Quaternary Research Center. Soils and Land Use in the Puget Sound Basin

Transcription

1 Quaternary Research Center Home About People Research Journal Resource Center Events Facilities Soils and Land Use in the Puget Sound Basin Ronald S. Sletten, Dept. of Civil Engineering, University of Washington, Seattle, WA Dale Snyder, Consultant, Redmond, WA (Formerly with the Soil Conservation Service) Lyndon C. Lee, L.C. Lee and Associates, Inc., Seattle, WA (Formerly with the EPA) Derek Booth, King County/University of Washington, Seattle, WA David J. Marrett, Dept. Crop and Soil Sciences, Oregon State University,

2 David J. Marrett, Dept. Crop and Soil Sciences, Oregon State University, Corvallis, OR Prepared for the: American Society of Agronomy, Crop Science Society of America, Soil Science Society of 86th America Annual Meeting, Seattle, 1994, Wednesday, November 16, Sponsored by Division S-5, Carolyn Olson, chairperson. Contents Acknowledgments Introduction Itinerary and map of travel route Satellite Image of Seattle area Seattle and its greater metropolitan area History Geological history of northwest Climate and Vegetation Summary Guide to tour stops En route from Convention Center to Queen Ann Hill Stop 1 - Kerry Park, Queen Ann Hill Slumping Earthquake hazards En route from Queen Ann Hill to Sammamish Plateau Lake Washington watershed Stop 2 - Sammamish Plateau site

3 Alderwood Soil Series Everett Soil Series Indianola Soil Series Norma Soil Series Sammamish Soil Series Seattle Soil Series Stop 3 - Lake Sammamish Park Lake Sammamish Park orientation Soils map of site Geomorphology of site Wetland function and values Stop 4 - Mercer Slough Appendix 1: SCS soil series descriptions Alderwood Series Everett Series Kitsap Series Norma Series Indianola Series Seattle Series Sammamish series References Acknowledgments Information regarding current and past landuse is contained in a diverse body of

4 Information regarding current and past landuse is contained in a diverse body of literature. We are grateful to a number of individuals who were very helpful in providing information that we requested. We acknowledge the assistance of the Soil Conservation Service for providing updated information, in particular Terry Aho and Karl Hipple, Spokane, WA, and Kirsten Stuart, Lincoln, NB. We appreciate receiving copies of "Geology of Seattle" from William T. LaPrade, Shannon and Wilson, Inc. We are grateful to David Kral and Mary Ann Nicholson of ASA, CSSA, and SSSA for providing logistical support. We appreciate the cooperation of Conner Development Co., Bellevue, WA for permission to access their site (Alderwood-Everett site) which is currently under development, and for providing the use of a backhoe and operator to prepare the soil section. Finally we wish to acknowledge the support and inspiration that Fiorenzo Ugolini has given over the years to several of the authors of this guide. Introduction We will visit sites with examples of some of the more extensive and significant soils in the vicinity of Seattle, Washington. The city is located within the Puget Sound Basin bounded on the west by the Olympic Mountains and on the east by the Cascade Mountains. The Seattle area was deglaciated ca. 13,500 years ago and many of the present landforms in the region are related to these most recent continental and alpine glaciations. Consequently, most soils have developed in glacial drift or Holocene alluvium; bedrock exposures are infrequent. Glacial topography, impermeable subsoils, and long mild wet winters contribute to the formation of hydromorphic soils and wetlands. Wetlands are prevalent in many areas and are among the principal land use issues concerning soil scientists. We will visit sites with soils formed in glacial till, outwash, alluvium, and lacustrine deposits, and discuss their relationship to the formation of wetlands. Land development on steep slopes is common in this seismically active area, therefore earthquake hazards, slope stability, and erosion are important land development considerations. In addition, groundwater contamination and habitat loss will be discussed briefly. An overview of current land use issues will be presented. Itinerary and map of travel route 8:00 Leave convention center 8:20 Arrive to Kerry Park 9:00 Leave Kerry Park 9:45 Arrive to Sammamish Plateau

5 12:15 Leave Issaquah plateau housing development (Alderwood-Everett soils site) 12:30 Arrive to Lake Sammamish (Lunch) 3:30 Leave Lake Sammamish 4:00 Arrive to Mercer Slough (optional stop, time permitting) 4:30 Leave Mercer Slough 5: 00 Return to Convention Center Satellite Image of Seattle area A satellite image [1] of the area we will be visiting is shown on the next page. Refer to the map on this page to identify features. Seattle and its greater metropolitan area

6 The following information on history and development is excerpted from Paul (1987). Seattle is the largest metropolis in the northwestern United States and is the seat of King County, Wash. Seattle is located on a narrow, hilly isthmus between Puget Sound on the west and Lake Washington on the east, and has a population of 516,259 (1990 census) in the area of the city proper and 1,972,961 in the greater metropolitan area. The city is the focal point of a highly urbanized zone that fronts the eastern shore of Puget Sound and incorporates several smaller nearby towns and cities. The central area of Seattle is crowded onto the constricted isthmus, but its suburbs sprawl to the north, south, and east of Lake Washington, which is spanned by two bridges. Spectacular mountains dominate the horizon: the Cascades to the east (with Mount Rainier on the southeast) and the Olympics to the west. Seattle's deep and well-protected Elliott Bay harbor requires no dredging, and it has long been a major Asia-oriented port as well as the principal gateway to Alaska. Its containerized shipping facilities are also among the largest in the world. Since the 1920s, the Boeing aircraft company has been the mainstay of the city's economy. Shipbuilding and the making of wood products are other major industries. Seattle is the home of the University of Washington (1861) and Seattle University (1891). The city has a symphony orchestra, professional theater companies, an opera company, and numerous museums, including the Seattle Art Museum, which in 1991 moved into a new building. Professional football, baseball, and basketball teams are also in Seattle. History The earliest known northwesterners inhabited the Puget Sound Basin since the end of the Pleistocene glaciation, about 10,000 years ago. The native inhabitants had established many villages and subsisted primarily by fishing (Schwantes 1991). Seattle was first visited by Europeans in 1792 by Vancouver and settled by Europeans in Seattle was laid out 2 years later as the seat of King County and named for a friendly Indian chief, Seattle (also called Sealth or See-yat). The city's economy was driven by the timber industry until the 1880s, when the arrival of railroads stimulated economic expansion. Trade with Asia began in the 1890s, and the Yukon gold rush made Seattle an important commercial center. Further stimulus came with the opening of the Panama Canal in A major shipbuilding center during both world wars, Seattle also experienced a boom from aircraft manufacturing during World War II.

