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HomeMy WebLinkAboutPALMOS INDUSTRIAL - PDP220012 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT Drainage Report for Fort Collins Palmos Industrial 115 Hickory Street Fort Collins, CO 80524 Prepared by: Nicholas Andersen Reviewed by: Mike Beach, P.E. Project #:22-195-001 Dated: June 10, 2022 541 East Garden Drive, Unit N, Windsor, CO 80550 (970) 663-4552 EMAIL: mbeach@ridgetopeng.com 2 | Page Section Page 1. Project Engineer’s Certification ........................................................................................ 3 2. Project Location & Overview ............................................................................................ 4 3. Drainage Design Criteria ................................................................................................... 5 4. Hydraulic Calculations ....................................................................................................... 6 5. Facility Design .................................................................................................................... 7 6. Conclusion ......................................................................................................................... 8 7. References ......................................................................................................................... 8 Appendix A – Site Vicinity Map Appendix B – Flood Insurance Rate Map Appendix C – NRCS Soils Map Appendix D – Hydrologic Criteria Fort Collins Rainfall Intensity Curve Fort Collins Rainfall Intensity Table Table RO-3 – Recommended Percentage Imperviousness Values Appendix E – Hydraulic Calculations Runoff Coefficients & Imperviousness Time of Concentration - SF-2 Rational Method Runoff Flows – SF-3 (2-Year Event) Rational Method Runoff Flows – SF-3 (10-Year Event) Rational Method Runoff Flows – SF-3 (100-Year Event) Rain Garden Calculations LID Summary Drain Times Appendix F – Maps Drainage Plan/Subbasin Map Appendix G – References Table of Contents 3 | Page Section 1: PROJECT ENGINEER’S CERTIFICATION I hereby attest that this Final Drainage Report for the design of stormwater management facilities for Palmos Industrial on 115 Hickory St. was prepared by me, or under my direct supervision, in accordance with the provisions of the City of Fort Collins Storm Drainage Design Criteria and Construction Standards for the responsible parties thereof. __________________________ Mike Beach, P.E. Registered Professional Engineer State of Colorado No. 45088 4 | Page Section 2: Project Location & Overview Location The sites address is 115 Hickory St, Fort Collins, CO. For Recording purposes: Part of the Southeast Quarter of Section 2, Township 7 N, R 69 W of the 6th PM. Located along the south side of Hickory St., the site is described as above and contains 3.04 acres of undeveloped land. (See Appendix A – Site Vicinity Map) This site is located in the Dry Creek Basin, which generally flows west to east. A master plan update is currently underway to improve drainage in the area and prevent flooding. Existing Condition The existing site is covered by an existing vegetation and gravel that mainly flows runoff to the north and east. Stormwater runoff collects into curb and gutter along the north and into existing stormwater infrastructure within the road. Proposed Condition The intent of the development is to construct several new buildings totaling approximately 33,586 SF, concrete parking, curb and gutter, detention ponds, and landscaping. The city requires that all new or modified impervious areas have standard water quality treatment and Low impact development (LID) to treat runoff. Permeable pavers are to be installed within the parking area. The parking areas will then release to either of the new detention ponds. Floodplain FEMA Floodplain mapping in this neighborhood is located on map-panel 08069C0977G, Effective June 17, 2008, however it appears the subject property is located in Zone X, which is outside the 100-year floodplain. Existing Soils The Natural Resource Conservation Service mapped the historic soils on the site as Nunn Clay Loam. The Hydrologic Class is Type ‘C’ Soils. (Appendix C – NRCS Soils Map) 5 | Page Section 3: Drainage Design Criteria