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HomeMy WebLinkAbout004-1023-20-000 soil saturation report Safety and Buildings 13 E SPRUCE STREET commercoml.gov CHIPPEWA FALLS WI 54729 RECEIVED TDD (608) 264-8777 ww.commerce.wi.gov/3b! wvww.commerce.wi.gov/sb/ AUG 0 3 www.wisconsin.gov Department of Commerce 2007 Jim Doyle, Governor ST. CROIX COUNTY Mary P. Burke, Secretary January 04, 2007 CUST ID No. 222774 ATTIC- POWTS Building Inspector HENRY F GROTE ZONING OFFICE CERTIFIED SOIL TESTING ST CROIX COUNTY SPIA E4366 353RD AVE 1101 CARMICHAEL RD MENOMONIE WI 54751 HUDSON WI 54016 (Please forward a copy of this letter to the fire, department conducting inspections of this project.) CONDITIONAL APPROVAL PLAN APPROVAL EXPIRES: 01/04/2009 Idenfification Numbers Transaction ID No. 1354177 SITE: Darin Ofstie Site ID No. 721419 Town of Cady, St Croix County Please refer to'both identification numbers,, NE 1/4, S, T~8N, R15W above; in all correspondence With the a gnc . ` Lots: 4 1 , and 1 SubAdiv'is-io1n: P d View Acres FOR: ~L 0/ 57 Object Type: Soil Saturation Determination Regulated Object ID No.: 1112240 The submittal described above has been reviewed for conformance with applicable Wisconsin Administrative Codes and Wisconsin Statutes. The submittal has been CONDITIONALLY APPROVED. The owner, as defined in chapter 101.01(10), Wisconsin Statutes, is responsible for compliance with all code requirements. The following conditions shall be met during construction or installation and prior to occupancy or use: 1. Approval is hereby granted pursuant to s. Comm 85.60(2), Wis. Adm. Code, to estimate the depth to seasonal soil saturation based on an interpretive determination process. Approval of the interpretive determination negates the requirement in s. Comm 85.30(2)(b), Wis. Adm. Code to designate the ground surface as the highest level of soil saturation when redoximorphic features are less than 4 inches below the bottom of the A horizon. 2. The estimated highest level of prolonged soil saturation approved under this determination is 6 inches below grade. At least 30 inches of sand lift on top of 6 inches of unsaturated, in-situ soil is required for adequate treatment and dispersal. 3. The basal soil application rate for the mound shall be < 0.20 gpd/sf, and the linear loading rate 4.0 gpd/ft. 4. Chisel plowing to a depth of 12-16 inches immediately prior to sand placement is required to improve vertical water movement into the soil solurn. 5. Landscaping up slope of the mound shall be incorporated into the POWTS design to prevent surface water from concentrating along the up slope edge of the mound and to divert surface water drainage away from the system. 6. This approval shall remain valid unless the site is altered in such a way that the depth to soil saturation would change or if saturated conditions are observed for seven consecutive days at depths less than 3 feet below the infiltrative surface of the POWTS distribution component. 7. This approval in no way relinquishes the use of color patterns to estimate the depth to high groundwater on any other parcels or portions of parcels. 8. A copy of this approval letter and attachments must accompany the mound system design for this site for purposes of plan approval and sanitary permit issuance. x HENRY F GROTE Page '2 1/4/200'/ Note that lots 14 and 15 were also submitted as part of this review and based on an onsite investigation were deemed not to be acceptable for interpretation of less than A+4 conditions primarily due to shallow land slope, presence or abundance of redoximorphic features and presence of hydrophytic vegetation. Soil saturation monitoring ispursuant to Comm 85.60(3), Wis. Adm. Code is recommended for these lots. If the Interpretive Determination Report was accompanied with a plan and an expiration date is shown on this letter, the expiration date only applies to the plans for the design, not to the decision on the Interpretive Determination Report. A copy of the approved plans, specifications and this letter shall be on-site during construction and open to inspection by authorized representatives of the Department, which may include local inspectors. If plan index sheets were submitted in lieu of additional full plansets, a copy of this approval letter and index sheet shall be attached to plans that correspond with the copy on file with the Department. All permits required by the state or the local municipality shall be obtained prior to commencement of construction/installation/operation. If this construction project will disturb one or more acres of land, an Erosion Control Notice of Intent (NOI) shall be filed with the department 14 days prior to any earth disturbing activities. In granting this approval the Division of Safety & Buildings reserves the right to require changes or additions should conditions arise making them necessary for code compliance. As per state stats 101.12(2), nothing in this review shall relieve the designer of the responsibility for designing a safe building, structure, or component. Inquiries concerning this correspondence may be made to me at the telephone number listed below, or at the address on this letterhead. Sincerely, Fee Required $ 100.00 Fee Received $ 100.00 Balance Due $ 0.00 Leroyy G. ransky, PSS, POWTS Wastewater Specialist Integrated Services Bureau WjSMAR core: `7633 (715)726-2544 Office leroy.jansky@wisconsin.gov r SAFETY AND BUILDINGS DIVISION commerce.wi. ov' Integrated Services Bureau 9 19 East Spruce Street Chippewa Falls, WI 54729 SCD'nSin INSPECTION REPORT www.com 715 .i269-25aa Department of Commerce Date of Inspection: December 19, 2006 Plumber Name and Address: Project Name: Ofstie Property Unknown at this time. Use: Residential Legal Description: NE/NW, SE, 10, 28,15 Site Number: 710037 Subdivision: Proposed Pond View Acres Certified Soil Tester Name and Address: Municipality: Town of Cady Henry F. Grote, CST 222774 County: St. Croix E 4366 353rd Ave Menomonie, WI 54751 Plan Transaction Number: 1354177 Sanitary Permit Number: NA Owner Name and Address: Darin Ofstie Wastewater Flow: 300-600 gpd 2104 Pierce/St. Croix Rd Persons Present: H. Grote Baldwin, WI 54002 (715) 68473299 An onsite soils verification was conducted at the above referenced site as per district policy for all sites with less than four inches of unsaturated soil below the bottom of the A horizon. The intent of this investigation is to confirm initial observations by the certified soil tester (CST) relating to the presence or absence of redoximorphic features in the A horizon and/or subsoil. In-situ soil texture, structure, and consistence factors were also reviewed as they relate to wastewater application rates. Other site conditions such as plant species, percent and direction of land slope, landscape position, land surface contour length, and surface water hydrology may also be noted and their effects are factors considered in the recommendations and conclusions portion of this report. Onsite comments and soil profiles are as follows: Lot 14 - Redosier dogwood and willow - common plants in area. 00-10" 10YR 3/2 sil, 2m-csbk, mfr, cw. 10-12" 10YR 4/3 sil, 2msbk parting to pl, mfr, aw, w/c1f 10YR 4/6 rmfs. 12-24" 10YR 4/4 sil, 2msbk, mfr, cw, w/m2d 7.5YR 5/8 and 10YR 5/2 rmfs (-40% depletions). 24-30" 7.5YR'4/6 sl, Om, mfi, w/c3d 7.5YR 5/8 and 10YR 5/3 rmfs. Lot 15 - Willow - common plants in area. 00-04" 10YR 3/2 sil, 2msbk, mfr, aw. 04-08" 10YR 3/2 sil, 2msbk, mfr, aw, w/c3f 10YR 3/4 rmfs. 08-17" 10YR 4/4 sil, 2msbk parting to pl, mfr, cw, w/c3f-d 104/6 and 5/2 rmfs. 17-27" 7.5YR 4/4 sl, Om, mfi, w/c3d 7.5YR 5/8 and 5/3 rmfs. Lot 16 00-09" 10YR 3/2 sil. 09-18" 10YR 4/4 sil, w/c3f 10YR 4/6 and 5/3 rmfs. 18-28" 10YR 4/4 sl, w/ rmfs. 28-30" 7.5YR 4/4 sl, w/rmfs. Lot 17 00-08" 10YR 3/2 sil, 2msbk, mfr, aw. 08-10" 10YR 5/3 sil, 1csbk, mfr, cw, w/c2f 10YR 4/6 rmfs. 10-20" 10YR 5/3 sil, 1 csbk parting pl, mfr, w/m3d 7.5YR 5/6 and 6/2 rmfs. 20-33" 7.5YR 4/6 sl, Om, mfi, w/c3p 5YR 5/8 and 6/2 rmfs. Lot 18 Pit reviewed had A+>4" conditions. Other pits by CST reported as <4" conditions. r t 1 . Page 2 December 19, 2006 Pond View Acres Additional Comments: It is my opinion, that although the soil conditions observed on lot 14 appear to be without redoximorphic features in the A horizon, the shallow land slope condition, hydrophytic vegetation present in the immediate area, and high percentage of depletions in the subsoil indicate wetter conditions at shallower depths than the observed soil morphology alone indicates. This area may have a depth to seasonal saturation of < 6" for more than 7 consecutive days. On lot 15, redoximorphic features were observed at a depth of 4 inches below the surface. This is similar to conditions observed in April. Hydrophtic vegetation is also prevalent in this area. The high level of redox features and vegetation indicates a greater likelihood that saturated soil conditions (high groundwater) occur at less than 6 inches below grade. Recommendations: Soil saturation monitoring of several lots within the proposed plat is necessary and Lots 14 and 15 should be added to the list of those needing additional evaluation to prove suitable conditions exist. Monitoring pipes should be installed before frost depths make it impossible in anticipation of spring monitoring. In general, mound systems designed to overcome limitations of high levels of seasonal soil saturation and slow permeability need low linear loading rates and should not exceed 4.5 gpd/ft. In addition, the basal wastewater application rated should not exceed 0.2 gpd/ft2. The additional basal area will partially compensate for the gentle land slopes found at most sites and prevent wastewater leakage at the mound toe. At least 30 inches of sand lift is recommended when applying septic tank effluent to the distribution cell of the mound to ensure proper treatment. The longest portion of the mound must be orientated along the contour. The mound shall be constructed to divert surface water around the mound structure as much