7 Geological history of northwest Much of the following discussions are paraphrased and extracted from King County (1987) and Galster and Laprade (1991). The landscape of the Puget Lowland is the product of a long history of mountain-building and subsidence, glaciation and volcanism, erosion and deposition. Agriculture is facilitated by the abundance of water and rich valley soils, while upland soils have provided vast supplies of timber. The valley bottoms and deep-water ports in Puget Sound provide easy transportation routes, while the mountains were barriers in the past. King County encompasses 2,135 sq. miles between the Puget Sound and the crest of the Cascade Range. The most fundamental physiographic divisions are the Puget Lowland and the Cascade Range. The terrain of the Puget Lowland is made up of a series of rolling plateaus cut by steep-sided valleys. The drift plains slope gently west and northwest from the Cascade Range foothills (approx. 800 ft. elevation) to bluffs overlooking Puget Sound; they are built of unconsolidated sediment deposited during glacial and nonglacial periods in the past 2 millions years. The fill ranges from a thin veneer to a depth of 3,600 feet in the deepest basin. The surface features of the drift plains are mostly inherited from the ice sheet that last flowed over them about thousand years ago (Ka): elongate hills (drumlins) are arranged in the direction of ice flow, and marshes and lakes have formed in closed depressions between them and in late-glacial outwash channels. Several large valleys cross the lowlands; the longest and deepest is the Puget Sound. The other valleys are the Lake Washington-Duwamish-Puyallup, Sammamish, and Snoqualmie troughs. All these valleys trend roughly northsouth, likely through preexisting valleys; they are mostly infilled by drift from the most recent glaciation. The trough shapes reflect the direction of ice flow or subglacial rivers in the bottom of the continental glacier. On the other hand, canyons of the Cedar, Green, and White Rivers were excavated by streams flowing from the retreating ice sheet and down from the Cascades. The two types of large valleys have largely controlled postglacial drainage in the lowlands: the rivers flow in them to the large lakes and Puget Sound, and small streams flow to them, carving innumerable ravines in the edges of the plateaus.

8 The Cascade Mountains in the east rise to 3,000 to 9,000 feet and are composed of a variety of bedrock types. In general, the South Fork Snoqualamie River divides the high, rugged North Cascades, made of mostly older metamorphic and intrusive rocks, from the gentler southern Cascades, which are dominantly Tertiary volcanic and sedimentary rocks. Although recent uplift of the Cascades occurred along a north-south axis, a significant secondary topographic grain was formed by older folds and faults that trend northwestsoutheast. The combination of these structural trends controls the pattern of ridges such as the Newcastle Hills, an anticline outlier that plunges westward from Rattlesnake Mountain (3,515 ft.) to Newport Hill (approx. 1,150 ft.). These hills and those around Black Diamond are built of layers of sedimentary and volcanic rocks like those of the southern Cascade foothills. Similar rocks crop out in Renton, Tukwila, Beacon Hill, and Alki Point, and underlie the unconsolidated sediments of the lowlands. Most of the near-surface geologic materials and landforms of King County are quite young. Although the rock of the Cascades are up to approx. 250 million years old (Ma), the present mountain range is no older than 4 Ma, and most of the surface has been altered by glaciation, volcanism, and erosion in the last 20 Ka. None of the surface forms or materials in the lowlands are older than 14 Ka, and some significant portions are less than 6 Ka. These young landforms are not likely to be in equilibrium with respect to geomorphic processes. Continental ice sheets formed in the mountains of British Columbia and flowed into the Puget Lowland several times in the last 2 Ma. Little evidence remains of any of these except the most recent (Fraser) glaciation, which eroded or buried the deposits of previous events. The ice sheet reached its southern limit south of Olympia before 14 Ka and closed off drainage to the north, draining southwest to the Chehalis River. The Puget lobe yielded large amounts of sediment as it advanced, as did rivers and local Cascade and Olympic mountain glaciers.

9 Stratigraphic sequence for the Seattle Area. Time-stratigraphic units denoted by asterisk have not been identified in metropolitan area. Reproduced w ith permission from Laprade and Galster (1991). During the brief maximum glaciation of the Puget Lobe, around Ka, the ice sheet stood about 3,000 feet thick over Seattle. Flowing ice molded the till into elongated drumlins, aligned north-south in the west and northwest-southeast toward the eastern edge of the lowlands, reflecting the varying ice-flow conditions.

