Planning Commission

Spearfish Planning Commission Agenda 06Sep22 at 3:00 p.m. Meeting Location: City Council Chamber, 625 Fifth Street, Spearfish, SD And Zoom Online Meeting Join Zoom Meeting https://us02web.zoom.us/j/88567070608 Meeting ID: 885 6707 0608 Or Dial in: 06Sep22 at 3:00 p.m. and enter Meeting ID A. Call To Order B. Roll Call C. Approve the Minutes from 02Aug22 D. Declaration of Conflicts of Interest E. Items for Action 1. Request: Discuss development option for Highway 85 corridor Location: City Council chambers, 625 5th Street, Spearfish SD Applicant: N/A Action: Request motion from Planning Commission on how to proceed F. City Council Update G. Public Comment: Public comments are welcome at this time; however, no action will be taken H. Adjournment  Spearfish Planning Commission Regular Session Minutes 02Aug22 at 3:00 p.m. The Spearfish Planning Commission met in regular session on Tuesday, 02Aug22 at 3:00 p.m. in the council chamber of city hall and via Zoom video conference. Meghan Byrum called the meeting to order at 3:00 p.m. Roll call was taken with the following members present: Meghan Byrum, Toby Bordewyk, Bob Meyer, Rick Tysdal, and Barbara Zwetzig; absent Greg Kruskamp and Larry Vavruska. Also present: Planning Director Nick Broyles, Mayor John Senden, City Administrator Steve McFarland, City Attorney Ashley McDonald, and Administrative Assistant Erica Bussiere. APPROVAL OF MINUTES Zwetzig moved, Meyer seconded, and all voted to approve the minutes of the 19Jul22 Planning Commission meeting. DECLARATIONS OF CONFLICTS OF INTEREST Byrum called for any potential conflicts of interest to be identified. No conflicts were expressed. Broyles introduced Rick Tysdal via a short biography, and Commissioner Tysdal addressed the Board. 1. Request: Discuss Development Options for the Highway 85 Corridor Location: City Council Chamber, 625 Fifth Street, Spearfish, SD Applicant: Action: Request Motion from Planning Commission on How to Proceed Broyles and City staff presented findings for questions posed by the Planning Commission on 19Jul22. Findings are articulated in the 02Aug22 agenda: (1) options for de-annexation – how is it initiated/approved; (2) ordinance 15A compels connection to city services to subdivide; can a property have septic without subdividing? Does it matter if it is zoned AG or C2? (3) can “special permitted uses” allow for septics/wells on AG and/or C2? Does it matter if it is subdivided or not? (4) discuss engineering of septic systems with the result of quantifying septic requirements, and possibly approving on a case-by-case basis; (5) through “special permitted uses”, can commercial activities be permitted on AG? Staff recommended one of two options: (1) recommend City Council to continue to require development to occur within the parameters of existing code and annexation agreement, or (2) recommend City Council direct staff to explore changes to current ordinances to facilitate development through alternative means. Zwetzig made a motion and Meyer seconded to direct staff to develop high-level, big-picture bullet points to define general requirements, with particular emphasis on risk, simplicity, and flexibility for the following three items: (1) Actual “special permitted uses” language across appropriate zoning districts that would address septic systems, or onsite sewage disposal. Commission suggested something similar to the “conditional use permit” language – perhaps where specific questions need to be answered by applicant (2) Proposed language edits of Chapter 15A of the code (subdivision) to align with “special permitted uses” from item 1 (3) At a big picture level, explore a methodology for quantifying risks associated with septic systems The motion passed unanimously with no Commissioner dissent. Spearfish Planning Commission Regular Session Minutes Page 2 2. City Council Update: Broyles provided an update on the Elkhorn Ridge Lift Station A & B bid letting and award. The bid came in at ~1% over engineer’s estimate. Elkhorn and KLJ recommended awarding the contract to Mainline Construction and City Council concurred. Broyles also provided an update on the Exit 8 Community Path Project. Bids came in at ~56% over engineer’s estimate. The bid was rejected. Lastly, Broyles informed Commission that Council and Staff are currently in 2023 budget discussions. 3. Public Comment: Public comment was provided by Joe Jorgenson. 4. Adjournment: Byrum adjourned the meeting at 4:35 PM.  