as possible. In addition, an up slope drainage ditch should be considered if it is determined that surface or subsurface hydrology is improved by intercepting water and diverting it away from the mound site. Where mound sites are near road ditches, the ditch should be made to effectively intercept rain fall and snow melt keeping excessive water from infiltrating near the mound site. If there are any questions regarding this report, please contact me. ekroyj ans ky aste er Specialist cc: ® County ❑ Plumber Ljansk @com rce.stat wi.us E-mail © CST ❑ Owner 715/726-2544 Voice 715/726-2549 Fax ❑ Other i Third Interpretive Determination Report fIECEIVED For A+0" Mound Septic Systems DEC 19 2006 SAFETY & BUILDINGS On the 1354177 Darin Ofstie property LOTS: y, r8 QIJL-( Pond View Acres P.O.W.T.S. Conditionally Proposed Subdivision from part of 30 acres APPROVED DEPARTMENT OF COMMERCE NE 1/4, SE 1/4, Section 10, T 28 N, R 15 )DIVIS ON OF SAFETY AND BUILDINGS DENC And part of the 40 acres in EE CCU~RESP NW 1/4, SE 1/4, Section 10, T 28 N, R,15 W Town of Cady St. Croix County, Wisconsin Submitted by Henry F. Grote, CSTM 222774 Certified Soil Testing, LLC E. 4366 353rd Ave. Menomonie, WI 54751 715-233-0398 Contents Page Introduction 1 Methods 2 Local Hydrology 3 Geomorphology 5 Soil Disturbance and Hydraulic Modification 6 Landscape Position 6 Soil Series 7 Data 9 General Soils Discussion with Conclusions 9 Lot Specific Discussion with Conclusions/Recommendations 12 Lot 4 12 Lot 14 15 Lot 15 18 Lot 16 22 Lot 17 24 Lot 18 27 Lot Summary 31 Attachments Proposed Subdivision Lot Layout, Pond View Acres Aerial photograph, N %2, SE '/4, Section 10, T 28 N, R 15 W Soil Evaluation Reports, Henry F. Grote Topographic Detail, N '/z, SE `/4, Section 10, T 28 N, R 15 W Soil Series Map, N ''/z, SE '/4, Section 10, T 28 N, R 15 W, Soil Survey of St. Croix County i i 4 4 Interpretive Determination Report for A+0" Mound Septic Systems on the Darin Ofstie Property Introduction On December 4-6, 2006, Henry F. Grote, CSTM 222774, Certified Soil Testing LLC, conducted Soil and Site Evaluations on the Darin Ofstie property for the purpose of establishing the potential for onsite wastewater dispersal systems. The preliminary plat for the proposed subdividing describes 28 lots. This report discusses six of those lots which were covered, or partially covered, in the preceding two reports' for this property. Preliminary pits had been constructed ten to seventeen months previous on some lots and more extensive prior work had been done on Lots 4 and 18. These evaluations were conducted on property proposed for subdividing from the thirty acre parcel described as part of the NE '/4 of the SE'/4 of Section 10, T 28 N, R 15 W, and part of the forty acre parcel described as the NW '/4 of the SE'/4 of Section 10, T 28 N, R 15 W. all in. the Town of Cady, St. Croix County, Wisconsin. All of this work followed a preliminary study comprised of twenty-seven soil pits constructed across the described seventy acres including pits constructed in the SW '/4 of the SE '/4 of Section 10, T 28 N, R 15 W.2 Lot 4 is located in the NE-SE quarter-quarter, north of a proposed east west road. Lots 14 through 18 are located in the NW-SE quarter-quarter, around the west end of the proposed east- west road cul de sac. This report will describe general site conditions for the area encompassing the six lots followed by specific lot descriptions and recommendations. Previous evaluations have examined two general areas on lot 4, a "north area" and a "south area." The south area was previously rejected due to a shallow, broad surface drainage feature which impacts the area near the east lot line. Onsite pits in this area indicated questionable soils for a successful A+0" system. The north area was previously rejected due to clay rich sub-soils and onsite pits which indicated questionable soils. At the time of the north area onsite, hand-dug ' Henry Grote, Transaction # 1240465, 3/10/06 and Transaction # 1246796, 4/25/06. 2 Henry Grote, 5/16/05 report of Preliminary pits for proposed subdividing. Y pits near the were satisfactory for an A+0" system. This report will center of the south area propose the use of the south area based on two additional backhoe pits and a shorter system which avoids the questionable area near the east lot line. Previous evaluations have examined lots 14-17 with what could be described as preliminary pits. Additional soils work had been done on lot 18, although a detailed site evaluation was not completed. Previous work on these lots was complicated due to very thick vegetation consisting of dense brush and generally small trees. The proposed platting has extremely limited areas for all lots around the proposed western cul de sac with lot dimensions particularly constrained for lots 15, 16, 17, and 18 along the cul de sac right of way; preliminary plat indications give respective, right of way lengths for these four lots at 65', 57.14', 61.16', and 61.93'. The topographically highest ground, which often is the best landscape position to give the best- drained soil is also around the western cul de sac; by inspection these areas do not allow sufficient lengths along tentative contours to accommodate onsite systems much less onsite systems plus driveway access to the wider, lower portions of the lots. The lot 14-17 area does not have significant topographic relief and appears to be "low ground" with the highest topography of limited area near the cul de sac. The dense vegetation made hand dug pits impracticable and compromised observations due to poor light conditions. During the Wastewater Specialist onsite reflected by Transaction 1246796, two representative backhoe pits were constructed in the lot 14-15 and lot 18 areas which indicated potential for A+0" onsite systems. For the December, 2006 work discussed in this report a D6 bulldozer was used to clear brush ahead of the backhoe used to construct soil pits. The study areas examined were downslope of and offset from the preliminary pits which showed questionable profiles. This report will discuss potential system areas as described by the more extensive soils work under more optimum conditions. Methods Soil color, texture, structure, consistence and redoximorphic features have been evaluated and reported on the accompanying Soil Evaluation Reports in accordance with guidelines under Comm 85 of the Wisconsin Administrative Code. Pertinent information has been abstracted from the Soil Survey of St. Croix County, Wisconsin. Topographic detail has been obtained 2 Y from the DeLorme 3-D TopoQuads CD mapping release. The St. Croix County Land Information Website has been used to retrieve an aerial photograph and soils map, Field investigation included multiple backhoe pits with soil profiles documented on the attached Soil Evaluation Reports. Rod and transit elevations were obtained at pertinent pit locations. The relatively uniform topography allowed slopes to be calculated from pit elevations which allowed the insertion of nominal contour lines on the detailed plot plans. The dense vegetation made impracticable the more typical procedure of obtaining twenty foot grid shots from which detailed contours could be developed. Local Hydrology The major local hydrology input is from annual precipitation. This is estimated at from 29.57 inches3 to 31.5 inches.4 Surface runoff is an additional input most significant during heavy precipitation events. The proposed mound sites and upslope land uses are currently weedy sod ground for Lot 4 and dense brush, small trees. plus some planted pines on Lots 14-18. Lot specific site and upslope descriptions will be provided later in the report within individual lot specific information. Larger scale upslope topography shows a gradual rise to the north-east in the NE t/4 of the NE-SE quarter-quarter. The NE'/4 of the NE-SE quarter-quarter is mostly wooded which will minimize surface runoff downslope to the south and west onto the nearby proposed lots. Due to the convex, nose slope orientation of the proposed site on lot 4, upslope toe landscaping to divert surface runoff around the ends of the systems is the preferred method of minimizing adverse impact on mound performance due to excessive surface drainage. Lots 14-18 suggest very linear orientations for mound systems along the generally parallel contours; for these lots a combination of upslope toe landscaping and occasional subsurface drainage diversion is preferred. Dense glacial till beneath a shallow loess cap provides significant groundwater protection from possible surface contamination. Water outputs consist of surface runoff, soil infiltration, and evapotranspiration. Surface runoff will generally be minimal unless frozen soil conditions or excessively heavy and prolonged J Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p 139. (River Falls, WI data) 4 Wisconsin Average Annual Precipitation (1961-1990), www.crh.noaa.gov/mkx/data/wipcpn.gif 3 t precipitation occurs. Soil infiltration across the studied area varies significantly as the mapped soils vary. Infiltration is described as "somewhat poorly drained" for typical Skyberg series soils5 which comprise the greatest mapped area of the thirty acres in the NE '/4 of the SE 1/4 and extends north into the SW'/4 of the NW-SE quarter-quarter from the SW-SE quarter-quarter. Several specific lots take advantage of the "moderately well drained" Vlasaty silt loam soils6 mapped in the S '/2 of the NW 1/4 of the NE-SE quarter-quarter. Vlasaty Series soils also extend west somewhat irregularly into the east and north central portions plus into the SE 1/4 of the NW- SE quarter-quarter. Additional specific lots take advantage of the "well drained" Arland silt loam soils mapped in the NE'/4 of the NW-SE quarter-quarter; the Arland series mapping slightly extends into the NW '/4 of the NE-SE quarter-quarter. A northeast to southwest tongue of "poorly drained" Auburndale silt loam soils8 is mapped along the drainage way of a Cady Creek tributary located in the NW '/4 of the NW-SE quarter-quarter. A small area of Antigo silt loam is mapped northwest of the Auburndale soils in the extreme northwest corner of the NW-SE quarter-quarte;; due to obvious wetlan d vegetation in an d around the Cady Creek tributary, the areas of Antigo and Auburndale silt loam mapped soils were not explored for this report. A northeast to southwest tongue of "somewhat poorly drained" Magnor silt loam9 soils is mapped paralleling and southeast of the mapped Auburndale soils. A large area of "well drained" Onamia loam10 soils is mapped in the central part of the S 1/2 of the NW-SE quarter-quarter. Described infiltration is reasonable for the typical profiles both described by the Soil Survey and observed in field study pits. The A horizons are all silt loams, occasionally gritty with higher 5 Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p. 57. G Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, 58. Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, 14. Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, 16. Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p. 38. 10 Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p. 40. 4 sand content approaching sandy loams, with higher sand content more common towards the western part of the studied area approaching the mapped Arland and Onamia series. Structure is generally weak to moderate suggesting loading rates of 0.4 to 0.6 gallons per day per square foot for the A horizons. The B horizons are generally weakly structured with textures varying from sandy loams to silt loams Restrictive, massive, clay loam, sandy clay loam, or clay loam till units were very occasionally observed at depths below 14 to 44 inches. The soils described by this report are, in general, markedly less clay-rich than most of the soils observed in the balance of the subdivision. This is attributed to colluvial, erosional deposition from the generally sandy mapped Onamia soil present upslope from lots 14-18 near the center of the S '/2 of the NW-SE quarter-quarter. Restrictive weakly cemented sand rich horizons more common to other subdivision areas were not observed in the current study area. The till units observed at depth were typically massive sandy loam tills rather than sandy clay loam. Slower infiltration is anticipated during wet spring periods when the soils are closer to field capacity and slow to dry. The underlying massive till unit will be significantly restrictive to vertical infiltration. Lateral movement of water through more permeable upper horizons will be somewhat facilitated by the observed cross slopes below proposed contour design lines. Heavy and prolonged precipitation - 2.5 inches in 24 hours; described as once in two years" - will also slow infiltration as the A horizons near field capacity. Evapotranspiration will be a significant factor during the growing season but of no value during the winter season Geomorphology Limestone bedrock underlies most of St. Croix County. Typically the limestone is sandwiched between layers of sandstone which is then overlaid with glacial till forming the principal soil parent material. Rockian till, correlated with the first sub-stage of Wisconsin glaciation, is the parent till for Skyberg and Vlasaty soils. The Arland series soils are significantly influenced by formation from weathered sandstone which is commonly observed at depth in pits nearer the western portions of the studied area. The Onamia soils are formed in pitted outwash and onsite soil pits show significant till influences in and adjacent to the mapped Onamia soils area. The " Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p 140. 5 Cary till, correlated with the third substage of Wisconsin glaciation, is the parent till for the Magnor, Santiago and Freeon soils which are present in smaller percentage of studied areas. Both till units are overlain by a thin concurrent and/or post-glaciation loess cap. The variety of parent materials for the variety of mapped soils in the study area is reflected in the variety and somewhat inconsistency of soil profiles observed in field studies. Soil Disturbance and Hydraulic Modification The proposed mound locations are typically uniform topography. Land use is currently weedy sod across the lot 4 system area and dense brush with small trees across most of lots 14 through 18. A planted pine plantation encroaches into the south-east portion of lot 18 and is present upslope from lot 18 to the crest of the small ridge. Minimal recent tillage and significant root penetration have enhanced soil structure. Planted pines are located in the southern portion of the NW-SE quarter-quarter with some mixed hardwoods on lower ground in the SW corner and brushy wetlands vegetation along the west line and in the NW 1/4 of this quarter-quarter. The upper B horizons and occasionally lower A ho~izons sometimes exhibit platy structure which is a possible artifact of tillage but is as likely a result of the natural deposition process of loess soils. Hydraulic conductivity of the solum can - and should be - improved by deep chisel plowing to a depth of at least sixteen inches. Preliminary site work has modified the natural terrain prior to and is concurrent with the described field work. Prior pond construction has altered site hydrology as has concurrent site road and ditch construction. Concurrent accentuation of natural drainage patterns is expected to improve site drainage. Landscape Position The landscape position of the study area is on the western slope near the midpoint of the west end of a glacial ground moraine. The moraine rises to the east to a nominal elevation of 1270 MSL, just east of 310th St., and just east of the northeast corner of the NE-SE quarter-quarter. Broad scale natural surface drainage is to the west into wetlands, a significant tributary to Cady Creek, and to Cady Creek. Several major surface drainage features are present across the studied seventy acres. A tributary to Cady Creek flows southwest entering the north line of the NW 1/4 of 6 the SE'/4 about 1024 feet east of the NW corner of that quarter-quarter section. This tributary exits the west line of that quarter-quarter section about 1024 feet south of the NW corner at a nominal elevation of 1190 MSL and enters Cady Creek a few hundred feet to the west at a nominal elevation of 1186 MSL. Broad surface drainage is west and south from the high ground located in the northeast corner of the NE 1/4 of the SE '/4. Surface drainage to the south then flows west along a well defined drainage feature closely paralleling the south line of the NE t/4 of the SE '/4. Natural drainage would continue to the west joining Cady Creek a few hundred feet west of the SW corner of the entire SE `/4 of Section 10 at a nominal elevation of 1187 MSL, but drainage now enters a constructed pond located in the NE corner of the SW 1/4 of the SE 1/a at nominal elevation 1206 MSL.12 Any pond overflow will continue to the west to Cady Creek. There is less well defined surface drainage to the west along the north lot lines of both quarter- quarter sections. This surface flow passes through wetlands into the Cady Creek tributary. Typical wetland vegetation is evident along and immediately south of the well defined south line j drainage feature and more broadly evident in the NW 1/4 of the NW-SE quarter-quarter on both sides of the Cady Creek tributary. The southern boundary of platted lots is approximately 145 feet north of the south line of the NW-SE quarter-quarter. A topographic high point is located near the east west center of this quarter-quarter, approximately 300 feet north of the south quarter-quarter line at a nominal elevation of 1222 MSL. Surface drainage is downslope in all compass directions from this point which is near the common lot corners of lots 19, 20, and 21. The high ground land use is a pine plantation which minimizes surface run off in all but extreme precipitation or heavy snow melt events. Soil Series Multiple soil series are present in the studied area as suggested by the above discussions of local hydrology and geomorphology. Nine soil series are mapped across the studied seventy acres; seven series are present in the portion of the proposed subdivision covered by previous reports, with five series representing the soils in the previous study areas. Four soil series are particularly 12 Note that these elevations are taken from the surveyor's plat and differ somewhat in absolute values while not differing in relative differences from the elevations noted in the first report which were obtained from the Delorme topo series of CD's. 7 1 pertinent to the current report for the six studied lots. Proposed system areas are located on one of three mapped Soil series. 13 The Soil Survey of St. Croix County maps the dominant subdivision soils as Skyberg Series. Skyberg is dominant in the north half of the NW 1/4 of the NE-SE quarter-quarter and in the south half of the NE-SE quarter-quarter; Skyberg also has smaller areas mapped in the SE 1/4 and SW 1/4 of the NW-SE quarter-quarter. Vlasaty Series dominates the south half of the NW 1/4 of the NE-SE quarter-quarter and exerts an influence into the central portion and SE 1/4 of the NW-SE quarter-quarter. Arland Series exerts an influence into the west edge of the NW 1/4 of the NE-SE quarter-quarter plus is dominant in the NE V4 of the NW-SE quarter-quarter. The Onamia series occupies the central half of the S 1/z of the NW-SE quarter-quarter while Skyberg is present southwest and southeast of the Onamia soils with Mangor present northwest of the Onamia area. Vlasaty, Magnor and Onamia mapped soils dominate the lots discussed in this report with less area covered by mapped Skyberg series. Auburndale and Antigo series are present in the west central and NW 1/4 of the NW-SE quarter-quarter but these area are not germane to the current report. Field observations of soil pits are generally in reasonable agreement with these mappings although deeper, sand rich horizons were often resistant to penetration due to poor sorting and, perhaps, some weak cementing in the sandy loam tills. Three previous pit profiles obtained in the SW 1/4 of the NW-SE quarter-quarter plus current work on Lot 18 suggest that the mapped Onamia soils do not appear to extend as far west as indicated on soil maps. These pit profiles in what should be almost the east west center of the mapped Onamia soils suggest that the Onamia boundary to the west with mapped Magnor and Skyberg soils is mapped about 300 feet too far west. The gritty nature of many of the observed silt loam horizons in lots 14-18 and the occasional sandy inclusions suggest some downslope erosional deposition from the Onamia soils. Onamia influence on the "somewhat poorly drained" Skyberg and Magnor series soils should improve permeability and the ability of the soils to accommodate onsite mound systems. 