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71-01 Woodhill SUB PUD pt 2SITE PLAN REVIEW of Wood Hill A Planned Unit Development in Chanhassen, Minnesota Developer McKeon Construction 1550 N.W. Highway Park Ridge, Illinois 60068 (312) 29i-7620 Site Plan Review Requested by: Gerald W. Schlenk for Chanhassen Planning Commission Reviewed by: Donald C. Berg, District Conservationist Robert Lueth, Soil Scientist USDA Soil Conservation Service City Hall Waconia, Minnesota May 24, 1973 In Cooperation With: Carver Soil and Water Conservation District T have reviewed the 83.42 acre proposed Planned Unit Development Plan by McKe, Construction, as submitted to the Carver Soil and Water Conservation District May 15, 1973. This site is planned for 360 patio homes, 12 apartment buildin (with 60, one bedroom and 120, two bedroom apartments) and 9 single family hoi The 83.42 acre property is located in Section 13, Twp. 116N, Range 23W, in th village of Chanhassen. The attached Planned Unit Development Plan has been color coded to show soil ping units and building site limitationss Green has slight limitations Yellow has moderate limitations Red has severe limitations Blue has very severe limitations. Solid colors show land slopes, land alteration, soil erosion and sediment haz limitations. Lined colors show water, wetness, and seepage limitations. The soil mapping units and major building site limitations found on the prope are listed below: Soil Slope Building Site Symbol Soil Name Range Limitations Map Co HaB Hayden loam 2 to 6 % Slight land alteration- Green and soil erosion LaB Lester loam 2 to 6 %, Slight land alteration Green and soil erosion HaC Hayden loam 6 to 12% Moderate land altera- Yelloi tion and soil erosion HaC2 Hayden loam 6 to 12%$ Moderate land altera- Yelloi eroded tion and soil erosion LsB LeSueur clay loam 2 to 6 % Moderate wetness Yellol HaD Hayden loam 12 to 18% Severe land alteration Red and soil erosion Ca Canisteo silty clay loam 0 to 2 % Severe wetness Red L. Cw Cordova and Webster silty 0 to 2 % Severe wetness ed I - clay loams Ge Glencoe silty clay loam 0 to 2% Severe wetness Red L TeB Terril loam 0 to 6 % Severe wetness Red 1: HaE Hayden loam 18 to 257. Very severe land alter- Blue ation and soil erosion HaE2 Hayden loam 18 to 25%0 Very severe land alter- Blue eroded ation and soil erosion HaF Hayden loam 25 to 401/. Very severe land alter- Blue ation and soil erosion Sk Sandy lake beaches 0 to 2 % Very severe wetness Blue . The following is a short description of the soils found on the property and t limitations for building sites, foundations for low buildings, and streets or cost roads. HaB, HaC, HaC2, HaD, HaE. HaE2, HaF The Hayden soils are moderately permeable, loamy soils, over glacial till. T] occupy irregular gently sloping hilltops to strongly sloping hills. The Haydi soils tend to become more impermeable to water with depth; therefore, water ti to seep away slowly on the more level areas. Seepage spots may occur in place the more steeply sloping HaD, HaE, and HaF areas. The major building site limitation is slight landscape alteration and erosion sediment hazard on the B slopes (2 to 6%), moderate landscape alteration and E and sediment hazard on the C slopes (6 to 12%), severe landscape alteration az sion and sediment hazard on the D slopes (12 to 18%), and very severe- landscal teration and erosion and sediment hazard on the E (18 to 25%) and F (25 to 4M slopes. In many Hayden areas, the soil density increases and the permeabilitl creases with depth, and basement seepage can be a common problem. When used as foundations for low buildings, they have a moderate limitation: n shear strength, moderate shrink -swell potential, medium compressibility, medic bearing values, and basement seepage can be a common problem. When used for streets and low-cost roads, they have a moderate shrink -swell pc moderate susceptibility to frost action, moderately fine textured subsoil, anc found on gently sloping to steep topography. The road maintenance problems ir, as the slope increases, especially from erosion and seepage. L aB The Lester soils are well drained loamy soils. The loamy glacial till is coma many feet thick. They occupy 3 to 20 acre irregular, gently sloping hilltops knolls and smooth sloping to steep side slopes. The major building site limitation is slight landscape alteration and erosion sediment hazard on the B slopes (2 to 6%). When used as foundations for low buildings, the limitation is moderate: mediu shear strength, moderate shrink -swell potential, medium bearing values, medium compressibility. When used as streets and low-cost roads, they have a moderate shrink -swell pot moderately fine textured subsoil, moderate susceptibility to frost action, gent sloping to steep topography. L sB LeSueur