Spearfish Planning Discussion Item 06 September 2022 at 3:00 p.m. TO: Planning Commission FROM: Nick Broyles, Planning Director RE: Discussion of Highway 85 Development ATTACHMENTS: NRCS Soils Survey State Requirements for Septic Design From the 02Aug22 Planning Commission meeting, staff was requested to provide general requirements associated with Special Permitted Uses (SPU) in the Highway 85 corridor. The Commission noted that concepts should be considered with the following in mind: risk mitigation, simplicity, and flexibility. Staff was requested to evaluate three main topics. 1. Potential land uses eligible as SPU with onsite sewage treatment along with criteria to guide 2. Potential changes in the subdivision code to mirror the SPU sewage treatment requirements 3. Methods to quantify/ID risk associated with septic/drain fields For the purposes of this document, the below terms are defined as follows: Septic a system that separates solids and liquids and is not connected to any other treatment system or city sewer Private Treatment Plant a system that collects wastewater from multiple points and cleans it up before discharge - these are not connected to the City sewer system when built 1. Potential Special Permitted Land Uses and Criteria The protection of ground water undergirds this entire document. It is important to identify common land uses ranging from low to high sewer flows. Some key considerations are (1) the lower the sewer flow, the more likely it can be served by septic, and (2) the higher the sewer flow, the more likely it must be served by a private treatment plant. The below land use list could be coupled with a maximum sewer flow measured in gallons per minute (GPM) to determine what is eligible for special permitted use using either septic or a private treatment plant. Land Uses The following are examples of likely SPUs and their relative sewer flow measured in GPM. These could be added as Special Permitted Uses to AG, C-2 Highway Service Commercial, Light Industrial, and Heavy Industrial zoning districts. The dashed line below represents a likely cut off point for what would require an onsite plant and is provided simply for visualization purposes. 1. Storage buildings without indoor plumbing fixtures 2. Outdoor parking for RV’s, trucks, and equipment 3. Manufacturing, workshops, fabricating businesses Lower Sewer Flow 4. Repair services 5. Retail of any type - septic permitted 6. Office and personal services - designed to State 7. Convenience store with gas station standards Higher Sewer Flow 8. Restaurants and beverage services 9. Single family subdivision - private treatment 10. Multi-Family apartment building plant required 11. Medical clinic - designed to State 12. Hotel standards 13. Nursing home 14. Hospital Criteria for Special Permitted Uses SPU criteria must be objective and easily determined because it is a staff level of approval and requires no public hearing; possible criteria for SPUs follow. - Septic permitted up to a maximum amount of sewer GPM; all else must be private treatment plant (staff will research the threshold point) - Minimum lot size is 8 acres for lots served by septic systems - Minimum lot size is the standard per the zoning district for lots served by private treatment plants  - Owner’s design engineer must submit plans that comply with state design criteria for all systems - Owner must agree to connect to city sewer when available - Owner must comply with all other terms of the subdivision code 2. Changes to the Subdivision Code to Reflect SPUs The required changes to Chapter 15A are straightforward, and as noted by the underlined text. For consistency and improved readability, changes to the AG provisions for septic have been reformatted to match paragraph for septic have been reformatted to match paragraph b. Sec. 15A-95. Water and Sewer Facilities (a) Except where otherwise provided in the following paragraphs, the subdivider is required to connect to the municipal water and sewerage systems and must install all facilities according to the specifications of the public works department. Service lines must be stubbed to every lot abutting a street prior to the surfacing of the street. (b) For lots zoned Rural Large Lot Single Family (RLS-1), and Special Permitted Uses in the AG (Agriculture), C-2 (Highway Service Commercial), I-LR (Light Industrial), and IH (Heavy Industrial) zoning districts, private/shared wells and private sewage disposal systems are permitted according to the following criteria. i. Septic systems are permitted when maximum sewer flow of the entirety of the subdivision is (number) or less GPM ii. Private sewage treatment plants are required when maximum sewer flow of the entire subdivision is (number) or less GPM iii. The distance from the overall boundary of the subdivision