1710 121ST ST SE 2016-01-01 MF Import

this soil would be considered a wedand soil by the Corps because: 1) it is supporting a dominaua of 6ydrophytic (wedand) plants (see "Vegetadon" section); and 2) the fill was plaad over a silt/organic soil that is rnnsidered a wedand soil. 1Uthoug6 exteasive e;cploration of the underlying soil was not possible due to the depth and deacity of We fill, the azeas investigadon revealed soils similar to those found immediately south of the fill. Immediately south of this 611ed area, wetland soils consist of about 1 foot of a densc, saturated silt l�am with moderate amouats of organic material. Below the 1 foot layer, the soil consists of at least 4 feet of a satnrated mix of silt and organic material. This subsudace soil mix appears to be less dense than the top t foot of silG Soils in the weAand northern portion of the site. wetland. Hydrolo� in the southeast corner of the site are similar to those in thc The organic content of the soil is less than that of the northern The hydrology of the sites' wetlands is daminated by high grouadwater levels and the influence of Silver IBke Creek. Groundwater leveis in the un6lled portion of the wetland are at or above the surface for much of the year. Shallow groundwater displaced from the �Iled area acoounts for a significant portion of the water stored in the un611ed portion of the wedand. It is probable that a direct ground and surfacx water connection exists between this area and Silver Iake Creek. Reference has been made to a culvert extending from Silver Lake Creek to the wetland under the; driveway alignment paralleling We creek. Water exchange between the creek and the wetland may not be rapid due to the relativcly dcnse soil. T6e density of the fill in the northem portion of the wedand prevents significant upward groundwater movement into the fill. Evidena does eaist of surfaa ponding of precipitation on top of the fill. 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 surfaa during periods of i,eavy precipitation and probably drop to about 1 to 2 feet below the surfaa during late summer and early fall. Vegetation The vegetation whieh grcrws in an area often reveaLc the long-term oonditioas of soils and hydrology because the growth roquiremenu of plan species can be very speci6a Wetland plants will only grow in areas of saturated soils, whereas upland species cannot tolerate saturated con�'idons. The USFWS has idend6ed wetland plant species and rated them as to the frequency in which they would be found in wetland situationc. My plant rated FA�W (Facultative, Wetland) or OBL (Obiigate) is usually found in wedands with 679'o to 99% frequenry. �