13 Vlasaty, lots 4 & 14; Magnor, lots 15, 16, & 17; Onamia, lot 18. 8 The three major series are Alfisols; Families are Fine-loamy, mixed (Arland) and Fine-loamy, mixed, mesic (Vlasaty), and Fine-loamy over sandy or sandy-skeletal, mixed (Onamia). Subgroups are Eutric Glossoboralfs (Arland), Glossaquic Hapludalfs (Vlasaty) and Typic Glossoboralfs (Onamia). The two minor series are also Alfisols; Families are Fine-loamy, mixed (Magnor) and Fine-loamy mixed, mesic (Skyberg). Subgroups are Aquic Glossoboralfs (Magnor) and Udollic Ochraqualfs (Skyberg). The proposed system areas for lots 14-18 take advantage of the "well drained" Onamia influence near the mapped eastern boundaries of the "moderately well drained" Vlasaty and "somewhat poorly drained" Skyberg and Magnor series soils. These study area lots are located in the SW '/4 of the NW-SE quarter-quarter; the lot 4 south study area is located on "moderately well drained" mapped Vlasaty series soils upslope from the mapped "somewhat poorly drained" Skyberg series soils. As noted in the preceding reports for the proposed subdivision, pit profiles show increasing sand content with generally better infiltration as field work progressed from east to west. Parent till subsoil structures are often present as weak and moderate subangular blocky in the west quarter-quarter while the underlying till units-tend to be more commonly massive in the east quarter-quarter. Data The soil and site evaluation report and data are similar to other sites which have received Department of Commerce approvals for A+0" mounds with a minimum of six inches of seasonally unsaturated soils in the upper A horizon. Examples include the previous two reports cited earlier for this subdivision and sites such as the Lisa Mosentine site, ID #636612, Anthony Ludwig site, ID #634143, Jon Mentink site, ID #787909, Tim Holldorf site, ID # 849265, and Karen & Keith Anderson site, ID #639788. General Soils Discussion with Conclusions 1. Seasonally saturated soil conditions do not occur in the upper six inches of the soil profiles of the discussed lots as indicated by the absence of redoximorphic features in the currently described study areas. 9 2. Previous preliminary pits on five lots located near wetlands, near the west boundary of the SW 1/4 of the NW-SE quarter-quarter (lots 14-18) did provide profiles with observed redoximorphic features observed throughout the A horizon (pit 14-2) or as close to the surface as 3-5 inches (pits 15-1, 16-2, 18/19-1 and 18-2), therefore; 3. The current study areas are offset from, generally down-slope of, and avoid these pits. 4. As a group, the six lots with a minimum of six inches of redoximorphic free A horizons are suitable for on-site systems, however; 5. The dense vegetation and uniform, gentle topography require more attention to surface drainage enhancements to minimize potential adverse impact of the surface drainage on proposed mound systems, and; 6. The soil profiles are generally not as promising as the profiles discussed in the second interpretive report where a minimum of seven inches of redoximorphic free A horizons were described, although; 7. One lot 14 has two pits meeting the criteria for A+4" mound systems with limiting factors estimated by observations of redoximgU)hic features at depths of thirteen to twenty-six inches below the surface, while; 8. One lot15 has one pit meeting the criteria for A+4" mound systems with limiting factors estimated by observations of redoximorphic features at depths of fifteen inches below the surface, and; 9. One lot16 has three pits with two to three inches of the upper B horizon free of observed redoximorphic features. 10. The A horizons in the proposed system areas are almost universally Munsell color 7.5YR 3/2, 7.5YR 3/3, and IOYR 3/317 which indicates an organic matter content nominally of less than or equal to 25 g/kg in the range of 20-30 g/kg or 2.5 percent. 18 This level of organic matter is indicative of relatively good drainage and aerobic conditions. 11. The relatively low level of organic matter indicated by the Munsell value of 3 would facilitate observation of high chroma redoximorphic features in the A horizon. The 14 Lot 4. is Lot 18. 16 Lot 17. " 10YR 4/3 and 10 YR 4/4 in pits on Lot 4; 10YR 2/2 in one pit near the surface drainage along the NE lot line of Lot 15 and upslope of the proposed system area.. 18 Tyler presentation, Reading Shallow Soil Saturation, 10/15/04, Ashland UW Ag Research Station. 10 r general lack of observation of these features in the upper six inches of the A horizons is strengthened by the low organic matter content which lends further evidence to a conclusion that at least six inches of soil is present which is not periodically saturated for more than seven days; while 12. Site conditions did allow the observation of redoximorphic features in the lower portions of the A horizon in three pits on lots 18, and two pits on lot 15, and one pit on lot 14; therefore: 13. The fact that redoximorphic features were observed in some pits in portions of the A horizons adds weight to the conclusion that at least six inches of suitable soil are found at proposed site locations on the examined lots. 14. No hydric soil indicators 19 are present in the observed, proposed system area soil pits; this conclusion is based on particularly careful review of the indicators for All Soils and Loamy and Clayey Soils; however 15. Preliminary pits on lots 14-18 (see points 2 and 3 above) meet or approach the criteria for F6 indicator of hydric soils. 16. Root penetration is significantly deep and remarkably consistent across all six lots in the current study with root penetrations to depths of 35 to 42 inches; such depths are not expected in soils which remain saturated for significant time periods. Lot Root Penetration (Inches Observed) 4 18-42 14 24-37 15 22-37 16 25-36 17 25-36 18 28-35 19 Field Indicators of Hydric Soils in the United States, A Guide for Identifying and Delineating Hydric Soils, Version 4.0 (March 1998), p5 ff, 13 ff, & 20 f£; p 16 for F6 indicator. 11 Lot Specific Discussion with Conclusions/Recommendations Lot 4: 1. Previous work examined a tentative system location near the north part of the southern half of lot 4 as preliminarily discussed in the initial report .20 The second report discussed a potential system located on the north half of the lot where a longer contour would allow a lower linear load for a more optimal system. 21 This report will revisit the system area near the north part of the southern half. 2. This area had been chosen due to its proximity to a preliminary pit examined on 5/16/05 which exhibited a reasonable soil profile with marginal A+4" characteristics. The initial area was located immediately south of a brushy, old fence line which has subsequently been removed. The site has a limited length of a potential contour/design line and two of the initial pit profiles showed redoximorphic features in the lower portion of the A horizon which in one profile began just six inches below the surface. Significantly, the general topography of this site is such that a shallow surface drainage feature impinges from the northeast across the eastern edge. of the potential system area. A hand dug pit, near the east portion of the studied area, constructed on October 28, 2005 suggested that there was potential for the redoximorphic features to be within six inches of the surface. Since considerable area remained only partially examined on the north half of the lot, the decision was made to not pursue the initial area at that time. 3. During the spring of 2006 onsite visit by the Commerce, Wastewater Specialist, hand dug pits in the north half area revealed questionable soils for successful A+0" mound systems, but; 4. At that time hand dug pits near the east center of the south area, downslope from a proposed 100.0 design contour were judged satisfactory for an A+0" system, therefore; 5. On December 4, 2006 two additional backhoe pits were constructed, Pits B-9 and B-10; the intent of these pits was to confirm soils away from the questionable east portion of the area and located in the area of the promising hand dug pits constructed in the spring of 2006 during the onsite visit for the second interpretive report. 20 Transaction # 1240465. 21 Transaction # 1246796. 12 6. The proposed system area is located on "moderately well drained" Vlasaty mapped soi1s,22 near the south edge of an east west area of Vlasaty soils which are bordered to the north and south by mapped Skyberg soils. The Vlasaty-Skyberg mapped junctions are approximately 300 feet north and close to the center of the proposed south 100.0 contour/design line. 7. The length of the proposed system area is reduced to the length available from pit B-9 along the 100.0 contour to a point north of B-4; this distance scales to 92 feet. 8. The area discussed in point 5 is best represented by pits 3, 4, 6, 9, and 10. Pit B-5 is outside the proposed area to the east and into the west edge of the shallow surface drainage feature while pit B-3 is upslope of the north end of the 100.0 contour. 