Reference Manuals Storm drainage design criteria is defined in the City of Fort Collins “Storm Water Criteria Manual (FCSWCM) and Amendments, which references to the “Urban Drainage and Flood Control District” (UDFCD) and the “Urban Storm Drainage Criteria Manual” (USDCM), Volumes 1, 2, and 3, dated 2008 with revisions (the Manual), are used and referenced in this report. Low Impact Development (LID) Requirements The proposed development is required to meet the City’s current Land Use Code, which includes: - 50% of the newly added or modified impervious area must be treated by LID techniques and 25% of new paved areas must be pervious. - 75% of all newly added or modified impervious area must be treated by LID techniques. Four Step Process The City of Fort Collins has adopted the “Four Step Process” that is recommended in Volume 3 of the USDCM for selecting BMP’s in urban redevelopment areas. The goal of this process is to minimize adverse impacts on receiving waters. The following describe how each step of the process are incorporated in the proposed development: Step 1 – Employ Runoff Reduction Practices The impacts of the proposed development will be less due to the addition of LID practices. The project proposes to install permeable pavements with underdrains to aid in conveyance and infiltration opportunities which will reduce the effects of the added impervious area from the development of the site. Step 2 – Water Quality Capture Volume (WQCV) In order to reduce the sediment load and other pollutants leaving the site, it is important to provide WQCV to minimize the downstream impacts. This project proposes to provide permeable pavements with storage capacity for the WQCV. The runoff from the permeable pavements will then flow to the detention pond to be released at the required rate. Step 3 – Stabilize Drainageways Since this site is in close proximity to Poudre River it is important to take this step into consideration. By providing stormwater detention and water quality and lowering the historic runoff and providing a metered outflow, the project impacts to the drainageway are essentially reduced. The majority of the drainageway leaving the site is already stabilized. 6 | Page Step 4 – Implement Site Specific and Other Source Control BMP’s The proposed project will contain the following BMP’s: Permeable Pavement: Most runoff from the project site will be directed into and through the proposed BMP facilities prior to leaving the site. Permeable pavements allow vehicle travel while allowing water to enter the soils and have additional storage of storm runoff. Maintenance: In order for BMP’s to remain effective proper maintenance needs are required. Scheduled visual inspections and routine repair after larger storm events are critical in the maintenance and effectiveness of the installed BMP’s. The sites owner will be advised of these practices during installation in order to maximize the efficiency of the installed BMP’s. Section 4: Hydraulic Calculations Criteria Runoff criteria for the proposed sites was analyzed for the 2-YR, 10-YR, and 100-YR storm events. The Rational Method is being used for the design of the proposed improvements. Rainfall Intensities used in the proposed design were determined as a function of the Time of Concertation for each subbasin. The values used were determined by the City of Fort Collins Rainfall Intensity/Duration/Frequency curve (Figure 3.4-1 and Table 3.4-1 (see Appendix D). Imperviousness Values from Table 4.1-3 (Fort Collins Amendment to the USDCM) were used in determining the sites imperviousness. The overall proposed site improvements and landscaping equate to a total disturbed Imperviousness of 60.8%. Time of Concentration & Runoff Coefficient The onsite area was separated into three (10) subbasins with slopes varying between 0.5% to 3.0%. The calculated Time of Concentration (TC) for each subbasin are listed in Appendix E. See Basin Map in Appendix F for more information. WQCV The UD-BMP_v3.07 (UDFCD) spreadsheet was used to calculate the required permeable pavement area and volume. See Appendix E for design information. Open Grated Nyloplast structures (or equivalent) tied to the detention pond will be installed within the pavements to drain the soils over 12 hours. Detention The UD-detention_v2.35 (UDFCD) spreadsheet was used to calculate the required storage volumes of the two detention ponds. See appendix E for design information. 