 The sides of Carnsew Pool are built of rubble and slag, and New Pier was also built, to direct water through sluices, into the estuary; thus flushing silt out of the river channel adjacent to Harvey's foundry.The complex system maintained the port facilies which allowed the two competing foundries to increase their national and international roles.As well as building steam engines, Harvey's developed their business with overseas exports, shipbuilding and ship-breaking.