9. Seasonally saturated soil conditions do not occur in the upper 8-26 inches of the soil profiles as indicated by the absence of redoximorphic features in the pit profiles of the four pits most representative of the proposed system area. 10. Two of the five representative pits, B-6 and B-10, meet the criteria for A+4" mound systems with upper B horizons free of observed redoximorphic features to depths. of 8-13 inches and 10-26 inches respectively. 11. Pit B-9 horizons commence with Munsell 10YR 4/4 silt loam; this pit is adjacent to or slightly into the old brush line which has been cleared. The clearing process has apparently removed the presumably present, darker, original topsoil. If the original topsoil were present, pit B-9 would also meet A+4" mound systems with an observed redoximorphic free upper B horizon of at least twelve inches. 12. The fact that three of the five representative pits do or would have met the criteria for an A+4" mound adds significant weight to the argument that the site is suitable for an A+0" mound system. 13. In all five of the representative pit profiles the upper B and C horizon redoximorphic features are few and faint or distinct from 8 to 14-58 inches. This suggests; 14. Periodic soil saturation is relatively infrequent and/or short lived throughout the upper 14 inches of the soil profile. zz Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p. 58. 13 15. System area pits demonstrate root penetration to depths of 18-42 inches; such depths are not expected in soils which remain saturated for significant time periods. 16. The small scale cross slopes of 3.5% to 5.0% below the south 100.0 contour as proposed system design line indicate acceptable potential for lateral movement of effluent down- slope into the more permeable upper soil horizons and away from the mound system without surface ponding. 17. The available length which allows for a 75 foot long rock cell gives a low linear loading rate of 4.0 gallons per day per foot for a two bedroom system which enhances the ability of the system to allow effluent to infiltrate the in situ soils. 18. The site is acceptable for a mound septic system with a minimum of six inches of unsaturated soil for treatment and dispersal of treated wastewater effluent as allowed by Comm 83.44(3)(b)1. The observed 8-26 inches of redoximorphic-free natural soil will allow treated effluent to be assimilated into the subsurface without ponding on the ground surface. 19. Upper A horizon silt loam structure, is weak to moderate, granular or subangular blocky, which suggests that the upper eight inches of soil would accommodate loading rates as high as 0.4 to 0.6 gallons per day per square foot, however; 20. Upper B horizon soil structures are weakly platy in two of the pits representing the proposed system area; reorientation via deep chisel plowing is required to reorient any platy structures and improve near surface vertical infiltration, therefore; 21. Site preparation requires mowing and removal of as much vegetation as possible followed by deep chisel plowing to at least a 16 inch depth. 22. Upslope surface drainage onto the proposed site is minimal due to the proposed system location of the south 100.0 contour/design line just south of the north south drainage divide located about thirty feet north of the north benchmark. 23. Additional fill landscaping soil shall be added to the upslope area of the mound structure filling the convex, upslope area between the southeast and northwest system ends. While diversion around both system ends is possible, general topography suggests that diversion to the east around the southeast system end would be more practicable. The final, settled slope of this landscape fill shall be at least 2% to the southeast such that any near-system 14 surface drainage will be diverted around the southeast system end and then downslope to the south. 24. Mound construction requires 2.5 feet of ASTM C-33 sand lift immediately placed on the freshly plowed ground surface. Construction must take place under relatively dry conditions. This depth of sand creates an effective sand filter and can be expected to produce a treated effluent with less than 30 mg/L of both BOD5 and TSS and fecal coliform concentrations of <10,000 cfu/100mL. 25. Site observations indicate that a minimum of 2.33 feet of sand fill is required; however 2.5 feet is recommended to ensure a conservative design and maximize system longevity. 26. The rock cell in the mound structure shall be 4.0' by 75' for a linear loading rate of 4.0 gallons per day per foot for a two bedroom residence. 27. Moderate and weak structured silt loam soils in four of the representative pits to depths of 14-22 inches suggest soil application rates as high as 0.6 to 0.4 gallons per day per square I foot could be accommodated by the upper in situ soils, however; i 28. Pit B-6 soils were textured as fine sandy loams with a weak structure from 2-20 inches which implies loading rates of 0.2 gallons per day per square foot, therefore; 29. The sand basal area loading must be a maximum of 0.2 gallons per day per square foot which can be accomplished by extending the sand toe to 16.0 feet below the lower edge of the rock cell giving a total system basal area loading rate of 0.17 gallons per day per square foot. 30. The system management plan must provide adequate maintenance information to maximize the system longevity. Low 11: 1. The center of the proposed system area is located on "moderately well drained"23 Vlasaty mapped soils, about 75 feet north of the mapped Vlasaty-Onamia junction and about 75 feet east of the mapped Magnor-Vlasaty junction. 2. Seasonally saturated soil conditions do not occur in the upper 7-10 inches of the pertinent soil profiles as indicated by the absence of redoximorphic features. 23 Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p.58. 15 3. Pit B-2, constructed 12/5/05, is located near the cul de sac road ditch in an area which was described as very wet when the road was roughed in. Redoximorphic features throughout the A horizon indicate likely seasonal saturation throughout the A horizon above six inches. The proposed system area begins about seventy-five north of this pit location so the profile is not representative of the proposed system area. 4. The northern third of lot 14 is wetlands along the Cady Creek tributary and is, by observation, not suited for an onsite system. 5. In four of the five pits representative of the system area the upper B horizon redoximorphic features are few and faint or distinct from 7 to 13-15 inches. This suggests: 6. Periodic soil saturation is relatively infrequent and/or short lived throughout the upper 13 inch range of the soil profile, where; 7. Weak silt loam structure indicates the potential for soil loading rates as high as 0.4 gallons per day per square foot for untreated effluent in all representative pit profiles to depths of 15-25 inches, while; 8. Upper A horizon silt loam structure is-typically moderate (3 pits) to weak (2 pits) indicating potential for loading rates between 0.6 to 0.4 gallons per day per square foot of untreated effluent. 9. System area pits demonstrate root penetration to depths of 24-37 inches; such depths are not expected in soils which remain saturated for significant time periods. 10. The small scale cross slopes of 2.9% to 3.1 % below the 99.5 contour as proposed system design line indicate reasonable potential for lateral movement of effluent down-slope into the more permeable upper soil horizons and away from the mound system without surface ponding. 11. Pit profiles indicate a limiting factor at depth of a sandy loam till unit which is not particularly clay rich; the sandy loams at depth give better vertical infiltration potential than the more clay rich sub-soils observed on lots to the north and east of here, however; 12. The upper B horizon subangular blocky structure occasionally parts to a weak, fine platy structure as observed in four of the five representative pits; reorientation via deep chisel plowing is required to reorient any platy structures and improve near surface vertical infiltration. 16 13. Site preparation requires cutting and removal of as much vegetation as possible in a manner which minimizes soil compaction; the site vegetation is very thick brush so careful, thorough brush cutting is required. 14. The available length which allows for a 112.5 foot long rock cell gives a low linear loading rate of 4.0 gallons per day per foot for a three bedroom system which enhances the ability of the system to allow effluent to infiltrate the in situ soils. 15. The site is acceptable for a mound septic system with a minimum of six inches of unsaturated soil for treatment and dispersal of treated wastewater effluent as allowed by Comm 83.44(3)(b)1. The observed 7-10 inches of redoximorphic-free natural soil will allow treated effluent to be assimilated into the subsurface without ponding on the ground surface. 16. As noted above site preparation requires brush cutting and removal of as much vegetation as possible followed by deep chisel plowing to at least a 16 inch depth. Chisel plowing will reorient any platy structures and enhance vertical infiltration. 17. Upslope surface drainage onto the proposed site is minimal due to the road ditch on the south side of the cul de sac and the proposed surface drainage feature to be accentuated along the west lot line. 18. Additional fill landscaping soil shall be added to the upslope area of the mound structure filling the upslope area between the northeast and southwest system ends. While diversion around both system ends is possible, general topography suggests that diversion to the west around the southwest system end would be more practicable. The final, settled slope of this landscape fill shall be at least 2% to the southwest, such that any near- system surface drainage will be diverted around the southwest end to the west and into the surface drainage feature. 