12/19/2001 Env Bd Packet - Laserfiche WebLink

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Sequencing the interval between buying the property and completing construction much of this resource is likely to be de- stroyed. The property owner is ultimately responsible for protecting as many trees as possible, with their understudy and groundcover. This responsibility is usually exercised by agents -the planners, designers and contractors. It takes 20 to 30 years for newly planted trees to provide the benefits for which we value trees so highly. Forest and native growth areas allow rainwater to naturally percolate into the soil, recharging ground water for summer stream flows and reducing surface water runoff that creates erosion and flooding. Conifers can hold up to about 50 percent of all rain that falls during a storm. Twenty to 30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Forested and native growth areas also may be effective as stormwater buffers around smaller developments. Planning Purpose of the construction sequence schedule is to address erosion prevention and sediment control in an efficient and effective manner. Appropriate sequencing of construction activities can be a cost - effective way to help accomplish this goal. The plan can be open to changes that should be discussed at the erosion control project meetings. The generalized construction activities shown in the following table do not usually occur in a specified linear sequence, and schedules will vary due to weather and other unpredictable factors. However, the proposed con- struction sequence should be indicated clearly in the erosion - and - sedimentation- control plan. • Construction access is normally the first land - disturbing activity. Exercise care not to damage valuable trees or disturb designated buffer zones as well as establish initial areas on site for preservation. • Trees should be protected around the drip line of the branches. Avoid activities that will compact the root zone. • The preserved area should be situated to minimize the clearing of existing forest cover, to maximize the preservation of wetlands, and to buffer stream corridors. • The preserved area should be placed in a separate tract or protected through recorded easements for indi- vidual lots. • If feasible, the preserved area should be located downslope from the building sites, since flow control and water quality are enhanced by flow dispersion through duff, undisturbed soils, and native vegetation. • The preserved area should be shown on all property maps and should be clearly marked during clearing and construction on the site. • Principal sediment basins and traps should be installed before any major site - grading takes place. Erect additional sediment traps and silt fences as grading takes place to keep sediment contained on site at appropri- ate locations. • Key runoff - control measures should be located in conjunction with sediment traps to divert water from planned undisturbed areas out of the traps and sediment -laden water into the traps. • Install diversions above areas to be disturbed prior to grading. Place necessary perimeter dikes with stable 3.64 Minnesota Urban Small Sites BMP Manual