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but non-negligible, risk of contamination during construction. Water quality monitoring may be undertaken throughout the works to ensure no negative impacts occur.


184 Environmental controls will be put in place as discussed in previous sections to construction best practises and the Environment Agency pollution control guidelines.


185 An Emergency Plan shall be put in place to ensure prompt response to any complaint of perceived impact on private water supplies, including monitoring of the water supply in question and the immediate cessation of associated water-sensitive construction activities.


186


During the construction phase, measures will be adopted by the Contractor in order to prevent silt from being washed into existing watercourses. These measures will be based on construction best practice and guidance provided by the Environment Agency and the Construction Industry Research and Information Association (CIRIA). Areas exposed due to the removal of vegetation are more susceptible to erosion during heavy rainfall or through rapid surface run-off so areas will be reinstated as soon as possible to minimise this effect.


187 Surface water flows will be captured through a series of drainage ditches to prevent water entering excavations or eroding exposed surfaces. The flows will be controlled through the use of settlement ponds, small dams, sediment traps and other hydraulic features to reduce water velocity (thereby reducing erosive power), maximise infiltration and evaporation and to remove as much sediment as possible. Surface water flows will then be discharged across open areas adjacent to the works to allow further reduction in sediment transfer and increased infiltration of flows.


188 Where areas are disturbed, the following measures may be implemented to minimise these effects:


Ditches shall be provided adjacent to tracks and other operational areas, where practicable, and will primarily be used to hold water temporarily and to encourage infiltration/discharge into the ground locally to where the rainfall hits the ground


The level of silt in run-off during construction shall be regularly monitored and if it is excessive in any area this can be managed by providing straw bales locally around the problem areas. These will filter the run-off and trap silt


Silt run-off from stockpiles and excavated spoil heaps can be contained through the placement of geotextile silt fences, mats or straw bales on the downhill side of the stockpile. Stockpiles will be covered with plastic sheeting or geotextile materials to prevent erosion through heavy rainfall


Outline Code of Construction Practice. Version 3. Page 56


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