19. Mound construction requires 2.5 feet of ASTM C-33 sand lift immediately placed on the freshly plowed ground surface. Construction must take place under relatively dry conditions. This depth of sand creates an effective sand filter and can be expected to produce a treated effluent with less than 30 mg/L of both BOD5 and TSS and fecal coliform concentrations of <10,000 cfu/100mL. 20. Site observations indicate that a minimum of 2.42 feet of sand fill is required; however 2.5 feet is recommended to ensure a conservative design and maximize system longevity. 17 31. The rock cell in the mound structure shall be 4.0' by 112.5' for a linear loading rate of 4.0 gallons per day per foot for a three bedroom residence. 32. Described soil textures and structures indicate that a maximum soils loading rate for the upper one foot of soils is 0.4 gallons per day per square foot, however; 33. The sand basal area loading must be a maximum of 0.2 gallons per day per square foot which can be accomplished by extending the sand toe to 16.0 feet below the lower edge of the rock cell giving a total system basal area loading rate of 0.17 gallons per day per square foot. This will further ensure a conservative design for maximum system longevity. 34. The system management plan must provide adequate maintenance information to maximize the system longevity. Lot 15:1" 1. The center of the proposed system area is located on "somewhat poorly drained"24 Magnor mapped soils, about 150 feet west of the mapped Vlasaty-Magnor junction and about 225 feet northwest of the mapped Magnor-Vlasaty-Onamia junction. 2. Seasonally saturated soil conditions d6 not occur in the upper 6-10 inches of the pertinent soil profiles as indicated by the absence of redoximorphic features. 3. Old pit 15-125 is located near the west edge of the existing shallow surface drainage feature running north of northwest along the nominal east lot line. This pit was originally constructed on December 5, 2005 and common distinct redoximorphic features were observed from 4-8 inches in the lower A horizon. 4. Redoximorphic features throughout the A horizon indicate this pit profile indicates likely seasonal saturation in the A horizon above six inches. The proposed system area begins about twenty-five feet north-west of this pit location, so the profile is not representative of the proposed system area. 5. Pit 15-1 soil profiles fit the description of hydric soil indicator F6 with a matrix color of l OYR 2/2, four inches of moderate silt loam structure which is redoximorphic feature free, and common, distinct redoximorphic features between 4-8 inches in the weakly structured A-2 horizon, and; 24 Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, 38. s Reported as pit B-5 on the current soil evaluation report. 18 6. The upper B horizons in 15-1 from 8-20 inches showed many prominent redoximorphic features, however; 7. At the time of the Wastewater Specialist onsite for the Second Interpretive Report in the spring of 2006 a backhoe pit was constructed in this area and was judged to be marginally suitable for an A+0" mound system, therefore; 8. Additional site work was done on December 6, 2006 beginning with a pit, B-2 approximately 19 feet downslope to the north from the questionable pit old 15-1 (Current 15-5) and following nominal contours twenty-five feet downslope from old 15-1 and offset to the south of southwest towards the lot 16-15 common.lot line. The pertinent representative pits for this are pits 1-4, and; 9. Old pit 15-1 is outside the current study area. 10. As a general note the northern third of lot 15 is wetlands along the Cady Creek tributary and is, by observation, not suited for an onsite system. 11. Pit profiles indicate limiting factors at depth of a more clay rich till unit than the lower clay content sandy loam tills on adjacent lots, this, in combination with the location adjacent to the surface drainage feature, contributes to the observation that; 12. The lot 15 study area is judged to be the wettest study area examined during the December 4, 2006 field work; the two pits at lower elevations showed side seeps of free soil moisture below 30-33 inches. Such side seeps were also observed in old 15-1 at 36 inches the previous December. Pit B-2 was near field capacity below 34 inches, therefore; 13. Soil moisture conditions must be optimal prior to any site work which means strict observation of no site work when upper soil horizons would be wet enough to form a wire rope. 14. In all four pits representative of the system area the upper B horizon redoximorphic features are few and faint or distinct from 6 to 8-14 inches. This suggests: 15. Periodic soil saturation is relatively infrequent and/or short lived throughout the upper eight inch range of the soil profile, where; 16. Weak silt loam structure or sandy loam structure indicates the potential for soil loading rates as high as 0.4 gallons per day per square foot for untreated effluent in all representative pit profiles to depths of 14-24 inches, while; 19 e 17. Upper A horizon silt loam structure is occasional) moderate 1 pit) to weak 3 Y ( p) ( pits) indicating potential for loading rates between 0.6 to 0.4 gallons per day per square foot of untreated effluent. 18. System area pits demonstrate root penetration to depths of 22-37 inches; 26 such depths are not expected in soils which remain saturated for significant time periods. 19. The small scale cross slopes of 2.6% to 3.3% below the 100.0 contour as proposed system design line indicate reasonable potential for lateral movement of effluent down- slope into the more permeable upper soil horizons and away from the mound system without surface ponding. 20. Site preparation requires cutting and removal of as much vegetation as possible in a manner which minimizes soil compaction; the site vegetation is very thick brush so careful, thorough brush cutting is required. 21. The available length which allows for a 112.5 foot long rock cell gives a low linear loading rate of 4.0 gallons per day per foot for a three bedroom system which enhances the ability of the system to allow effluept to infiltrate the in situ soils. 22. The site is acceptable for a mound septic system with a minimum of six inches of j I unsaturated soil for treatment and dispersal of treated wastewater effluent as allowed by Comm 83.44(3)(b)l. The observed 6-10 inches of redoximorphic-free natural soil will allow treated effluent to be assimilated into the subsurface without ponding on the ground surface. 23. Both primary and secondary platy structures were observed in two pits below 10 inches which suggests that deep chisel plowing is required, therefore; 24. As noted above, site preparation requires brush cutting and removal of as much vegetation as possible followed by deep chisel plowing to at least a 16 inch depth. Chisel plowing will reorient any platy structures and enhance vertical infiltration. 25. Upslope surface drainage onto the proposed site is minimal due to the road ditch around the cul de sac and the proposed surface drainage feature to be accentuated along the east lot line. 26. Additional fill landscaping soil shall be added to the upslope area of the mound structure filling the upslope area between the northeast and southwest system ends. While 26 Roots observed to 55 inches in old 15-1 outside the proposed system area! 20 diversion around both system ends is possible, general topography suggests that diversion to the northeast around the northeast system end would be more practicable. The final, settled slope of this landscape fill shall be at least 2% to the northeast, such that any near- system surface drainage will be diverted around the northeast end into the surface drainage feature. 27. Due to observed soil moisture, subsurface drainage is recommended for this site, accordingly; 28. A subsurface drainage shall be installed upslope of the mound system; the drainage shall be an EZ-Flo twelve inch bundle with centered pipe, EZ1201P, installed at an initial depth of 18 inches below grade upslope from the south west system end and laid in a trench with constant I% slope to the northwest upslope from the system terminating in a screened outlet in the surface drainage feature along the east lot line. 29. Mound construction requires 2.5 feet of ASTM C-33 sand lift immediately placed on the freshly plowed ground surface. Construction must take place under relatively dry conditions. This depth of sand creates_an.effective sand filter and can be expected to produce a treated effluent with less than 30 mg/L of both BOD5 and TSS and fecal coliform concentrations of <10,000 cfu/100mL. 30. The rock cell in the mound structure shall be 4.0' by 112.5' for a linear loading rate of 4.0 gallons per day per foot for a three bedroom residence. , 31. Described soil textures and structures indicate that a maximum soils loading rate for the upper one foot of soils is 0.4 gallons per day per square foot, however; 32. The sand basal area loading must be a maximum of 0.2 gallons per day per square foot which can be accomplished by extending the sand toe to 16.0 feet below the lower edge of the rock cell giving a total system basal area loading rate of 0.17 gallons per day per square foot. This will further ensure a conservative design for maximum system longevity. 33. The system management plan must provide adequate maintenance information to maximize the system longevity. 21 Lot 16: 1. The center of the proposed system area is located on "somewhat poorly drained"27 Magnor mapped soils, about 150 feet east of the west lot line, about 270 feet northwest of the mapped Magnor-Onamia-Skyberg junction. 2. Seasonally saturated soil conditions do not occur in the upper 6-11 inches of the pertinent soil profiles as indicated by the absence of redoximorphic features. 