11000 16TH AVE SE 2016-01-01 MF Import

� � � I y I C� H HN � � � �I K � � y � � H � � OCT 24 '88 14�14 DHVID EVRNS & RSSOCIHTES GELLEVU P.ci17 !p H � L�7O � H t7 O � �� g Wed l�mction ; � � y � � Qverall wedand value is assessad by evaluating each individuai wetland funccion. Major g n H wedand functioas and factors to consider are 1) hydrolo�ic supporc, 2) storm and flood , o e �n water storage, 3) groundwater rechar�r; 4) water qualiry improvem�nt, and 5) biologcal �� support and diversiry. Iiydrolo�ic support is closely rclated w habitat productivity and z y �, groundwater recharge: Low hydrologic support is equated with isolated depressions havmg y � �' , temporary saturation\uiundadon during the growing season, w:uch affords lictle support for aquatic habitat and arher wedand functions. Storm and flood water storage raangs are higher when associated with urban lwd and wetland sizes d�at excezd 5 aares. Groundwater recharge capabiGties are direcdy related to undcrlying geology, soils, and , sur:ace topography as well as wedand si��. Small isolaced wetlands having tempo•ary inundation provide little or no groundwar.er recharge valuz. The us.� of wetlands for higher wa?ar q�iality is successful when sedimentation and ; biofiltrapon factors aze present. Oper, watzr wedands having addition�il vegetation zor.es, especialiv emergent marsh plant ce.nmuniues, offer greater potendal for assirnilation of nutriencs and adsorpuon of mineral particulate matter and pollutanu. Tl�e natural biological funcuons of wetlands provide bbsis for many food cbains and related habitau. Generally, wetlands that can provide diiferent habitat types and vegetation zones will be i�""+� ahle to support a hi�lier diversiry of.pecies. The size of the wetland 'u again an important '�� value factor; bowever, terrestrial wildlife and aquatic lifa benefit greatly from habitat diversity of�en not present in small, seasonally iiiundated wetlands. 1 1�-� The 1986 report completed by Terra Associates, Inc. (Geotechnical �'ngineering Study, , Project No, 309) states that t�e entire projec[ site is underlain by dense, camented glacial soils at a relaavely sLallow depth, T1�is cementad silc, sand, and gravel condition allows (.,.�„� ' surficial waters [o"perch" on top of it. The site has received much disturbance fram losging � ,.,�1 activities and added fill material. The fill material is very eviden[ on the Phase 1 property's - eastern hal� as it is visible in mounds and covered with young rcd alder and willow trees. 'I'he same geotechnical study reports the projCct site was graded 10 to 15 years ago with up i' 1 to 4 feet of added wood debris and silry gravels pushed out over die site. . The obsecved and reported disturbances have altered the e�ting wedand ar�as and associated lowland drainage area. Water movemenc rluough the area has been blocked and 0��'�� diverted, creating small, ponded depressions supporting non•continuous hydrophydc vegetation. Watcr ilow has Leen interrupted and altered by pas[ filling and grading. The i physical condiuons of a subsudace hardpan condiuon do not pennit a larga amouni of p�. retention and many of the ponded areas lack sdequate groundcover vegetation for � �,�! ° biofiluation funcdons. T�ue to the subsurface candi[ions, tl�ese wedands funcuan a� g:oundwater discharge areas and not recharge arcas. Dua to small sized wetlands (less than 1.5 acres), lack of plant diversity and associated habitat, limited flood/srorm water srorage capability, and no groundwater recharge or water quality benefits, the areas represent low value wedands. The extent of past lo�ing, grading, and fAlling activities further reduces the value of these wetlands.