7 | Page Section 5: Facility Design The proposed improvements will increase imperviousness from the undeveloped condition, so measures have been included in the design to minimize the amount of stormwater released from the site. The site was broken into 10 developed subbasins for analyzation; See Appendix E for breakdown of the different area types for each subbasin and Appendix F for the Subbasin Map. Subbasin 1 - contains undeveloped land to the southwest of Building 1. This basin will continue to flow to the southwest as it has in the existing condition. Subbasin 2 - contains Buildings 1, 2, and 3, parking west of Mason, and Detention Pond 1. This basin’s impervious areas will largely be directed over the permeable pavers and into the detention pond. Subbasin 3 - contains landscaped area to the west of Building 2. This basin will flow to a nyloplast and drain directly to the detention pond. Subbasin 4 - contains landscaped area to the north of Building 2. This basin will flow to a nyloplast and drain directly to the detention pond. Subbasin 5 - contains additional right of way for the detached walk and tree lawn, landscape to the north of Buildings 1, 3, and 4, and a portion of Mason St. This basin will flow into curb and gutter in the right of way and into existing storm infrastructure to the east. Subbasin 6 - contains the west portion of Mason St. This basin flows to a Type R, which will then convey the flows to a sump pump and into the existing storm infrastructure. Subbasin 7 - contains the east portion of Mason St. This basin flows to a Type R, which will then convey the flows to a sump pump and into the existing storm infrastructure. Subbasin 8 - contains Building 4, parking, and Detention Pond 2. This basin will flow to the south along permeable pavers and into the detention pond. Subbasin 9 - contains undeveloped land to the east of Building 4. This basin will continue to flow to the east as it has in the existing condition. Subbasin 10 - contains undeveloped land to the south of Detention Pond 2. This basin will continue to flow to the south as it has in the existing condition. See table 1 below for basin breakdown. 8 | Page Basin Area (ac) Imperviousness (%) 2-yr Runoff (cfs) 10-yr Runoff (cfs) 100-yr Runoff (cfs) 1 0.12 2.0 0.00 0.07 0.47 2 1.87 69.6 1.94 3.84 9.38 3 0.04 8.5 0.00 0.03 0.17 4 0.06 17.1 0.02 0.06 0.27 5 0.28 51.5 0.30 0.67 1.86 6 0.14 70.1 0.21 0.42 1.02 7 0.11 78.4 0.20 0.38 0.87 8 0.32 63.2 0.42 0.86 2.19 9 0.06 2.0 0.00 0.03 0.24 10 0.03 2.0 0.00 0.02 0.13 Total 3.04 60.8 3.10 6.38 16.60 The detention ponds were designed using spreadsheet UD-Detention_v2.35 from UDFCD. Per Fort Collins requirements the ponds were designed to release the 100-yr developed runoff at the 2-yr historic rate. See table 2 below for detention pond summaries. Pond 1 Pond 2 Bottom of Pond (ft) 4972.04 4971.84 Top of Pond (ft) 4976.12 4975.88 Pond Capacity (ac-ft) 0.518 0.163 100-yr Vol. (ac-ft) 0.459 0.73 100-yr Release Rate (cfs) 0.08 0.01 2-yr Pre-Developed Release Rate (cfs) 0.08 0.01 The permeable pavements were designed using UD-BMP_v3.07 from UDFCD. The areas were designed with 6” of pavement, 6” min. depth of reservoir, and 4” pipes. The area tributary to Detention Pond 1 is split into 4 cells, each approximately 200’x20’. These will flow to two Nyloplasts in the center and into the detention pond. The pipe ends will need an orifice of 0.5” diameter to release the WQCV over 12 hours (UD BMP calcs show 1-1/16” for the whole area, (4) 1/2” diameter orifices is the same area). Each pipe will have a cleanout at the other end. The area tributary to Detention Pond 2 is approximately 100’x30’. This cell will flow to a Nyloplast on the east side and into the detention pond. The pipe outlet will need an orifice of 3/8” diameter to release the WQCV over 12 hours. Each pipe will have a cleanout at the other end. 9 | Page Section 6: Conclusions All computations that have been reviewed or completed within this report are in compliance with the City of Fort Collins Storm Drainage Design Criteria and Construction Standards manual and the Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual Volumes 1, 2, & 3. The proposed drainage concepts presented in this report and on the construction plans adequately provides for water quality treatment of impervious areas by collecting storm events within the proposed rain garden. Section 7: References • The Natural Resource Conservation Service Soil Survey for Larimer County and the WSS website. • FEMA FIRM map-panel 08069C0977G Effective 6/17/2008. • “City of Fort Collins Stormwater Criteria Manual” dated December 2018 • Urban Drainage and Flood Control District Urban Storm Drainage Criteria Manual (UDFCD), Volumes 1, 2, and 3, dated 2008 with revisions (the Manual). w Appendix A Site Vicinity Map Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e Label contains b r o ke n r e f er e n c e HICKORY STCONIFER STEL SUNIGA RDE VINE DRW VINE DRN SHIELDS STBLUE SPRUCE DRHIGHWAY 287HEMLOCK STREDWOOD STN MASON ST Appendix B Flood Insurance Rate Map Appendix C NRCS Soils Map United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Larimer County Area, Colorado Palmos Industrial Natural Resources Conservation Service October 7, 2022 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/ portal/nrcs/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/? cid=nrcs142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require 2 alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. 3 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................11 Map Unit Descriptions.........................................................................................11 Larimer County Area, Colorado......................................................................13 73—Nunn clay loam, 0 to 1 percent slopes.................................................13 References............................................................................................................15 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil-vegetation-landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil-landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field-observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and Custom Soil Resource Report 6 identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. Custom Soil Resource Report 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 4494600449463044946604494690449472044947504494780449481044946004494630449466044946904494720449475044947804494810493120 493150 493180 493210 493240 493270 493300 493330 493360 493390 493420 493450 493120 493150 493180 493210 493240 493270 493300 493330 493360 493390 493420 493450 40° 36' 14'' N 105° 4' 53'' W40° 36' 14'' N105° 4' 38'' W40° 36' 7'' N 105° 4' 53'' W40° 36' 7'' N 105° 4' 38'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,560 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Larimer County Area, Colorado Survey Area Data: Version 17, Sep 7, 2022 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 2, 2021—Aug 25, 2021 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 73 Nunn clay loam, 0 to 1 percent slopes 4.1 100.0% Totals for Area of Interest 4.1 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. Custom Soil Resource Report 11 An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 12 Larimer County Area, Colorado 73—Nunn clay loam, 0 to 1 percent slopes Map Unit Setting National map unit symbol: 2tlng Elevation: 4,100 to 5,700 feet Mean annual precipitation: 14 to 15 inches Mean annual air temperature: 48 to 52 degrees F Frost-free period: 135 to 152 days Farmland classification: Prime farmland if irrigated Map Unit Composition Nunn and similar soils:85 percent Minor components:15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Nunn Setting Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Parent material:Pleistocene aged alluvium and/or eolian deposits Typical profile Ap - 0 to 6 inches: clay loam Bt1 - 6 to 10 inches: clay loam Bt2 - 10 to 26 inches: clay loam Btk - 26 to 31 inches: clay loam Bk1 - 31 to 47 inches: loam Bk2 - 47 to 80 inches: loam Properties and qualities Slope:0 to 1 percent Depth to restrictive feature:More than 80 inches Drainage class:Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat):Moderately low to moderately high (0.06 to 0.20 in/hr) Depth to water table:More