3. In three of the four pits representative of the system area the upper B horizon redoximorphic features are few and faint or distinct from 6 to 10-15 inches. This suggests: 4. Periodic soil saturation is relatively infrequent and/or short lived throughout the upper ten inch range of the soil profile, where; 5. Weak to moderate silt loam structure indicates the potential for soil loading rates as high as 0.4 to 0.6 gallons per day per square foot for untreated effluent in all representative pit profiles to depths of 9-24 inches, while; 6. Upper A horizon silt loam structure. is typically moderate (3 pits) to weak (1 pit) indicating potential for loading rates between 0.6 to 0.4 gallons per day per square foot of untreated effluent, however; 7. In pit B-1 a primary, moderate platy structure was observed in silt loam textured soil between 9-12 inches and a secondary, parting, weak platy structure was observed in another pit, B-4, between 11 - 15 inches, therefore; 8. It is essential that a deep chisel plowing is required to reorient these platy structures. 9. System area pits demonstrate root penetration to depths of 25-36 inches; such depths are not expected in soils which remain saturated for significant time periods. 10. The small scale cross slopes of 4.0% to 4.5% below the 98.0 contour as proposed system design line indicate reasonable potential for lateral movement of effluent down-slope into the more permeable upper soil horizons and away from the mound system without surface ponding. 11. Pit profiles indicate a limiting factor at depth of a sandy loam till unit which is only occasionally somewhat clay rich where the texture approaches a sandy clay loam.; the 27 Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p.38. 22 sandy loams at depth give better vertical infiltration potential than the more clay rich sub- soils observed on lots to the north and east of here, however; 12. Site preparation requires cutting and removal of as much vegetation as possible in a manner which minimizes soil compaction; the site vegetation is thick brush and small trees so careful, thorough brush cutting is required. 13. The available length which allows for a 120.0 foot long rock cell gives a low linear loading rate of 3.75 gallons per day per foot for a three bedroom system which enhances the ability of the system to allow effluent to infiltrate the in situ soils. 14. The site is acceptable for a mound septic system with a minimum of six inches of unsaturated soil for treatment and dispersal of treated wastewater effluent as allowed by Comm 83.44(3)(b)l. The observed 6-11 inches of redoximorphic-free natural soil will allow treated effluent to be assimilated into the subsurface without ponding on the ground surface. 15. As noted above, site preparation requires brush and tree cutting and removal of as much vegetation as possible followed by deep chisel plowing to at least a 16 inch depth. Chisel plowing will reorient any platy structures and enhance vertical infiltration. 16. Upslope surface drainage onto the proposed site is minimal due to the road ditch around the cul de sac. 17. Additional fill landscaping soil shall be added to the upslope area of the mound structure filling the upslope area between the northeast and southwest system ends. While diversion around both system ends is possible, general topography suggests that diversion to the west around the northeast system end would be more practicable. The final, settled slope of this landscape fill shall be at least 2% to the northeast, such that any near-system surface drainage will be diverted around the northeast end and downslope to the west. 18. Mound construction requires 2.5 feet of ASTM C-33 sand lift immediately placed on the freshly plowed ground surface. Construction must take place under relatively dry conditions. This depth of sand creates an effective sand filter and can be expected to produce a treated effluent with less than 30 m L of both BODs and TSS and fecal coliform concentrations of <10,000 cfu/100mL. 19. The rock cell in the mound structure shall be 3.75' by 120.0 for a linear loading rate of 3.75 gallons per day per foot for a three bedroom residence. 23 20. Described soil textures and structures indicate that a maximum soils loading rate for the upper nine inches of soils is 0.4 gallons per day per square foot, however; 21. The sand basal area loading must be a maximum of 0.2 gallons per day per square foot which can be accomplished by extending the sand toe to 15.0 feet below the lower edge of the rock cell giving a total system basal area loading rate of 0.17 gallons per day per square foot. This will further ensure a conservative design for maximum system longevity. 22. The system management plan must provide adequate maintenance information to maximize the system longevity. Lot 17: 1. The center of the proposed system area is located on "somewhat poorly drained"28 Magnor mapped soils, about 165 feet east of the west lot line, about 180 feet north of the mapper Magnor-Skyberg boundary and about 210 feet west of the mapped Magnor- Onamia boundary. 2. A preliminary pit, old 16-1, construct6d on December 5, 2005, is located on lot 17 and is reported on the current Soil Evaluation Report as Pit 17-5; the original pit profile was not promising because; 3. Old pit 16-1 soil profiles indicate three inches of moderate structured, redoximorphic free silt loam soil in the A-1 horizon above 3-5.5 inches of moderate structured silt loam soil in the A-2 horizon which had few faint low chroma redoximorphic features. These profiles are close to the technical description of F6 indicators of hydric soils, lacking only not being distinct or prominent redoximorphic features, and; 4. The redoximorphic features within the A horizon indicate likely seasonal saturation above six inches, however; 5. The south end of the proposed 100.0 design contour line is about 40 feet west of the old pit described as 16-1 so the old 16-1 profile is not representative of the proposed system area, and; 28 Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p.38. 24 i 6. Seasonally saturated soil conditions do not occur in the upper 6-11 inches of the pertinent soil profiles as indicated by the absence of redoximorphic features. 7. In the four pits representative of the system area the upper B horizon redoximorphic features are few and faint or distinct from 6 to 10-15 inches. This suggests: 8. Periodic soil saturation is relatively infrequent and/or short lived throughout the upper 10 inch range of the soil profile, where; 9. Weak silt loam structure indicates the potential for soil loading rates as high as 0.4 gallons per day per square foot for untreated effluent in all representative pit profiles to depths of 16-24 inches, while; 10. Upper A horizon silt loam structure is typically moderate (3 pits) to weak (1 pit) indicating potential for loading rates between 0.6 to 0.4 gallons per day per square foot of untreated effluent. 11. System area pits demonstrate root penetration to depths of 25-36 inches; such depths are not expected in soils which remain saturated for significant time periods. 12. The small scale cross slopes of 4.5% to 4.8% below the 100.0 contour as proposed system design line indicate reasonable potential for lateral movement of effluent down- slope into the more permeable upper soil horizons and away from the mound system without surface ponding. 13. Pit profiles indicate a limiting factor at depth of a sandy loam till unit which is not particularly clay rich; the sandy loams at depth give better vertical infiltration potential than the more clay rich sub-soils observed in pit B-5 to the east or on other lots to the north and east of here, however; 14. In pit B-2 a primary, weak platy structure was observed in silt loam textured soil between 8-11 inches and a secondary, parting, weak platy structure was observed in another pit, B-4, between 11-15 inches, therefore; 15. It is essential that a deep chisel plowing is required to reorient these platy structures. 16. Site preparation requires cutting and removal of as much vegetation as possible in a manner which minimizes soil compaction; the site vegetation is very thick brush so careful, thorough brush cutting is required. 25 17. The available length which allows for a 112.5 foot long rock cell gives a low linear loading rate of 4.0 gallons per day per foot for a three bedroom system which enhances the ability of the system to allow effluent to infiltrate the in situ soils. 18. The site is acceptable for a mound septic system with a minimum of six inches of unsaturated soil for treatment and dispersal of treated wastewater effluent as allowed by Comm 83.44(3)(b)l. The observed six to eleven inches of redoximorphic-free natural soil will allow treated effluent to be assimilated into the subsurface without ponding on the ground surface. 19. As noted above site preparation requires brush cutting and removal of as much vegetation as possible followed by deep chisel plowing to at least a 16 inch depth. Chisel plowing will reorient any platy structures and enhance vertical infiltration. 20. Upslope surface drainage onto the proposed site is minimal due to the road ditch around the cul de sac. 21. Additional fill landscaping soil shall be added to the upslope area of the mound structure filling the upslope area between the.north and south system ends. General topography suggests diversion around both system ends is possible. The final, settled slope of this landscape fill shall be at least 2% to the north and/or south, such that any near-system surface drainage will be diverted around the north and/or south ends and then downslope to the west. 22. Mound construction requires 2.5 feet of ASTM C-33 sand lift immediately placed on the freshly plowed ground surface. Construction must take place under relatively dry conditions. This depth of sand creates an effective sand filter and can be expected to produce a treated effluent with less than 30 mg/L of both BOD5 and TSS and fecal coliform concentrations of <10,000 cfu/100mL. 23. The rock cell in the mound structure shall be 4.0' by 112.5' for a linear loading rate of 4.0 gallons per day per foot for a three bedroom residence. 