to the nearest city sewer or water main must be 200 feet or more iv. All design of the above must be stamped and sealed by a licensed Professional Engineer v. Conflicts between the above criteria and a more restrictive law or regulation will result in the application of the more restrictive rule (c) For lots one (1) acre and larger, but less than eight (8) acres, and zoned Agriculture (AG), private sewage disposal systems are permitted according to the following criteria. i. The distance from the overall boundary of the subdivision to the nearest city sewer main by gravity flow must be 200 feet or more ii. Connection to the municipal water system is required iii. All design of the above must be stamped and sealed by a licensed Professional Engineer iv. Conflicts between the above criteria and a more restrictive law or regulation will result in the application of the more restrictive rule 3. Methods to Identify & Quantify Risks with Septic / Drain Fields Attached to the staff report is data published by the Natural Resource Conservation Service concerning suitability of septic systems in the Highway 85 area. This is a starting point to identify locations where the existing conditions are not suitable to a traditional septic design; key considerations follow. (a) Example: map and data indicate slow water movement through soil profile; engineer must account for that in the septic design so that it meets the required percolation rates in the state standards (b) Risk managed in design through compliance to State standards (c) Risk managed after construction requires inspection program which has not received the support of City Council for the city to develop this kind of program If the Planning Commission seeks to strengthen the input/design side of the process (mapping with supporting technical guidance), it will require the help of a consultant as City staff does not have the needed expertise in soils/geology as it relates to septic design that would go beyond state regulations. Staff requests that the Commission confirm if any of the below should be initiated, and this will be shared with City Council who will make the final determination to proceed since funds need to be budgeted and the (1) review of existing mapped and written data and create a risk assessment system for septic systems, (2) review existing state standards in septic design for potential gaps based on new assessment system, and (3) develop new standards for septic design and methods to enforce via the inspections process. 4. Conclusion The Planning Commission requested staff to consider recommendations through the lenses of risk mitigation, simplicity, and flexibility. Staff comments relative to the three follows. Risk Requires assistance of a consultant to develop a system, and City Council must also concur that this is a desired effort. Simplicity Developing a list of Special Permitted Uses to be added to the suggested zoning districts will enable a quick determination by both staff and the public of what land uses are allowed. Criteria for the corresponding wastewater treatment solution is objective and appropriate for staff level of approval. Flexibility Property owner may weigh out options for how to market or develop their property. This avoids a one-size-fits all solution and supports reasonable development in advance of the extension of city infrastructure. Lower impact uses would be permitted septic with higher impact uses needing private treatment plants. ADA Compliance: The City of Spearfish fully subscribes to the provisions of the Americans with Disabilities Act. If you desire to attend this public meeting and need special accommodations, please notify the Building and Development Office at 642-1335 and 24 hours prior to the meeting so that appropriate auxiliary aids and services are available.  103° 53' 47'' W 103° 48' 35'' W Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota 588000 589000 590000 591000 592000 593000 594000 4939000 44° 35' 54'' N 44° 35' 54'' N 4938000 4938000 4937000 4937000 4936000 4936000 4935000 4935000 4934000 4934000 4933000 4933000 4932000 4932000 4931000 4931000 4930000 44° 30' 59'' N 4930000 44° 30' 59'' N 588000 589000 590000 591000 592000 593000 594000 103° 53' 47'' W 103° 48' 35'' W Map Scale: 1:44,300 if printed on A portrait (8.5" x 11") sheet. Meters N 0 500 1000 2000 3000 Feet 0 2000 4000 8000 12000 Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 1 of 14  Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota MAP LEGEND MAP INFORMATION Area of Interest (AOI) Background The soil surveys that comprise your AOI were mapped at Area of Interest (AOI) Aerial Photography 