposed forsediments in the Addiscombe Road area during dredging. Treated dredge spoil from withinthe geobags will however be chemically tested in order to determine its suitability for reuse,or requirement for disposal at landfill.In order to limit any overburden pressure that may increase leaching of materials from theformer landfill site, the proposed dredging works will have no site presence at all on theformer landfill site. This will ensure no site vehicles or heavy plant or machinery utilise thissite.It should also be noted that since neither the water level in the lagoon, or surrounding waterlevels will be altered by the proposed dredging works, there will be no resultant change inthe hydraulic gradient in the Addiscombe Road area as a result of the works, andconsequently no change in the rate of leaching of contaminants from the former landfill isexpected.If contaminated materials are encountered during the proposed works the material will needto undergo chemical assessment in order to classify the type of waste, in accordance withDECC’s Waste Classification Guidelines (2009d). Once the waste is properly classified,appropriate management options for the material can then be considered, as required underthe PoEO Act and the associated regulations. DECCW (EPA) should be consulted regardingfurther guidance on managing specific waste types.2 July 2010 Cardno (NSW/ACT) Pty Ltd 50H:\Doc\2010\Reports.2010\Rep2580v4.doc
Manly Lagoon Dredging Project – Review of Environmental FactorsPrepared for Manly and Warringah Councils5.2 Climate and Air QualityExisting EnvironmentThe closest operating Bureau of Meteorology (BoM) weather station to the proposed workssite is the Sydney (Observatory Hill) weather station (Site Number: 066062), locatedapproximately 11km distant in a south-west direction. A search of the BoM Climate Statisticsfor Australian Locations (on 10 July 2009) revealed a range of statistics for the area, detailedbelow. Due to the proximity and the relatively consistent coastal location of the proposed siteand the Sydney (Observatory Hill) weather station, the climate statistics below can beconsidered representative of conditions at the proposed works site.Mean maximum temperatures range from 16.3°C in July to 25.9°C in January, whilst meanminimum temperatures range from 8.0°C in July to 18 .8°C in February. The wettest periodfor the area is between February and June, with the highest average monthly rainfallrecorded in June (130.6mm). The driest period of the year on average is between Augustand December, with the lowest average monthly rainfall recorded in September (69.4mm)(BoM, 2009).Wind data for the Sydney (Observatory Hill) weather station shows that average monthlywind speeds in the afternoon (3pm) are substantially higher than in the morning (9am).Average monthly afternoon wind speeds are particularly high (>17km/h) from August toJanuary. The highest average monthly wind speed in the morning is recorded in August(13.3km/h), and in the afternoon is recorded in December (19.5km/h) (BoM, 2009). Due tothe coastal location of Manly Lagoon, as opposed to the harbour location of the Sydney(Observatory Hill) weather station, wind speeds at the proposed works site may be slightlyhigher.Figures 5.3 and 5.4 give a guide to the varying degrees in wind direction and velocity in themorning and afternoon for each of the months of the year using data from the Sydney(Observatory Hill) weather station (Site Number: 066062), respectively. Winter winds aregenerally westerlies in the morning, remaining as westerlies or occasionally shifting tosoutherlies later in the day. In spring the prevailing morning winds are generally westerlies,changing to easterlies in the afternoon. In summer the prevailing morning winds aresoutherlies, changing to easterlies in the afternoon. Autumn winds are generally westerlies inthe morning, and predominantly easterlies in the afternoon (BoM, 2009). Wind direction isgenerally more variable in the summer and autumn months, and wind speeds are generallyhigher in the spring and summer, particularly in the afternoons, as discussed above.2 July 2010 Cardno (NSW/ACT) Pty Ltd 51H:\Doc\2010\Reports.2010\Rep2580v4.doc
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Manly Lagoon Dredging Project - Manly Council - NSW Government

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