24. Described soil textures and structures indicate that a maximum soils loading rate for the upper 16-24 inches of soils is 0.4 gallons per day per square foot, however; 25. The sand basal area loading must be a maximum of 0.2 gallons per day per square foot which can be accomplished by extending the sand toe to 16.0 feet below the lower edge of the rock cell giving a total system basal area loading rate of 0.17 gallons per day per 26 square foot. This will further ensure a conservative design for maximum system longevity. 26. The system management plan must provide adequate maintenance information to maximize the system longevity. Lot 18: 1. The center of the proposed system area is located on "well drained"29 Onamia mapped soils, about 75 feet north of the south lot line, about 30 feet west of the east lot line and about 180 feet east of the mapped Skyberg-Onamia junction and about 180 feet southeast of the mapped Magnor-Onamia junction. 2. While the proposed system is located on soils mapped as Onamia, as discussed previously, the system location should more properly be described as Onamia influenced soils. 3. Considerable preliminary work had been done on this lot and reported in the second interpretive report on this subdivision,.xecapitulated here; 4. A preliminary pit 18-1 was constructed on 12/5/05, along the common lot line of lots 18 and 19 approximately 120 feet south of the proposed cul de sac right of way and labeled in the field as pit 19/18-1. 5. Pit profiles for pit 18-1 are very similar to profiles for old 16-1 in that four inches of redoximorphic free A-1 horizon were above 4-11 inches of weakly structured silt loam soils which exhibited few faint high and low chroma redoximorphic features. 6. The B horizon profile of pit 18-1 had common distinct redoximorphic features above massive silty clay loam and fine sandy loam sub-soils which both had many and common prominent redoximorphic features. 7. Subsequently, pit 18-2 was constructed about 50 feet west of pit 18-1 on 12/5/05; soil profiles here were similar with few faint redoximorphic features noted below 5 inches in the A-2 horizon above many prominent redoximorphic features observed in massive sub- soils. 29 Soil Survey of St. Croix County, United States Department of Agriculture, Soil Conservation Service, July 1987, p.40. 27 8. The soils map indicates "well drained" Onamia soils extend into the southeast corner of lot 18 about 140 feet from the southeast lot corner upslope from the "somewhat poorly drained" Skyberg soils, consequently; 9. Three additional pits were constructed on February 15, 2006 along and west of the south half of the east line of lot 18; these pits were labeled in the field as 18-2, 18-3, and 18-4. 10. Two of these additional pits (B-2 and B-4) show similar profiles in that A-1 horizons have weakly structured silt loam soils, redoximorphic free to depths of 6 and 8 inches respectively with the A-2 horizons showing few faint to distinct redoximorphic features from 6-10 inches and 8-11 inches respectively, while; 11. Both upper B horizons show common distinct to prominent redoximorphic features from 10-18 inches and 11-22 inches respectively above massive sandy loam horizons with many prominent to common prominent to distinct redoximorphic features to depths of 36 to 42 inches respectively. 12. Pit B-3 soil profiles were marginally suitable for an A+4" mound system in that 10 inches of weakly structured silt loam A horizon which was redoximorphic free was underlain by 10-15 inches of weakly structured silt loam which was redoximorphic free above massive sandy loam horizons which showed few distinct redoximorphic features from 15-26 inches and common distinct redoximorphic features to 26-46 inches, therefore; 13. Pit B-3 had a technical limiting factor of 15 inches and qualified as a A+5" pit, however; 14. Pit B-3 was an upslope, south end pit and pits B-2 and B-4 were downslope pits, with markedly poorer soils in the direction effluent would flow, and; 15. Site conditions were not idea130 to confidently interpret the marginal conditions observed in pits B-2 and B-4; additional soils work was required at that time prior to making a final determination on the prospects for an onsite system on lot 18. 16. Based on these preliminary observations, a third site visit on December 4, 2006 focused on the area closer to the south lot line, south of and down-slope from the most questionable soils reported as B-1 and B-2. This has resulted in four pits being taken as representative of an area suitable for an A+0" mound system with the four pertinent pits being B-3, B-4, B-S- and B-7. 30 Temperatures on February 15, 2006 were near zero with a significant wind chill and several inches of frost was noted in the upper horizons. 28 17. Seasonally saturated soil conditions do not occur in the upper 6-15 inches of the pertinent soil profiles as indicated by the absence of redoximorphic features. 18. In all four pits representative of the system area the redoximorphic features are few and faint or distinct from 6 to 10-15 inches. This suggests: 19. Periodic soil saturation is relatively infrequent and/or short lived throughout the upper 10 inch range of the soil profile, where; 20. Weak silt loam structure indicates the potential for soil loading rates as high as 0.4 gallons per day per square foot for untreated effluent in all representative pit profiles to depths of 11-30 inches, while; 21. Upper A horizon silt loam structure is moderate (1 pits) to more typically weak (3 pits) indicating potential for loading rates between 0.6 to 0.4 gallons per day per square foot of untreated effluent. 22. System area pits demonstrate root penetration to depths of 28-35 inches; such depths are not expected in soils which remain saturated for significant time periods. 23. The small scale cross slopes.of 5.2% below the 100.0 contour as proposed system design line indicate reasonable potential for lateral movement of effluent down-slope into the more permeable upper soil horizons and away from the mound system without surface ponding. 24. Pit profiles indicate a limiting factor at depth of a sandy loam till unit which is not particularly clay rich; the sandy loams at depth give better vertical infiltration potential than the more clay rich sub-soils observed on other lots, however; 27. In pit B-4 a primary, moderate platy structure was observed in silt loam textured soil between 11-22 inches, therefore; 25. It is essential that a deep chisel plowing is required to reorient these platy structures 26. Site preparation requires cutting and removal of as much vegetation as possible in a manner which minimizes soil compaction; the site vegetation is some brush, small trees, and some planted pines, so careful, thorough brush cutting is required. 27. The available length which allows for a 120 foot long rock cell gives a low linear loading rate of 3.75 gallons per day per foot for a three bedroom system which enhances the ability of the system to allow effluent to infiltrate the in situ soils. 29 28. The site is acceptable for a mound septic system with a minimum of six inches of unsaturated soil for treatment and dispersal of treated wastewater effluent as allowed by Comm 83.44(3)(b)l. The observed six to fifteen inches of redoximorphic-free natural soil will allow treated effluent to be assimilated into the subsurface without ponding on the ground surface. 29. As noted above site preparation requires brush and tree cutting with removal of as much vegetation as possible followed by deep chisel plowing to at least a 16 inch depth. Chisel plowing will reorient any platy structures and enhance vertical infiltration. 30. Upslope surface drainage onto the proposed site is minimal due to the entire upslope being heavily wooded with a pine plantation. 31. Additional fill landscaping soil shall be added to the upslope area of the mound structure filling the upslope area between the north and south system ends. While diversion around both system ends is possible, general topography suggests that diversion to the south around the south system end would be more practicable. The final, settled slope of this landscape fill shall be at least 2% to. the south, such that any near-system surface drainage will be diverted around the south end then down-slope to the west. 32. Mound construction requires 2.5 feet of ASTM C-33 sand lift immediately placed on the freshly plowed ground surface. Construction must take place under relatively dry conditions. This depth of sand creates an effective sand filter and can be expected to produce a treated effluent with less than 30 mg/L of both BOD5 and TSS and fecal coliform concentrations of <10,000 cfu/100mL. 33. The rock cell in the mound structure shall be 3.75' by 120.0' for a linear loading rate of 3.75 gallons per day per foot for a three bedroom residence. 34. Described soil textures and structures indicate that a maximum soils loading rate for the upper 11-30 inches of soils is 0.4 gallons per day per square foot, however; 35. The sand basal area loading must be a maximum of 0.2 gallons per day per square foot which can be accomplished by extending the sand toe to 15.0 feet below the lower edge of the rock cell giving a total system basal area loading rate of 0.17 gallons per day per square foot. This will further ensure a conservative design for maximum system longevity. 30 36. The system management plan must provide adequate maintenance information to maximize the system longevity. Lot Summary: Lot # bedrooms Rock cell Linear Load Comment (ft) (gal/ft) 4 2 4 x 75 4.0 Recommend 14 3 4 x 112.5 4.0 Recommend 15 3 4 x 112.5 4.0 Recommend 16 3 3.75 x 120 3.75 Recommend 17 3 4 x 112.5 4.0 Recommend 18 3 3.75 x 120 3.75 Recommend All sand toes extended downslope to give a minimum of 0.2 gallons per day per square foot of sand basal area loading. Final authority for this site's approval rests with the appropriate regulatory authorities, the Wisconsin Department of Commerce and the St. Croix County Zoning Office. This report, conclusions and recommendations are the professional opinion of Henry F. 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