10 Physiographic divisions for the King County area of the Puget Low land (reproduced w ith permission from the publisher, Galster and Laprade 1991) Climate and Vegetation Summary Seattle, although infamous for being rainy, receives on average only 890 mm (35 in.) of precipitation annually, with about 75 percent occurring from early October through late March. Snow accounts for less than 5 percent of the precipitation in the Seattle vicinity. The total amount of precipitation, including proportional increases in snowfall, increases to about 1650 mm (65 inches) in the vicinity of North Bend, some 40 km (25 miles) east of Seattle. From North Bend eastward to the crest of the Cascade Mountains the total precipitation increases to approximately 2800 mm (110 inches), with snow making up an estimated 40 percent of the total. This leads to an environment with mild wet winters and warm dry summers. Mean temperature and precipitation for Seattle, WA. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Avg Mean T, F Mean Prec., In A. Marine Division: Willamette-Puget Forest Province (Bailey 1978) 1. Extends North-South along depression between Coast and Cascade Mtn Ranges (Canada to Oregon) 2. Average Elevation 0-1,500 feet throughout Puget lowlands 3. Landforms - floodplains bordered by high terraces and hills, glacial till and outwash, lacustrine deposits 4. Mt. Rainer tallest in Washington at 14,410 ft (others Mt. Adams 12k, Glacier, and Mt. Baker k) 5. Vegetation - "Western Hemlock Zone" (see Vegetation below) B. Dominant Factors Puget Sound Lowlands Weather (Kruckeberg 1991) 1. Semi-permanent High and Low Pressure cells 2. Pacific Ocean - currents, temperature regulation

11 2. Pacific Ocean - currents, temperature regulation 3. Topography/Orographic Effect (Olympics and Cascades) C. Puget Sound Lowlands Climate (Phillips 1970, Jackson & Kimerling 1993) 1. Avg. Annual Temperature Seattle degrees a. Avg. annual range (Jan) to 60.6 (Aug) b. Summer avg. maxima range degrees c. Winter avg. maxima range degrees 2. Avg. Annual Precipitation Seattle inches a. Avg. annual range inches (July) to 5.42 inches (Dec) b. >75% total yearly precipitation between months of October and March c. Avg. annual precipitation as snow in Lowlands inches d. Snow accounts for less 5% total precipitation in Lowland areas 3. Freeze Data - (Average dates over last thirty years at U.W.) 28 degree threshold: 2/04 to 12/13 (240 day growing season) 32 degree threshold: 3/23 to 11/18 (312 day growing season) D. Vegetation Species "Western Hemlock Zone" (Franklin & Dyrness 1973) 1. Dominants a. Tsuga heterophylla (Western hemlock) b. Pseudotsuga menziesii (Douglas fir) c. Thuja plicata (Western red cedar) 2. Sub-dominant Species a. Abies grandis (Grand fir) b. Picea sitchensis (Sitka spruce) c. Pinus monticola (Western white pine) d. Pinus contorta (Lodgepole pine) 3. Hardwoods a. Alnus rubra (Red alder) b. Acer macrophyllum (Big leaf maple) c. Populus trichocarpa (Black cottonwood) d. Fraxinus latifolia (Oregon ash) e. Acer circinatum (Vine maple) Guide to tour stops En route from Convention Center to Queen Ann Hill "[Seattle]... probably represents one of the most infilled, graded, and leveled of all North American Cities" (Galster and Laprade 1991). The relief of Seattle was significantly greater prior to several engineering projects. "Nature apparently grew tired before she finished Seattle. She made a wonderful harbor, produced

12 grew tired before she finished Seattle. She made a wonderful harbor, produced an empire of timber-hung pictures on the horizon, spread three lakes among the hills and then left the town site to itself like a tousled, unmade bed" (by Welford Beaton, 1914, The City That Made Itself cited in Morse, 1989). En route from the convention center to our first stop at on Queen Anne Hill we will drive through an area of Seattle known as the Denny Regrade area. This area represented the epitome of regrading that was done in Seattle. Much of the grading was accomplished by hydrosluicing the sediments in Puget Sound. Photo of Denny Regrade No. 1, The photo below reveals how land ow ners, w ho did not w ant their land regraded, fared. They later had to bear the cost of regrading their ow n property. Stop 1 - Kerry Park, Queen Ann Hill Our first stop is at Kerry Park on the south slope of Queen Anne Hill. This stop provides an opportunity to overlook Seattle, the Duwamish and Green River Valleys southerly from Seattle, the Puget Sound, and several islands westerly from Seattle in the Puget Sound. The geology of Seattle and the Puget lowland physiographic province will be described. Some of the major soil/geology land use concerns will be discussed at this stop. Land use concerns relating to specific soils and geomorphic units will be discussed in more detail at the several stops during the day. Slumping Slumping is mentioned at this stop also since this is a common problem that has been encountered in the Puget Lowland. At this stop we will see one the common problems in the Puget Lowland due to a textural discontinuity between

13 common problems in the Puget Lowland due to a textural discontinuity between basal impermeable layers of either Lawton clay or pre-lawton sediments that are overlain by unconsoliated till or sandy outwash deposits. Typical Seattle conditions, indicating slopes susceptible to slumping (w ith permission from the publisher, Galster and LaPrade 1991). Earthquake hazards It has always been long known that the Puget Sound area is located in an area subject to volcanic and tectonic hazards including earthquakes. It is only recently that a number of new faults have been noted and evidence for much more severe earthquakes in the relatively recent past detected [2]. New evidence for major earthquakes in the past 1,000 years is reviewed briefly during our stop. The series of papers below provide an excellent review of the evidence of these events. En route from Queen Ann Hill to Sammamish Plateau After we leave Discovery Park we will drive along the ship canal and the Ballard Locks; these allow vessels to enter Lake Union and Lake Washington from the Puget Sound and maintain the lake water level above the Puget Sound. After we cross Lake Washington, we proceed east across the Sammamish trough and drive up the Sammamish plateau (this area is better named a drift upland since is not true plateau, but rather is composed primarily of glacial drift). Lake Washington watershed The next few diagrams illustrate how the drainage patterns and lake levels have been altered by the Mountlake Cut and the Ship Canal, canals connecting Lake Washington with Lake Union and Lake Union with the Puget Sound, respectively. Stop 2 - Sammamish Plateau site