1:24,000. Soils Please rely on the bar scale on each map sheet for map Soil Rating Polygons measurements. Very limited Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Somewhat limited Coordinate System: Web Mercator (EPSG:3857) Not limited Maps from the Web Soil Survey are based on the Web Mercator Not rated or not available projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Soil Rating Lines Albers equal-area conic projection, should be used if more Very limited accurate calculations of distance or area are required. Somewhat limited This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Not limited Soil Survey Area: Butte County, South Dakota Not rated or not available Survey Area Data: Version 25, Sep 13, 2021 Soil Rating Points Soil Survey Area: Lawrence County, South Dakota Very limited Survey Area Data: Version 24, Sep 13, 2021 Somewhat limited Your area of interest (AOI) includes more than one soil survey Not limited area. These survey areas may have been mapped at different scales, with a different land use in mind, at different times, or at Not rated or not available different levels of detail. This may result in map unit symbols, soil Water Features properties, and interpretations that do not completely agree across soil survey area boundaries. Streams and Canals Soil map units are labeled (as space allows) for map scales Transportation 1:50,000 or larger. Rails Date(s) aerial images were photographed: Sep 18, 2021—Oct Interstate Highways 16, 2021 US Routes The orthophoto or other base map on which the soil lines were Major Roads compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor Local Roads shifting of map unit boundaries may be evident. Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 2 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Septic Tank Absorption Fields Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) P028A Barnum silt Somewhat Barnum, rarely Slow water 52.7 2.2% loam, moist, 0 limited flooded (80%) movement to 2 percent (0.50) slopes, rarely flooded Depth to saturated zone (0.43) Flooding (0.40) Rockypoint, Slow water rarely flooded movement (5%) (0.82) Flooding (0.40) Sodawells, rarely Flooding (0.40) flooded (4%) Subtotals for Soil Survey Area 52.7 2.2% Totals for Area of Interest 2,358.1 100.0% Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) P008B Alice fine sandy Very limited Alice, moist Seepage, bottom 103.1 4.4% loam, moist, 0 (90%) layer (1.00) to 6 percent slopes Slow water movement (0.08) Recluse, moist Slow water (5%) movement (1.00) P024A Barnum silt Very limited Barnum, moist, Flooding (1.00) 71.3 3.0% loam, moist, 0 occasionally to 2 percent flooded (80%) Slow water slopes, movement occasionally (0.50) flooded Depth to saturated zone (0.43) Sodawells, Flooding (1.00) occasionally flooded (4%) Rapidcreek, Flooding (1.00) poorly drained (1%) Depth to saturated zone (1.00) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 3 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) Seepage, bottom layer (1.00) P032E Barnum, moist, Very limited Barnum, moist, Flooding (1.00) 46.1 2.0% occasionally occasionally flooded- flooded (31%) Slow water Tilford-Nevee movement silt loams, 1 to (0.50) 25 percent Depth to slopes saturated zone (0.43) Nevee (25%) Slope (1.00) Depth to bedrock (0.85) Slow water movement (0.82) Spearfish (5%) Depth to bedrock (1.00) Slope (1.00) P152D Gypnevee- Very limited Gypnevee, moist Slope (1.00) 61.3 2.6% Rekop silt (35%) loams, moist, Depth to bedrock 6 to 25 (0.91) percent slopes Slow water movement (0.50) Gypnevee, Slope (1.00) moist, very deep (25%) Slow water movement (0.50) Rekop, moist Depth to bedrock (25%) (1.00) Slope (1.00) P158C Herdcamp, Very limited Herdcamp, Flooding (1.00) 72.4 3.1% somewhat somewhat poorly poorly drained Depth to drained- (40%) saturated zone Herdcamp- (1.00) Tilford Slow water complex, 1 to movement 10 percent (0.68) slopes, flooded Herdcamp, Flooding (1.00) poorly drained (30%) Depth to saturated zone (1.00) Slow water movement (0.68) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 4 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) Barnum, moist, Flooding (1.00) occasionally flooded (5%) Slow water movement (0.50) Depth to saturated zone (0.43) Ustifluvents (3%) Flooding (1.00) Slow water movement (0.50) P160A Higgins silt loam, Very limited Higgins (80%) Flooding (1.00) 13.4 0.6% 0 to 2 percent slopes Depth to saturated zone (1.00) Slow water movement (0.68) Higgins, Depth to somewhat saturated zone poorly drained (1.00) (5%) Slow water movement (1.00) Flooding (0.40) Barnum, moist, Flooding (1.00) occasionally flooded (5%) Slow water movement (0.50) Depth to saturated zone (0.43) Higgins, very Flooding (1.00) poorly drained (5%) Ponding (1.00) Depth to saturated zone (1.00) Slow water movement (1.00) P246B Nevee silt loam, Somewhat Nevee (85%) Depth to bedrock 129.2 5.5% 2 to 6 percent limited (0.85) slopes Slow water movement (0.50) Tilford (7%) Slow water movement (0.82) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 5 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) Vale (5%) Slow water movement (0.82) P256D Nevee-Spearfish Somewhat Nevee (60%) Depth to bedrock 79.7 3.4% silt loams, 6 to limited (0.85) 20 percent slopes Slow water movement (0.82) Slope (0.63) Tilford (7%) Slow water movement (0.87) Nevee, very Slow water deep (3%) movement (0.82) Slope (0.16) Gypnevee, moist Depth to bedrock (2%) (0.91) Slope (0.63) Slow water movement (0.50) P262C Nevee-Tilford silt Somewhat Nevee (50%) Depth to bedrock 160.8 6.8% loams, 3 to 10 limited (0.85) percent slopes Slow water movement (0.82) Tilford (30%) Slow water movement (0.87) Gypnevee, moist Depth to bedrock (5%) (0.91) Slow water movement (0.50) Nevee, very Slow water deep (5%) movement (0.82) Vale (5%) Slow water movement (0.82) P268E Nihill-Schamber Very limited Nihill, moist Slope (1.00) 31.6 1.3% gravelly (45%) loams, moist, Seepage, bottom 6 to 30 layer (1.00) percent slopes Schamber, moist Slope (1.00) (40%) Seepage, bottom layer (1.00) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 6 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) Nevee (5%) Slope (1.00) Depth to bedrock (0.85) Slow water movement (0.82) Spearfish (5%) Depth to bedrock (1.00) Slope (1.00) Nihill, Depth to bedrock moderately (1.00) deep (5%) Slope (1.00) Slow water movement (0.92) P324D Pierre-Fairburn- Very limited Pierre, moist Slow water 80.1 3.4% Ucross (30%) movement complex, (1.00) moist, 6 to 25 percent slopes Depth to bedrock (1.00) Slope (1.00) Fairburn, moist Depth to bedrock (25%) (1.00) Slope (1.00) Ucross, moist Depth to bedrock (25%) (1.00) Slope (1.00) Slow water movement (0.98) Maitland (5%) Slope (1.00) Slow water movement (0.98) Recluse, moist Slow water (5%) movement (1.00) Slope (0.16) Mittenbutte (5%) Depth to bedrock (1.00) Slope (1.00) P328E Pitchdraw- Very limited Pitchdraw (55%) Depth to bedrock 160.1 6.8% Mittenbutte (1.00) very fine sandy loams, Slope (1.00) moist, 6 to 40 percent slopes Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 7 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) Seepage, bottom layer (1.00) Mittenbutte, Depth to bedrock moist (30%) (1.00) Slope (1.00) Ucross (5%) Depth to bedrock (1.00) Slope (1.00) Slow water movement (0.98) Recluse, moist Slow water (5%) movement (1.00) Slope (0.16) Alice, moist (5%) Seepage, bottom layer (1.00) Slope (0.16) Slow water movement (0.08) P330E Pitchdraw- Very limited Pitchdraw (55%) Depth to bedrock 8.9 0.4% Mittenbutte (1.00) very fine sandy loams, Slope (1.00) moist, 6 to 40 Seepage, bottom percent layer (1.00) slopes, very stony Mittenbutte, Depth to bedrock moist, very (1.00) stony (30%) Slope (1.00) Recluse, moist Slow water (5%) movement (1.00) Slope (0.16) Alice, moist (5%) Seepage, bottom layer (1.00) Slope (0.16) Slow water movement (0.08) Ucross (5%) Depth to bedrock (1.00) Slope (1.00) Slow water movement (0.98) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 8 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) P334F Pits, gravel- Very limited Pits, gravel Slope (1.00) 15.0 0.6% Dumps (55%) complex Slow water movement (1.00) Large stones (0.92) P356A Recluse loam, Very limited Recluse, moist Slow water 222.3 9.4% moist, 0 to 2 (90%) movement percent slopes (1.00) Boneek, moist Slow water (5%) movement (1.00) Depth to bedrock (0.96) P356B Recluse loam, Very limited Recluse, moist Slow water 145.7 6.2% moist, 2 to 6 (90%) movement percent slopes (1.00) Boneek, moist Slow water (5%) movement (1.00) Depth to bedrock (0.96) P370D Recluse-Ziggy Very limited Recluse, moist Slow water 12.2 0.5% loams, moist, (41%) movement 6 to 15 (1.00) percent slopes Slope (0.16) Ucross (7%) Depth to bedrock (1.00) Slow water movement (0.98) Slope (0.63) Boneek, moist Slow water (6%) movement (1.00) Depth to bedrock (0.96) Slope (0.16) Fairburn, moist Depth to bedrock (3%) (1.00) Slope (0.63) P384D Rekop- Very limited Rekop, moist Depth to bedrock 19.7 0.8% Gypnevee- (40%) (1.00) Rock outcrop complex, Slope (0.04) moist, 3 to 15 Spearfish (5%) Depth to bedrock percent slopes (1.00) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 9 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) Slope (0.63) P448A Savo silty clay Very limited Savo, moist Slow water 6.2 0.3% loam, moist, 