Sustainable Building Technical Manual - Etn-presco.net

should direct water to planted areas to minimize irrigation needs. Steep sites maybenefit from terracing and retaining walls.❑ Follow all applicable erosion-control regulations.During construction, any exposed soil is susceptible to erosion and contributes to sedimentationdownstream. Most jurisdictions require erosion and sedimentation protection.❑ Stabilize soil during and after construction.Commonly used temporary controls include filtration barriers (straw-bale dams, filter-fabricfences), soil tackifiers, jute netting, hydroseeding with quick-sproutingplants like annual rye-grass, or mulch. More permanent soil stabilization may berequired: use geo-textiles (fabrics designed to filter soil from water); soil “cells” separatedwith masonry, wood, or fabric; and crib- or retaining walls.❑ Use bio-engineering.One of the most effective, and certainly the most ecological, of soil-stabilization methodsis bio-engineering, which weaves live woody cuttings into a living retaining structurethat mimics the soil-retention capabilities of matted roots. 3 The flexibility of such livestructures protects them from wash-out problems common with rigid constructions.❑ Schedule soil-maintenance tasks.A site-specific schedule of soil-maintenance tasks, in parallel with planting-maintenancetasks, should be developed.Plant Materials and Ma n a g e m e n t★ S I G N I F I CA N C E .Without plants, life on earth would cease. Plants provide oxygen; purify air; buffer climaticconditions; and modify shade, sun, wind, temperature, run off, and humidity.Landscape planting can also separate incompatible activities, allowing better use ofspace. Most cultures treat well-planned, healthy landscapes as important assets; thiscan add significant resale value to buildings. 4Site design and planting affect ecosystemdiversity. The average garden containsonly a few plant species, lessdiverse than most native plant communities.Landscapes planted with predominantlynon-native species andmaintained with pesticides tend toreduce overall diversity and increasewater use, thus damaging native ecosystems.Habitat destruction, to which nonnativeplanting can contribute, causesnearly half of all species extinctions. 5Sustainable development strives to maintainnative habitat, and avoids fragmentingit or replacing it with less diversevegetation.THE DRIPLINE: A RULE OF THUMB TO PROTECTEXISTING TREES FROM ROOT DAMAGEFigure 1