14 Our stop on the Sammamish Plateau is at a new housing development. Along an excavated section, two of the most extensive soils in this area, the Alderwood and Everett series, are exposed. Characteristics and properties of these soils and soils that are associated with them will be discussed. Refer to the diagram below for generalized map of soil associations. In the following pages are description and comments regarding the various soils types, and in Appendix 1, the up-to-date SCS soil series description is given. Alderwood Soil Series Loamy-skeletal mixed, mesic Vitrandic Durochrepts Diagnostic Features: vitrandic--volcanic glass + oxalate Al & Fe (0-21"); ochric (0-7"); cambic (7-35"); weakly cemented horizon (35-43") formerly recognized as an ortstein or ortstein fragments; dense till. Soils of the Alderwood series occupy approximately 52 percent of the land area in King County westerly of the mountain front. Alderwood soils are on rolling till plains and moraines; slopes range from 0 to 65 percent. These moderately well drained acidic forested soils formed in loamy glacial till. The Ap horizon is gravelly sandy loam about 7 inches thick. The Bs horizons are gravelly and very gravelly sandy loam about 25 inches thick. A Bsm horizon is a cemented layer that crushes easily to very gravelly sandy loam; about 10 inches thick. The underlying Cd horizon is compact glacial (lodgement) till that breaks with difficulty to very gravelly sandy loam; it is many feet thick. A root mat is common on top of the Cd horizon. Permeability is moderately rapid in the A and B horizons; very slow in the Cd horizon.

15 B horizons; very slow in the Cd horizon. Land Use -- Soil Features, Properties & Constraints Soil features having the greatest influence on use and management: a. Limited rooting depth b. Essentially impervious Cd horizon at depths near 30 inches. c. Dense, extremely hard Cd horizon at depths near 30 inches. The very dense substratum of lodgement till (Cd horizon) provides excellent foundation properties for structures of nearly every size. The essentially impervious substratum causes water to accumulate on it. However, the soils are sloping, so the water moves laterally and remains aerobic. The moving water on top of the lodgement till (Cd horizon) requires conscious action to prevent it from entering basements and crawl spaces of houses and commercial structures. Alderwood soils are not hydric. Prior to the arrival of Europeans, Alderwood soils were covered with forests dominated by western red cedar (Thuja plicata), Douglas fir (Pseudotsuga menziesii), big leaf maple (Acer macrophyllum), red alder (Alnus rubra) and western hemlock (Tsuga heterophylla). Logging of the area made the soils available for grass pastures and urban/residential uses. The restricted rooting depth and numerous rock fragments have been considered obstacles to using these soils for most cultivated crops. The undulating nature of the glacial microtopography contribute to contrasting drainage patterns in landscapes dominated by the Alderwood soil series; they occupy sloping and generally convex parts of the landscape. They occur in intricate patterns with the somewhat excessively drained soils of the Everett series and poorly drained soils of the Norma (Fluventic [Aquandic] Humaquepts) and Bellingham series (Typic Humaquepts), and the very poorly drained Seattle soils (Hemic Medisaprists). Soils of the latter mentioned series occur in depressional parts of the till plain; they are hydric unless drained and generally recognized as wetlands. It is common that the irregular shapes of these bodies of soils (jurisdictional wetlands) and their intricate association with the Alderwood soils pose obstacles to the use of the Alderwood soils: buffers and building setbacks encroach onto the Alderwood soils. Genesis & Classification Problems: The Alderwood series has usually been classified with Durochrepts, but the subgroup has changed at least twice and it was even recently (briefly) classified with Spodosols. Morphological evidence of eluviation (E horizons) is very rare, but B horizons are now officially designated as illuvial (Bs, Bsm) rather than in-situ (Bw). The nature of cementation and the relative importance of compacted lodgment till in the genesis of impermeable subsoils remains controversial. Lodgement in prone to cementation by X-ray amorphous matrix composed of Si, Al, and Fe. Compaction and cementation of the Bsm and Cd horizons The basal, or lodgement, till which underlies the Alderwood is extremely compact (bulk density of 2.0 to 2.2 (Snyder, unpublished data) and, unlike fragipans, does not slake in water. The basal till is apparently cemented and the cementation decreases with depth indicating a leaching mechanism may be important for their genesis. Bracket (1966) determined that the basal till slaked completely in strong acid, but typically not in strong base. McKeague and Sprout

16 completely in strong acid, but typically not in strong base. McKeague and Sprout have studied similar soils in British Columbia and their research indicates that these compacted tills would slake in dithionite > strong acid > strong base, although slaking was incomplete in all these treatments. Their conclusions was that cementation was due to a combination of amorphous materials containing Al, Si, and Fe, although they do not have brown coloration typical of ortsteins. The input of tephra to these soils suggests that this is likely a source of easily solubilized silica, and poorly drained conditions may lead to anoxic conditions that favor reduction and mobilization of iron. Everett Soil Series Sandy-skeletal, mixed mesic Vitrandic Xerochrepts Diagnostic features: vitrandic volcanic glass + oxalate Al & Fe; ochric (0-2"); cambic (2-18") Soils of the Everett series are the second most extensive in King County, making up about 6.5 percent of the soils westerly of the mountain front. Everett soils are on outwash plains, terraces and fans; slopes range from 0 to 65 percent. These somewhat excessively drained acidic forested soils formed in gravelly recessional outwash deposits from mixed lithologic materials. They have very gravelly sandy loam A and B horizons about 20 inches thick that overlay an extremely gravelly 2C horizon. Coarse fragments are mostly subrounded to rounded pebbles and cobbles of mixed lithology. Permeability is moderately rapid in the A and B horizons, and rapid to very rapid in the 2C horizon. Land Use -- Soil Features, Properties & Constraints Soil features having the greatest influence on use and management: a. Low available water supplying capacity. b. Limited rooting depth. c. Extremely gravelly and very gravelly 2C horizon at depths near 20 inches. d. Very rapid permeability rate of the 2C horizon. Vegetative cover, upon the arrival of Europeans, was dominated by Douglas fir (Pseudotsuga menziesii) with lesser amounts of western hemlock (Tsuga heterophylla), red alder (Alnus rubra), and bigleaf maple (Acer macrophyllum). When the timber is removed the soils have been used for pasture, home gardens, and residential and commercial development. The unconsolidated gravelly and extremely gravelly materials make Everett soils very well suited for nearly all buildings: excellent foundation properties and no problems with excess water. Septic tank effluent leach fields frequently require the addition of finer textured soil material under the leach lines, to provide more filtration capacity than available in the extremely gravelly sand of the 2C horizon. When used for landscaping, drought tolerant plants do very well.