clay foams are moderately well to somewhat poorly drained loamy sails heavy loam or light clay loam glacial till. The building site limitation is wetness with the seasonal water table at 3 to for short periods. When used as foundations for low buildings, they have moderate limitations; I shear strength, moderate shrink -swell potential, medium compressibility, medil ing values and possible high seasonal water table. When used for streets and low-cost roads, they have a moderate shrink. -Swell p+ teal, moderately fine textured subsoil, and moderate susceptibility to frost ; Cw Cordova and Webster silty clay loamy are poorly drained loamy soils, commonly feet thick, having dark colored surface layers. The major building site limitation is wetness. The Cordova and Webster soils poorly drained and have a high seasonal water table at I to 3 feet. When used as foundations for low buildings, they have a severe limitation: h: seasonal dater table, medium shear strength and bearing values, moderate to h: shrink -swell potential, and medium compressibility. When used for streets and low-cost roads, they have a high seasonal grater tal high susceptibility to frost action$ moderate to high shrink -swell potential, a moderately fine textured subsoil. Ge Glencoe silty clay loamy are very poorly drained clay loam and silty clay loan soils, commonly many feet thick. They occupy I to 5 acre depressions and 5 tc 40 acre long, winding. low gradient drainageways. The major building site limitation is wetness. The Clencee soil is very poor: drainae and has a high seasonal water table that ranges from near the surface a depth of 3 feet. When eased as foundations for low buildings, they have a severe limitation: hi water.table, medium to low shear strength and bearing values, moderates shrink potential, and a medium compressibility. When used for streets and lows -cost roads, they have a high seasonal water tab] are occasionally ponded, and have a high susceptibility to frost action, modei shrink -swell potential, and a moderately fine texture. TeB Terril is mellow, loamy, soils that are dark colored to the 2 to 4 foot depth underlying material is grayish brown or gray loam containing limestone and sh4 fragments. Stones and boulders are common, The high seasonal water table is to 5 foot depth. These soils commonly occur at the base of steep slopes. The major building site limitation is wetness with the water table at 3 to 8 J for short per•i.ods during the season. When used as foundations for low buildings, they have a moderate limitation: shear strength, moderate shrink -swell potential, !tedium compressibility, medic ing values, possible high season water table. When used for streets and low -cast roads, they have a moderate shrink -swell p( medium textured soil, high susceptibility to frost action, possible high seas( • water table and sidehill seepage. Sk Sandy lake beaches are poorly drained sandy materials, commonly about 3 to 5 9 thick over loamy materials. Lake beaches are formed by wave and ice action a: the edges of lake shores and former lake shores and larger peat bogs. -- The major building site limitation is variable flood hazard, depending upon tl levels and variable wetness, depending upon whether adjacent to lakes or drair areas. When used as foundations for low buildings, they have a severe limitation bees of the high seasonal water table unless artificially drained and soil material varies within short lateral distance. When used for streets and low-cost roads, they have a high seasonal water tab] low susceptibility to frost action,, low shrink -swell potential in the.upper 3 5 feet__and are sandy in the upper 3 to 5 feet. For additional soils information$ see "Soil Survey - Carver County, Minnesota" United States Department of Agriculture, Soil Conservation Service,, November ] The soil investigations, mapping and interpretations ordinarily apply to the t 5 to 6 feet of soil, material. There should be additional onsite investigatior sating directly to the proposed uses before construction is started. The following conservation practices should be used by the developer to help the owner and the village the successful and relatively problem free developmE this property. Prepare a conservation plan as an integral part of the site plan that will con soil erosion and keep debris and sediment on the site. This is especially imp tant because the drainage water from this site runs directly into Rice Marsh L Surface water runoff and erosion and sediment control during construction wit a severe problem on the steep (HaD - 12 to 18%, HaE - 18 to 25%, and HaF - 25 slopes. A comprehensive drainage plan, including erosion control practices, temporary and permanent, will be needed. Erosion control practices would app especially to protecting the property