0 (85%) movement to 2 percent (1.00) slopes Altvan, moist Seepage, bottom (5%) layer (1.00) Slow water movement (0.08) Kyle (4%) Slow water movement (1.00) Slope (0.84) McKenzie (1%) Ponding (1.00) Depth to saturated zone (1.00) Slow water movement (1.00) P488A St. Onge loam, 0 Somewhat St. Onge, rarely Slow water 1.2 0.1% to 2 percent limited flooded (80%) movement slopes, rarely (0.92) flooded Flooding (0.40) Sodawells, rarely Flooding (0.40) flooded (4%) Recluse (4%) Slow water movement (0.47) Thirtynine, moist Slow water (4%) movement (0.82) Tilford (3%) Slow water movement (0.82) P508A Swint silt loam, 0 Somewhat Swint (85%) Slow water 40.7 1.7% to 2 percent limited movement slopes (0.92) Vale (4%) Slow water movement (0.82) Barnum, rarely Slow water flooded (4%) movement (0.50) Depth to saturated zone (0.43) Flooding (0.40) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 10 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) St. Onge, rarely Slow water flooded (3%) movement (0.92) Flooding (0.40) P514A Tilford silt loam, Somewhat Tilford (85%) Slow water 18.7 0.8% 0 to 2 percent limited movement slopes (0.82) St. Onge (5%) Slow water movement (0.82) Flooding (0.40) P514B Tilford silt loam, Somewhat Tilford (85%) Slow water 231.5 9.8% 2 to 6 percent limited movement slopes (0.82) Nevee (4%) Depth to bedrock (0.85) Slow water movement (0.82) St. Onge (4%) Slow water movement (0.82) Flooding (0.40) P514C Tilford silt loam, Somewhat Tilford (80%) Slow water 70.9 3.0% 6 to 10 limited movement percent slopes (0.82) Nevee (10%) Depth to bedrock (0.85) Slow water movement (0.82) Vale (5%) Slow water movement (0.82) Suglo (5%) Slow water movement (0.24) P536D Ustorthents, Somewhat Ustorthents, Slow water 6.0 0.3% reclaimed, 1 to limited reclaimed movement 20 percent (90%) (0.95) slopes Slope (0.16) Nihill, moist (4%) Slope (0.16) P538A Vale silt loam, 0 Somewhat Vale (85%) Slow water 257.2 10.9% to 2 percent limited movement slopes (0.82) Tilford (6%) Slow water movement (0.87) Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 11 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Map unit Map unit name Rating Component Rating reasons Acres in AOI Percent of AOI symbol name (percent) (numeric values) Nevee (3%) Depth to bedrock (0.85) Slow water movement (0.82) P538B Vale silt loam, 2 Somewhat Vale (85%) Slow water 223.3 9.5% to 6 percent limited movement slopes (0.82) Tilford (5%) Slow water movement (0.87) Nevee (3%) Depth to bedrock (0.85) Slow water movement (0.82) P538C Vale silt loam, 6 Somewhat Vale (85%) Slow water 3.2 0.1% to 9 percent limited movement slopes (0.82) Nevee (5%) Depth to bedrock (0.85) Slow water movement (0.82) Tilford (5%) Slow water movement (0.87) P540B Vale silt loam, Somewhat Vale, gravelly Slow water 12.5 0.5% gravelly limited substratum movement substratum, 1 (85%) (0.98) to 6 percent slopes Nevee (5%) Depth to bedrock (0.85) Slow water movement (0.82) W Water Not rated Water (100%) 1.3 0.1% Subtotals for Soil Survey Area 2,305.4 97.8% Totals for Area of Interest 2,358.1 100.0% Rating Acres in AOI Percent of AOI Somewhat limited 1,287.6 54.6% Very limited 1,069.2 45.3% Null or Not Rated 1.3 0.1% Totals for Area of Interest 2,358.1 100.0% Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 12 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Description Septic tank absorption fields are areas in which effluent from a septic tank is distributed into the soil through subsurface tiles or perforated pipe. Only that part of the soil between depths of 24 and 60 inches is evaluated. The ratings are based on the soil properties that affect absorption of the effluent, construction and maintenance of the system, and public health. Saturated hydraulic conductivity (Ksat), depth to a water table, ponding, depth to bedrock or a cemented pan, and flooding affect absorption of the effluent. Stones and boulders, ice, and bedrock or a cemented pan interfere with installation. Subsidence interferes with installation and maintenance. Excessive slope may cause lateral seepage and surfacing of the effluent in downslope areas. Some soils are underlain by loose sand and gravel or fractured bedrock at a depth of less than 4 feet below the distribution lines. In these soils the absorption field may not adequately filter the effluent, particularly when the system is new. As a result, the ground water may become contaminated. The ratings are both verbal and numerical. Rating class terms indicate the extent to which the soils are limited by all of the soil features that affect the specified use. "Not limited" indicates that the soil has features that are very favorable