17 landscaping, drought tolerant plants do very well. Genesis & Classification Problems: Like the Alderwood the Everett has been reclassified several times, mostly with Ochrepts, but recently and briefly with Spodosols. Since these soils lack cemented and/or compacted subsoils genesis and classification controversy centers on the degree of illuvial (Bs, spodic) versus in situ (Bw, cambic) character of B horizons. Evidence of eluviation is rare for so coarse an acidic forest soil. Some very coarse soils mapped with Everett may lack cambic horizons. Younger Holocene soils may also lack vitrandic properties. Indianola Soil Series Mixed, mesic Dystric Xeropsamments Diagnostic Feature: ochric Soils of the Indianola series make up about 1.3 percent of the land area in King County westerly of the mountain front. Indianola soils are on terraces, terrace escarpments, eskers and kames; slopes range from 0 to about 35 percent. These somewhat excessively drained soils formed in sandy recessional glacial outwash. The B horizon is very friable loamy sand about 25 inches thick. The underlying C horizons are loose sand. Permeability is rapid. Land Use -- Soil Features, Properties & Constraints: Soil features having the greatest influence on use and management: a. Low available water supplying capacity. b. Rapid permeability - excellent drainage for buildings. c. Tendency to slide on steep slopes. d. Excellent foundation strength and stability, for structures, when confined. Indianola soils have been used mostly for woodland and pasture prior to the rise in urbanization rate. In recent years these soils have provided excellent building sites. Genesis & Classification Problems: Indianola soils may show a range in acidity and degree of illuvial properties of B horizons. Their genesis is thought to be similar to Everett and they may share some of the same problems. They are now official recognized with Bw horizons too sandy for cambics. Although not reported in the official series description, weakly cemented lower B and C horizons have been observed areas mapped as Indianola. Norma Soil Series

18 Coarse-loamy, mixed, mesic, Aquandic Humaquepts Diagnostic Features: aquandic properties (0-9"; volcanic ash and oxalate extractable Al + Fe) ochric (0-9"), gleyed cambic (9-28"). Soils of the Norma series make up about 1 percent of the land area in King County westerly of the mountain front. Norma soils are in depressions on the glacial till plain and drainage ways. These poorly drained soils formed in alluvium; slopes range from 0 to 2 percent. The Ap horizon is very dark gray loam about 9 inches thick. The Bg horizon is dark grayish brown stratified sandy loam, gravelly sandy loam or silt loam, about 20 inches thick. The Cg horizon is dark gray stratified sandy loam or loamy sand, generally more than 40 inches thick. Lodgement till, like that underlying the Alderwood soils, occurs at depths near 40 to 50 inches in some places. Land Use -- Soil Features, Properties & Constraints: Soil features having the greatest influence on use and management: Poor drainage; are hydric soils Historically, soils of the Norma series have been used almost exclusively for pastures. The Norma series and a group of similar unnamed "Norma-like soils" are among the most extensive poorly drained mineral soils in the Puget Sound Lowland. Norma soils are deep loamy acidic forest soils formed in local alluvium, drift and volcanic ash in depressions, swales and small drainage ways, mostly in association with Alderwood on drift uplands. The typical pedon has A-Bg-Cg horizonation (Appendix 1), but A-Cg; O-A-Bg-Cg, and other similar horizon sequences are found among the Norma-like soils. Deep A horizons, dark B horizons and weak structure are common. Loams and sandy loams with 0 to 15 percent gravel by volume are the most typical textures. "Norma-like soils" vary from the official series mostly in particle size family (fine-loamy and loamyskeletal classes are common). Genesis and Classification Problems: The Norma series proper is the most common of a group of several similar wet mineral soils. These occur as small to medium sized mappable areas with diverse morphology, and also occur very extensively as inclusions. They are especially common in low relief Alderwood units on drift upland summits ("till plains"). Variations in particle size (family), proportions of volcanic glass, redoximorphic features, and horizonation complicate classification among this group. Geographically associated wet soils include unnamed soils with histic epipedons. Local soil surveys did not recognize any of the transitional somewhat poorly drained soils found in catenas between the wet Norma-like soils and upland soils. Sammamish Soil Series Fine-loamy, mixed, nonacid, mesic Fluvaquentic Humaquepts

19 Diagnostic Features: Ap--0 to 12 inches; very dark grayish brown silt loam, less than 50 percent base saturation; The B horizon is dark grayish brown (2.5Y 4/2), olive gray (5Y 4/2), and grayish brown (2.5Y 5/2) and contains many strong brown (7.5YR 5/6), brown (7.5YR 4/4), dark brown (7.5YR 3/2), and yellowish red (5YR 4/8) mottles. It is stratified silt loam, loam, or fine sandy loam and contains lenses of loamy sand or sandy clay loam. This horizon is slightly acid or neutral. Soils of the Sammamish series make up only about 0.2 percent of the land area in King County westerly of the mountain front. Sammamish was chosen to represent an important group of medium and fine textured mineral soils in valleys and depressions on the glacial till plain. These are deep somewhat poorly drained soils formed in stratified alluvium. The Ap horizon, about 12 inches thick is very dark grayish brown very friable silt loam. The B2g horizons are dark grayish brown, mottled, friable silt loam and loam sand to a depth of about 30 inches. The Bg horizon below 30 inches is olive gray, mottled, very friable fine sandy loam and silt loam. Permeability is moderate to moderately slow. Land Use -- Soil Features, Properties & Constraints: Soil features having the greatest influence on use and management: a. Poor drainage; are hydric soils when undrained. b. Low bearing, compressive strength when wet. c. Suitable for farming and pasture when drained. Sammamish soils were forested when Europeans arrived in the area. They have since been cleared and used for pastures and truck crops. In recent years the desire for centrally located, gently sloping building sites, has brought about the urbanization of some of these soils. In fact, the type location for the series has had fill added to accommodate commercial buildings and access roads. Genesis and Classification Problems: May be mapped in well sorted stratified, delta and lakebed deposits as well as alluvium. Seattle Soil Series Euic, mesic Hemic Medisaprist Diagnostic Features: sapric (0-11"), hemic (11-12"), sapric (12-30"), hemic (30-51") Soils of the Seattle series make up about 1.9 percent of the land area in King County westerly of the mountain front. Seattle soils are in depressions on glacial till plains and in river terraces. These very poorly drained soils formed in organic material derived primarily from sedges. The soil is composed mostly of sapric material but has