along the large gully running North and through the development area. Increased water runoff from building and paved would add to the problem of maintaining stability of the side slopes, edges, bottom of the gully. Grade stabilization practices may be needed to keep the bottom stable and control areas where water enters the gully. The patio homes proposed in the red colored HaD (12 to 18% slope) and blue co HaE (18 to 25% slope) areas would require a great deal of grading and_landsca alteration, and these areas would be exposed to erosion until grass and veget is re-established and retaining walls may be needed. The road grades and cut these areas Would be severe and maintenance would be a continuing problem. When the patio home sites are regraded, temporary sediment and debris `basins be constructed near the lower reaches of drainage ways. Temporary terraces o, diversions may be needed to direct the runoff water from the sloping areas in sediment and debris basins. Top soil should be stockpiled, protected with an anchored straw mulch$ and use later on areas to be stabilized by permanent vegetation. Exposed and eroding areas should be established in temporary vegetation if no built on within 30 days. This seeding should be done immediately following ri grading. The LeSueur (LsB) , Cordova Webster (Cw) , Glencoe (Ge) , Canisteo (Ca)., Terril { and S Wy beach material (Sk) have a high seasonal water table. A drainage p: should -show the sub -surface drainage and/or sump pumps and footing drains that be used to keep the seasonal water table below basement floor levels. in add: the method ofbasement waterproofing should be stated. Permanent vegetation should be established immediately upon completion of fin4 graving on all areas where this is applicable. Complete paving of all designated areas as quickly as possible. Attachedt Development Plan T'ith Soil Mapping Units Colored to Show Building Limitations and Color Key v 4I have reviewed the 83.42 proposed planned unit development by McKeon Construction as submitted to the Carver Soil and Water Conservation Dist on August , 1973. The 83.42 acre property is located in Section 13, Twp 116N, Range 23' in the Village of Chanhassen. I refer the council to the color coded soils map and site review plat prepared for the Chanhassen Plannilg Commission for Building Site Limitat Ratings and descriptions of the soils.} Some questions remain on this pl: f The major objection the Soil and Water Conservation District has to plan is the high amount of grading that will apparently take place when property is developed. This is particularly true on the south end of thl property (blue and red areas on the map). Cuts of 15 to 30 feet or more could well take place on these slopes to grade these soil areas to a grw gentle enough to accommodate the road and patio homes planned. Secondly, how will the erosion and sediment be controlled. Removing vegetation on large areas at one time can cURse erosion with the sedimen- lakeshore, also the ravine which courses diagonally across the property develop into an active gully if sot storm water is not disposed of careft In addition, many of the dwellings appear to be planned to site very the bank of the ravine. Buildings should be kept a safe distance away fi the ravine to prevent reactivation of the gully. Storm water and roof di will have to be carefully disposed of. I would expect that the developer has submitted a (1) grading plan sc a clear picture can be gotten as to the depth of cuts and fills to be mac (2) a plan to dispose of storm water - simply outletting storm water int( ravine can cause reactivation of the erosion process; (3) a plan to cont) erosion to prevent sediment from being deposited on park and open space i particularly at the lower end of the ravine. 4 We would suggest eliminating patio homes on the red and blue soil areas. homes are on steep slopes where deep cuts and fills will be required to the land. The red areas (12-18% slope on the map) might be developed fo terraced housing or other building designs. This soil area can provide architects with a challenge to design and fit buildings to the natural s The upper end of the ravine (HaF), blue on the map, indicates buildings planned for this area. While this can be done the ravine head will need be stabilized. One final statement. The developers comment that groundwater condit are favorable�is not quite true. While the green, yellow, red and blue soil areas (see map) are reasonably dry, soils seepage spots and temporal wetness may occur for a week or so during wet weather. The cross -hatcher soils►'ha e a seasonal watertable that is present only during wet seasons All basements should be waterproofed and footer drains placed around foul ations to prevent basement seepage. o L F th 5 io" r 4 e