than 80 inches Frequency of flooding:None Frequency of ponding:None Calcium carbonate, maximum content:7 percent Maximum salinity:Nonsaline (0.1 to 1.0 mmhos/cm) Sodium adsorption ratio, maximum:0.5 Available water supply, 0 to 60 inches: High (about 9.1 inches) Interpretive groups Land capability classification (irrigated): 3e Land capability classification (nonirrigated): 4e Hydrologic Soil Group: C Ecological site: R067BY042CO - Clayey Plains Hydric soil rating: No Custom Soil Resource Report 13 Minor Components Heldt Percent of map unit:10 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY042CO - Clayey Plains Hydric soil rating: No Wages Percent of map unit:5 percent Landform:Terraces Landform position (three-dimensional):Tread Down-slope shape:Linear Across-slope shape:Linear Ecological site:R067BY002CO - Loamy Plains Hydric soil rating: No Custom Soil Resource Report 14 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/national/soils/?cid=nrcs142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http:// www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ home/?cid=nrcs142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 15 United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/ nrcs/detail/soils/scientists/?cid=nrcs142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/? cid=nrcs142p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf Custom Soil Resource Report 16 Appendix D Hydrologic Criteria FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 8 Table 3.4-1. IDF Table for Rational Method Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) Duration (min) Intensity 2-year (in/hr) Intensity 10-year (in/hr) Intensity 100-year (in/hr) 5 2.85 4.87 9.95 39 1.09 1.86 3.8 6 2.67 4.56 9.31 40 1.07 1.83 3.74 7 2.52 4.31 8.80 41 1.05 1.80 3.68 8 2.40 4.10 8.38 42 1.04 1.77 3.62 9 2.30 3.93 8.03 43 1.02 1.74 3.56 10 2.21 3.78 7.72 44 1.01 1.72 3.51 11 2.13 3.63 7.42 45 0.99 1.69 3.46 12 2.05 3.50 7.16 46 0.98 1.67 3.41 13 1.98 3.39 6.92 47 0.96 1.64 3.36 14 1.92 3.29 6.71 48 0.95 1.62 3.31 15 1.87 3.19 6.52 49 0.94 1.6 3.27 16 1.81 3.08 6.30 50 0.92 1.58 3.23 17 1.75 2.99 6.10 51 0.91 1.56 3.18 18 1.70 2.90 5.92 52 0.9 1.54 3.14 19 1.65 2.82 5.75 53 0.89 1.52 3.10 20 1.61 2.74 5.60 54 0.88 1.50 3.07 21 1.56 2.67 5.46 55 0.87 1.48 3.03 22 1.53 2.61 5.32 56 0.86 1.47 2.99 23 1.49 2.55 5.20 57 0.85 1.45 2.96 24 1.46 2.49 5.09 58 0.84 1.43 2.92 25 1.43 2.44 4.98 59 0.83 1.42 2.89 26 1.4 2.39 4.87 60 0.82 1.4 2.86 27 1.37 2.34 4.78 65 0.78 1.32 2.71 28 1.34 2.29 4.69 70 0.73 1.25 2.59 29 1.32 2.25 4.60 75 0.70 1.19 2.48 30 1.30 2.21 4.52 80 0.66 1.14 2.38 31 1.27 2.16 4.42 85 0.64 1.09 2.29 32 1.24 2.12 4.33 90 0.61 1.05 2.21 33 1.22 2.08 4.24 95 0.58 1.01 2.13 34 1.19 2.04 4.16 100 0.56 0.97 2.06 35 1.17 2.00 4.08 105 0.54 0.94 2.00 36 1.15 1.96 4.01 110 0.52 0.91 1.94 37 1.16 1.93 3.93 115 0.51 0.88 1.88 38 1.11 1.89 3.87 120 0.49 0.86 1.84 FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 3.0 Rational Method 3.4 Intensity-Duration-Frequency Curves for Rational Method Page 9 Figure 3.4-1. Rainfall IDF Curve – Fort Collins FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 4.0 SWMM 4.1 Input Parameters Page 10 4.0 SWMM This section is for project sites that require the use of the Stormwater Management Model (SWMM) to determine storm hydrograph routing and is the only method that is able to assess the overall performance of multiple detention basins in parallel or in series in a particular project site or watershed. Reference: The theory and methodology for reservoir routing is not covered in this Manual as this subject is well described in many hydrology reference books. The EPA SWMM Reference Manuals, dated January 2016, have been utilized in preparing the information in this section of the Manual. 