20 The soil is composed mostly of sapric material but has thin layers of hemic material in the upper 35 inches; it is mostly hemic material below about 35 inches. Permeability is moderate. Land Use -- Soil Features, Properties & Constraints: Soil features having the greatest influence on use and management: a. Poor drainage; are hydric soils b. Very low bearing, compressive strength. Most Seattle soils have been used for production of berries and truck crops; pastures in a few places. The Seattle series is a deep, very poorly drained organic soil formed in depressions in both river valleys and on drift uplands. The series is only moderately extensive, but is one of the most important Histosols in the Puget Sound Lowland. This and most other important Histosols in the area are composed of moderately to highly decomposed herbaceous and woody plant debris of moderate to very strong acidity. Organic soil material thickness ranges from 51 inches to over 40 feet in this series. Most areas appear to have developed in-situ under a mixture wetland sedge, shrub and forest conditions, but some deposits may have alluvial or exposed lakebed origins. The typical pedon has Oap-Oe1-Oa2-Oa3-Oe2 tiers (appendix 1). These soils are described with mostly highly decomposed muck (Oa, sapric) layers, and some layers of intermediate decomposition state (Oe, hemic) especially at greater depths. The official description does not mention layers of largely undecomposed peat (Oi, fibric), limnic materials (marl) or mineral soil layers within these soils. Stop 3 - Lake Sammamish Park Our next stop is at Lake Sammamish Park. This is our planned lunch stop. On the following page is a map indicating the planned stops. 1. Lunch at the main parking area 2. Wetland site, wetland delineation 3. Laughing Jacobs Stream and influenced by changes in drainage conditions on plateau. 4. Wetland and stream restoration sites. Lake Sammamish Park orientation Soils map of site The area we are visiting is indicated by the square in the soil map (USDA 1973) shown on the next page. The symbols for the mapping units within the study area are given below. Descriptions of these soil series are given in Appendix 1. Key to Soil Map Symbols

21 Key to Soil Map Symbols AkF Alderwood and Kitsap soils, very steep EvC KpD Ma Sh Sk Everett gravelly sandy loam, 5 to 15 percent slopes Kitsap silt loam, 15 to 30 percent slopes Mixed alluvial land Sammamish silt loam Seattle muck Geomorphology of site The diagram below indicates geomorphic consideration for this stop. Our first stop is on alluvium deposited by the inlet stream to Sammamish Lake. The second stop is located at the base of the slope descending from the Sammamish Plateau. The third and fourth stop are intermediate between these. Note the soil associations indicated on the diagram. Wetland function and values Function (ecosystem): Processes that are necessary for the self-maintenance of an ecosystem such as primary production, nutrient cycling, decompositions, etc.

22 an ecosystem such as primary production, nutrient cycling, decompositions, etc. The term is used primarily as a distinction from values. The term values is associated with society's perception of ecosystem functions. Functions occur in ecosystems regardless of whether or not they have values. Values (ecosystem): Values are ecosystem processes or attributes that are valuable or beneficial to society, such as open space, recreation, or cultural heritage. Society make the determination as what is valuable, and values will change, depending on time and circumstance. Riverine Wetland Functions Hydrologic Functions 1. Dynamic Surface Water Storage 2. Long-Term Surface Water Storage 3. Energy Dissipation 4. Subsurface Storage of Water 5. Moderation of Groundwater Flow or Discharge Biogeochemistry/Water Quality Functions 6. Biogeochemical Transformations and Processing 7. Removal of Dissolved Elements and Compounds 8. Retention of Particulates 9. Organic Carbon Export Plant Community Maintenance Functions 10. Maintain Characteristic Plant Communities 11. Maintain Characteristic Detrital Biomass Faunal Community/Habitat Maintenance Functions 12. Maintain Spatial Structure of Habitat 13. Maintain Habitat Interspersion and Connectivity 14. Maintain Distribution and Abundance of Invertebrates 15. Maintain Distribution and Abundance of Migratory, Wide-ranging, Seasonally Resident and/or Resident Vertebrates Definitions of Options for Compensatory Mitigation Kruczynski, 1990.