for the specified use. Good performance and very low maintenance can be expected. "Somewhat limited" indicates that the soil has features that are moderately favorable for the specified use. The limitations can be overcome or minimized by special planning, design, or installation. Fair performance and moderate maintenance can be expected. "Very limited" indicates that the soil has one or more features that are unfavorable for the specified use. The limitations generally cannot be overcome without major soil reclamation, special design, or expensive installation procedures. Poor performance and high maintenance can be expected. Numerical ratings indicate the severity of individual limitations. The ratings are shown as decimal fractions ranging from 0.01 to 1.00. They indicate gradations between the point at which a soil feature has the greatest negative impact on the use (1.00) and the point at which the soil feature is not a limitation (0.00). The map unit components listed for each map unit in the accompanying Summary by Map Unit table in Web Soil Survey or the Aggregation Report in Soil Data Viewer are determined by the aggregation method chosen. An aggregated rating class is shown for each map unit. The components listed for each map unit are only those that have the same rating class as listed for the map unit. The percent composition of each component in a particular map unit is presented to help the user better understand the percentage of each map unit that has the rating presented. Other components with different ratings may be present in each map unit. The ratings for all components, regardless of the map unit aggregated rating, can be viewed by generating the equivalent report from the Soil Reports tab in Web Soil Survey or from the Soil Data Mart site. Onsite investigation may be needed to validate these interpretations and to confirm the identity of the soil on a given site. Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 13 of 14 Septic Tank Absorption Fields—Butte County, South Dakota, and Lawrence County, South Dakota Rating Options Aggregation Method: Dominant Condition Aggregation is the process by which a set of component attribute values is reduced to a single value that represents the map unit as a whole. A map unit is typically composed of one or more "components". A component is either some type of soil or some nonsoil entity, e.g., rock outcrop. For the attribute being aggregated, the first step of the aggregation process is to derive one attribute value for each of a map unit's components. From this set of component attributes, the next step of the aggregation process derives a single value that represents the map unit as a whole. Once a single value for each map unit is derived, a thematic map for soil map units can be rendered. Aggregation must be done because, on any soil map, map units are delineated but components are not. For each of a map unit's components, a corresponding percent composition is recorded. A percent composition of 60 indicates that the corresponding component typically makes up approximately 60% of the map unit. Percent composition is a critical factor in some, but not all, aggregation methods. The aggregation method "Dominant Condition" first groups like attribute values for the components in a map unit. For each group, percent composition is set to the sum of the percent composition of all components participating in that group. These groups now represent "conditions" rather than components. The attribute value associated with the group with the highest cumulative percent composition is returned. If more than one group shares the highest cumulative percent composition, the corresponding "tie-break" rule determines which value should be returned. The "tie-break" rule indicates whether the lower or higher group value should be returned in the case of a percent composition tie. The result returned by this aggregation method represents the dominant condition throughout the map unit only when no tie has occurred. Component Percent Cutoff: None Specified Components whose percent composition is below the cutoff value will not be considered. If no cutoff value is specified, all components in the database will be considered. The data for some contrasting soils of minor extent may not be in the database, and therefore are not considered. Tie-break Rule: Higher The tie-break rule indicates which value should be selected from a set of multiple candidate values, or which value should be selected in the event of a percent composition tie. Natural Resources Web Soil Survey 8/22/2022 Conservation Service National Cooperative Soil Survey Page 14 of 14