1720 121ST ST SE 2016-01-01 MF Import

this soil would be conside�ed a wedand soii by the Corps because: 1) it is supporting a dominana of hydrophycic (wetland) plants (see "Vegetadon" section); and 2) the 6ll was placxd over a silt/organic sotl that is oonsidered a wetland soiL AIWou81� extensive exploration of the underlying soil was not possible due to the depth and denstry of the 611, the aress invesdgadon revealed soils similar to those found immedtately south of t6e fill. Immediately south of this 511ed area, wedand soils consist of about 1 foot of a dense, saturated silt loam with moderate amounts of organic matedal. Pclow the 1 foot layer, the soil consiats of at least 4 fcet of a saturated miu of silt and orgaatc material. This snbsndaa sotl mix appears to be kss d�°u chaz► the top 1 foot of silG Soila in the wetland northern portion of the site. wedand. n the southeast oorner of the site are similar to those in the The orgac�c c�ntent of the soil is less Wan chat of the northern Hydrolo� The hydrology of the sites' wetlands is dominated by high groundwater levels and the int]uencx of Silver Lake Crak. Groundwater leveis in the un5lled portion of the wetland are at or above the surface for much of the year. S6allow groundwater displaced from t6e 6lled area a000unts for a significant portion of the water storod in the un511ed portion of the wedand. It is probable that a direM ground and surface water coanection wrists between this area and Silver Lake Creek. Reference haz beea made to a culvert extending from Silver Lake Creek to the wedand under the driveway alignment paralleling the creek. Water eacchange between the creek and the wetland may not be rapid due to the relatively dense soil. T6e densiry of the fill in the northem portion of We wedand prevents significant upward groundwater movement into the fill. Evidena does eAst of surface pondinB of precipitation on top of the Cll. Water levels in the wetland in the southern portion of the site are linked directly with those of the creek and pond. Groundwater levels rise above the surface during periods of heavy precipitation and probably drop to about 1 to 2 feet below the surface during late summer and eazly fall. Vegetation Thc vegetation which grows in an area ohen reveals We long-term rnadiduns of sotls and hydrol�gy because the growch requirements of plan species can be vaY sp�cifia Wetland plantt will only grow in azeas of saturated soils, whereas upland species cannot tolerate saturated condidons. Ttie USFWS has identified wedand plant speaes and rated them as to the frequenry in which they would be found in wetland situations. My plant rated FACW (Facultative, Wetland) or OBL (Obligate) is usually found in wedands with 67% to 99% frequency.