23 Kruczynski, Wetland Creation: "... the construction of a wetland in an area which was not a wetland in the recent past." Wetland Restoration: "... the re-establishment of a wetland in an area where it historically existed but which now performs no or few wetland functions." Wetland Enhancement: "... increasing one or more of the functions of an existing wetland,... by modifying environmental parameters.... Enhancement implies a net benefit, but a positive change in one wetland function may negatively affect other wetland functions." Stop 4 Mercer Slough This is an optional stop if time permits. The Mercer Slough provides example of organic rich soils and the problems that have arisen at an industrial park that was built here. Appendix 1: SCS soil series descriptions Alderwood Series LOCATION ALDERWOOD, WA, Established Series, Rev. AD/RJE, 4/94 The Alderwood series consists of moderately deep, moderately well drained soils formed in glacial till. Alderwood soils are on glacially modified foothills and valleys and have slopes of 0 to 65 percent. The average annual precipitation is about 40 inches, and the mean annual temperature is about 50 degrees F. TAXONOMIC CLASS: Loamy-skeletal, mixed, mesic Vitrandic Durochrepts TYPICAL PEDON: Alderwood gravelly loam - forested. (Colors are for moist soil unless otherwise noted.) Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) gravelly sandy loam, brown (10YR 5/3) dry; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine roots; few fine interstitial pores; slightly acid (ph 6.2); abrupt smooth boundary. (3 to 7 inches thick) Bs1--7 to 21 inches; dark yellowish brown (10YR 4/4) very gravelly sandy loam, yellowish brown (10YR 5/4) dry; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many fine roots; many fine tubular and interstitial pores; 35 percent pebbles; diffuse smooth boundary; slightly acid (ph 6.2). Bs2--21 to 30 inches; dark brown (10YR 4/3) very gravelly sandy loam, pale brown (10YR 6/3); dry; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; common fine roots; few very fine tubular pores; 40 percent pebbles; slightly acid (ph 6.2); clear wavy boundary. (Bs horizon 15 to 30 inches thick)

24 Bs3--30 to 35 inches; 50 percent olive brown (2.5Y 4/4) very gravelly sandy loam, light yellowish brown (2.5Y 6/4) dry and 50 percent dark grayish brown (2.5Y 4/2) cemented fragments with strong brown (7.5YR 5/6) coatings on fragments, light brownish gray (2.5Y 6/2) and reddish yellow (7.5YR 6/6) dry; massive; slightly hard, very friable, nonsticky and nonplastic; few fine roots; common fine tubular and interstitial pores; 45 percent pebbles; moderately acid (ph 6.0); abrupt wavy boundary. (0 to 15 inches thick) Bsm--35 to 43 inches; dark grayish brown (2.5Y 4/2) cemented layer that crushes to very gravelly sandy loam, light brownish gray (2.5Y 6/2) dry; dark yellowish brown (10YR 4/4), reddish brown (5Y 4/4), yellowish red (5YR 4/8) and strong brown (7.5YR 5/6) in cracks; massive; extremely hard; extremely firm, nonsticky and nonplastic; few fine roots; few fine tubular pores; 40 percent pebbles; moderately acid (ph 6.0); abrupt irregular boundary. (5 to 20 inches thick) Cd--43 to 60 inches; grayish brown (2.5Y 5/2) compact glacial till that breaks to very gravelly sandy loam, light gray (2.5Y 7/2) dry; massive; extremely hard, extremely firm, nonsticky and nonplastic; 40 percent pebbles; moderately acid (ph 6.0). TYPE LOCATION: Snohomish County, Washington; about 5 miles east of Lynnwood on Maltby road; 200 feet south and 400 feet east of the center of sec. 28. T. 27 N., R. 5 E. RANGE IN CHARACTERISTICS: The mean annual soil temperature is estimated to range from 47 to about 55 degrees F. These soils are usually moist, but are dry between depths of 8 and 24 inches for 60 to 75 consecutive days in the summer in most years. The soil is strongly acid to slightly acid above the Bm horizon and slightly acid or moderately acid in the Bm horizon. Depth to Bm horizon is 20 to 40 inches. Rock fragments in the particlesize control section range from 35 to 50 percent and include 0 to 10 percent cobbles. The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist, 3 through 5 dry, and chroma of 2 to 4. It has weak or moderate granular structure. Some pedons have an E horizon less than 1 inch thick. The Bs horizon has hue of 10YR or 7.5YR, and value and chroma of 2 through 6 dry or moist. It is very gravelly loam or very gravelly sandy loam and has weak or moderate blocky structure. The Bs1 is gravelly loam in some pedons. This horizon contains none to many hard concretions presumed to be of iron and manganese compounds. The lower part of the Bs horizon, or the BC or CB horizon has hue of 10YR or 2.5Y, value of 5 through 7 dry, and chroma of 2 through 4 moist and dry. They are mottled in some pedons, but lack mottles of 2 or lower chroma within 30 inches of the surface. These horizons are very gravelly sandy loam or very gravelly loam. They have weak subangular blocky structure or are massive. The Bm horizon (cemented layer) has hue of 10YR or 2.5Y, value of 4 through 8 dry, and chroma of 1 through 3 moist and dry and is mottled in some pedons. It is very gravelly sandy loam, very gravelly loamy sand, gravelly sandy loam, or gravelly loamy sand when crushed. COMPETING SERIES: These are the similar Klaus and Tokul series. Klaus soils are sandy-skeletal. Tokul soils are coarse-loamy. GEOGRAPHIC SETTING: These soils are on till plains and moraines at elevations of 50 to about 800 feet. Slope is 0 to 65 percent. The soils formed in glacial till. Alderwood soils are in a cool marine climate. The summers are cool and dry, and the winters are mild and wet. Average annual precipitation ranges from 25 to 60 inches, most of which falls as rain from November through March. Mean January temperature is 38 degrees F, mean July temperature is 60 degrees F, and mean annual temperature is 50 degrees F. The

