3900 BROADWAY BASE FILE 2016-01-01 MF Import

C�TY OF EVERETf STORMWATER MANAGEMENT MANUAL 1 Design and lnstallation Specl/ications Natutal vegetation can be preserved in natural clumps or as individual hees,shrubs and vines. The preservation of individual planu is more difficult because heavy equipment is generally used to remove unwanted vegetation. The points to remember when attempting to save individual plants are: • Is the plent worth saving7 Consider the location, species,size, age,vigor,and the work involved. City ordinances to save natural vegetation and trees should be reviewed. • Fence or cleazly muR areas around mes that ace to be saved. It is preferable to keep ground disturbance away from the uees at least as far out as the dripline. Plants need protection from three kinds of injuries: I. Conshuction Equipment—This injury can be above or below the ground level. Damage results from scarting,cutting of roots,and compaction of the soil. Placing a fenced buffer zone arouod plants to be saved prior to constcuction can prevent consiruction equipment injuries. 2. Grade Changes—C6anging the nahual ground level will alter grades,which affccts the plant's ability ro obWin the neces�ary air,water,aud minerals. Minor 5lls usually do not cause problems although sensitivity between species does van�and should be checked. Trees can tolerate fill of 6 iaches or Ir,ss. Fot stuvbs and other plants,the fill should be less. a. When there aze major chaages in grade, it may become necessary to supply ait lo the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. A tile system protects a hce from a raised grade. The tile system should be laid out on the orig:nal grade leading from a dry well around the tree � trunk. The system should then be covered with smell stones to allow air to c'vculate ,� . over the root area. b. Lowering tbe natural ground level can seriousty damage hees and sh�ubs. The highest percentage of the plant roats are in the upper 12 inches of the soil and cuts of only 2 to 3 inches can cause serious injury. To protect the roots it may bc necossary to tertace thc immediate azea azound the plants to be saved. If roots aze exposed,conshuction of reteining walls may bc needed to keep the soil in place. Plants can also be proserved by leaving them on an undisturbed,gcntly sloping mound. To incrcase the chances for survival, it is best to limit grede changcs and other soil dishubances to arcas outside the driplinc of t6e plant. 3. Ezcavations—E'rotcct hecs and other plants when excevating for drainfields,power,water,and sewer lines. Whcrc possible,the trenches should be routed azound ttees and lazge sh[ubs. When this is not possiblc,it is best to tunnel under thcm. This can be done with hand tools or with powcr augers. If it is not possible to routc the vcnch around plants to he saved,then the followin�should be observed: a. Cut as fcw roots as possible. w'�en you have to cut,cut clean. Backfill the trench as soon as possible. b. Tunncl bcneath root systems as close to the center of tlie main uunh to preserve most of the imporlant feedcr roots. Some problems that can be encountered with a feu.�specific vees are: • Maple,Dogwood,Red alder, Westem hemtock, Westcm ttd cedar,and Douglas fir do not readily adjust to changes in environment and special care should b�taken to protect these trces. Volume fl—Construction Stortnwater Pollution Preventron 3-2