25 growing season (28 degrees F) is about 200 days. GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beausite, Dick, Everett, Hoogdal, Indianola, Kitsap, Norma, Quilcene, Skipopa and Whidbey series. All of these soils except Whidbey soils lack a cemented layer within 40 inches. In addition, the Beausite soils have a lithic contact at 20 to 40 inches. Dick, Hoogdal, Indianola, Kitsap, and Skipopa soils have less than 35 percent coarse fragments. Everett soils are sandy-skeletal. McKenna soils have an aquic moisture regime. Norma soils have an aquic moisture regime of less than 35 percent coarse fragments in the upper part of the control section. Quilcene soils are in a fine family. Whidbey soils have an E horizon 2 to 5 inches thick and have a higher base status. DRAINAGE AND PERMEABILITY: Moderately well drained; slow to medium runoff; moderately rapid permeability to the cemented layer and dense glacial till and very slow permeability through them. A perched water table is as high as 1.5 to 3 feet at times from January through March.. USE AND VEGETATION: Woodland, field crops, hay and pasture, orchards, vineyards, wildlife habitat, watershed, and non-farm uses. The native vegetation is Douglas-fir, western hemlock, western redcedar, and red alder with an understory of salal, Oregongrape, western brackenfern, western swordfern, Pacific rhododendron, huckleberry, red huckleberry, evergreen huckleberry, and Orange honeysuckle. DISTRIBUTION AND EXTENT: Northwestern Washington. The series is extensive.. SERIES ESTABLISHED: Snohomish County, Washington REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy. The horizon nomenclature was updated, and fragments of ortstein and ortstein were changed to cemented fragments and a cemented layer. The upper 0 to 21 inches is estimated to meet properties for the Vitrandic subgroup with >5 percent volcanic glass and >0.4 by acid-oxalate extract. Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 7 inches, a cambic horizon from 7 to 35 inches, and a weakly cemented horizon from 35 to 43 inches underlain by dense glacial till. National Cooperative Soil Survey, U.S.A. Everett Series LOCATION EVERETT, WA, Established Series, Rev. DES-RJE, 4/94 The Everett series consists of deep, somewhat excessively drained soils formed in glacial outwash or alluvium with an admixture of volcanic ash on terraces, moraines, and terrace escarpments. Slopes are 0 to 65 percent. the average annual precipitation is about 40 inches. the mean annual temperature is about 50 degrees F. TAXONOMIC CLASS: Sandy-skeletal, mixed, mesic Vitrandic Xerochrepts TYPICAL PEDON: Everett very gravelly sandy loam - forest. (Colors are for moist soil unless otherwise noted.) A--0 to 2 inches; very dark brown (10YR 2/2) very gravelly sandy loam, dark grayish brown (10YR 4/2) dry; weak very fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; many roots; 55 percent pebbles and concretions; medium acid (ph 5.6); clear

26 nonplastic; many roots; 55 percent pebbles and concretions; medium acid (ph 5.6); clear smooth boundary. (1 to 3 inches thick) Bs1--2 to 8 inches; dark yellowish brown (10YR 3/4) very gravelly sandy loam, yellowish brown (10YR 5/4) dry; weak fine subangular sticky structure; soft, very friable, nonsticky and nonplastic; many roots; 55 percent pebbles and concretions; medium acid (ph 5.8); gradual wavy boundary. (5 to 7 inches thick) Bs2--8 to 18 inches; dark brown (7.5YR 3/4) extremely gravelly coarse sandy loam, yellowish brown (10YR 5/4) dry; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic, many roots; 70 percent pebbles and concretions; medium acid (ph 6.0); clear wavy boundary. (0 to 15 inches thick) 2C--19 to 49 inches; olive brown (2.5YR 4/4) extremely gravelly sand, brown (10YR 5/3) dry; massive; loose; 65 percent pebbles; few roots; pale brown (10YR 6/3) manganese stains on underside of pebbles; medium acid (ph 5.8) TYPE LOCATION: Pierce County, Washington; 200 feet west and 200 feet south of NE corner of sec.28, T. 19 N., R. 4 E. RANGE IN CHARACTERISTICS: Mean annual soil temperature is estimated to range from 48 degrees to 54 degrees F. These soils are usually moist, but are dry for 60 to 75 consecutive days in the moisture control section. Reaction ranges from slightly acid to very strongly acid. solum thickness ranges from 13 to 35 inches. The particle-size control section average 35 to 80 percent rock fragments. The A horizon has hue of 10YR to 5YR, value of 2 through 5 moist, and 4 through 6 dry, and chroma of 1 to 3. Some pedons lack an A horizon. The Bs horizon has hue of 10YR or 7.5YR, value of 3 to 6 moist, and 3 through 6 dry, and chroma of 2 to 6. it is very gravelly sandy loam, very gravelly loam, extremely gravelly sandy loam or extremely gravelly loam. The BC horizon, where present, has hue of 10YR or 7.5YR; value of 3 or 4 moist, 4 through 6 dry, and chroma of 3 or 4. it is very gravelly sandy loam, very gravelly loamy sand, or extremely gravelly sandy loam. The 2C horizon has hue of 7.5YR through 2.5Y, value of 2 through 4 moist, and 5 through 7 dry, and chroma of 1 through 4. it ranges from extremely gravelly coarse sand to very gravelly loamy sand. Some pedons are underlain by dense glacial till or glaciomarine sediments. COMPETING SERIES: These are the Barneston and the similar Barnhardt series. Barneston soils are dry in the moisture control section for 45 to 60 days. Barnhardt soils are loamy-skeletal. GEOGRAPHIC SETTING: The Everett soils are on glacial outwash terraces and marginal escarpments at elevations of 30 to 700 feet. Slopes are 0 to 65 percent. These soils formed in alluvium or glacial outwash from granite, quartzite, shale, sandstone, schist, basalt, and andesite with an admixture of volcanic ash in the upper part. The climate is mild, summer is cool and dry, and winter is mild and wet. Mean annual precipitation ranges from 30 to 50 inches. Average January temperature is 36 degrees F., average July temperature is 63 degrees F., and the average annual temperature is 50 degrees F. The average frost-free season ranges from 145 to 210 days. GEOGRAPHICALLY ASSOCIATED SOILS: These are the Alderwood, Baldhill, Indianola, and Kapowsin soils. Alderwood soils have a weakly cemented layer at a depth of 20 to 40 inches. Indianola soils are coarse sandy throughout. Kapowsin soils are coarse-loamy. Baldhill soils are loamy-skeletal.