4.1 Input Parameters Table 4.1-1 provides required input values to be used for SWMM modeling. Basin and conveyance element parameters must be computed based on the physical characteristics of the site. Table 4.1-1. SWMM Input Parameters Depth of Storage Impervious Areas 0.1 inches Pervious Areas 0.3 inches Infiltration Parameters Maximum 0.51 in/hr Minimum 0.50 in/hr Decay Rate 0.0018 in/sec or 6.48 in/hr Zero Detention Depth 1% Manning's "n" Pervious Surfaces 0.250 Impervious Surfaces 0.016 For Overall Drainage Plan (ODP) and Project Development Plan (PDP) submittals, when surface types may not yet be known, land uses may be used to estimate impervious percentages. Table 4.1-2 lists the percent imperviousness for common types of land uses in the City. FORT COLLINS STORMWATER CRITERIA MANUAL Hydrology Standards (Ch. 5) 4.0 SWMM 4.1 Input Parameters Page 11 Table 4.1-2. Land Use - Percent Impervious Land Use Percent Impervious (%) Residential Urban Estate 30 Low Density 50 Medium Density 70 High Density 90 Commercial Commercial 80 Industrial 90 Undeveloped Open Lands, Transition 20 Greenbelts, Agriculture 2 Offsite Flow Analysis (when Land Use not defined) 45 Reference: For further guidance regarding zoning classifications, refer to the Land Use Code, Article 4. For Final Plan (FP) submittals, impervious values must be based on the proposed land surface types. Refer to Table 4.1-3 for recommended percent impervious values. Table 4.1-3. Surface Type – Percent Impervious Surface Type Percent Impervious (%) Hardscape or Hard Surface Asphalt, Concrete 100 Rooftop 90 Recycled Asphalt 80 Gravel 40 Pavers 40 Landscape or Pervious Surface Playgrounds 25 Lawns, Sandy soil 2 Lawns, Clayey soil 2 Appendix E Hydraulic Calculations Designer: Company:2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr Date:1-hour rainfall depth, P1 (in) =0.82 1.40 2.86 Project:a b c Location:Rainfall Intensity Equation Coefficients =28.50 10.00 0.786 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr Overland Flow Length Li (ft) U/S Elevation (ft) (Optional) D/S Elevation (ft) (Optional) Overland Flow Slope Si (ft/ft) Overland Flow Time ti (min) Channelized Flow Length Lt (ft) U/S Elevation (ft) (Optional) D/S Elevation (ft) (Optional) Channelized Flow Slope St (ft/ft) NRCS Conveyance Factor K Channelized Flow Velocity Vt (ft/sec) Channelized Flow Time tt (min) Computed tc (min) Regional tc (min) Selected tc (min)2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr 500-yr 0.01 0.05 0.15 0.33 0.40 0.49 0.59 6.74 7.21 10.00 2.22 3.79 7.74 0.00 0.07 0.47 0.56 0.60 0.64 0.71 0.74 0.77 0.81 10.11 14.83 14.83 1.87 3.20 6.53 1.94 3.84 9.38 0.05 0.10 0.19 0.37 0.43 0.52 0.61 6.40 7.10 10.00 2.22 3.79 7.74 0.00 0.03 0.17 0.11 0.17 0.26 0.41 0.48 0.55 0.64 5.95 8.30 10.00 2.22 3.79 7.74 0.02 0.06 0.27 0.40 0.45 0.51 0.61 0.65 0.69 0.75 4.63 4.97 5.00 2.78 4.75 9.70 0.30 0.67 1.86 0.56 0.61 0.65 0.71 0.74 0.77 0.81 3.55 4.49 5.00 2.78 4.75 9.70 0.21 0.42 1.02 0.63 0.67 0.71 0.76 0.78 0.80 0.83 3.06 4.00 5.00 2.78 4.75 9.70 0.20 0.38 0.87 0.50 0.55 0.60 0.67 0.71 0.74 0.79 5.59 6.17 6.17 2.62 4.48 9.14 0.42 0.86 2.19 0.01 0.05 0.15 0.33 0.40 0.49 0.59 3.52 3.59 10.00 2.22 3.79 7.74 0.00 0.03 0.24 0.01 0.05 0.15 0.33 0.40 0.49 0.59 5.99 6.15 10.00 2.22 3.79 7.74 0.00 0.02 0.13 C 69.6 0.02020.00 Rainfall Intensity, I (in/hr) 1.41 0.47 26.17100.02040.00 Peak Flow, Q (cfs) Calculation of Peak Runoff using Rational Method Overland (Initial) Flow Time Channelized (Travel) Flow Time Time of ConcentrationRunoff Coefficient, C Subcatchment Name Area (ac) NRCS Hydrologic Soil Group Percent Imperviousnes s 1 0.12 C 2.0 Select UDFCD location for NOAA Atlas 14 Rainfall Depths from the pulldown list OR enter your own depths obtained from the NOAA website (click this link) Cells of this color are for required user-input Cells of this color are for optional override values Cells of this color are for calculated results based on overrides NGA Ridgetop Engineering and Surveying 10/7/2022 Palmos Fort Collins Version 2.00 released May 2017 20 1.41 2.36 19.20 3 0.04 C 8.5 20.00 0.020 60.00 0.005 20 1.41 0.71 0.005 20 1.41 4.71200.00 0.020 400.0021.87 17.66 27.23 5 0.28 C 51.5 25.00 0.020 40.00 0.010 20 2.00 0.33 25.94 4 0.06 C 17.1 20.00 0.020 200.00 0.005 15.09 7 0.11 C 78.4 25.00 0.020 80.00 0.005 20 1.41 0.94 0.005 20 1.41 0.940.020 80.0060.14 C 70.1 25.00 15.92 9 0.06 C 2.0 10.00 0.050 10.00 0.050 10 2.24 0.07 13.62 8 0.32 C 63.2 50.00 0.020 50.00 0.005 20 1.41 0.59 25.84 25.74 10 0.04 C 2.0 10.00 0.010 10.00 0.010 10 1.00 0.17 I 𝑖𝑖𝑖𝑖/ℎ𝑟𝑟=a ∗P1b+tc c ti =0.395 1.1 −C5 LiSi0.33tt=Lt60K St =Lt60Vt Computed tc =ti +tt Regional tc =26 −17i +Lt6014i+9 St Selected tc =max tminimum ,min Computed tc ,Regional tc tminimum =5 (urban) tminimum =10 (non-urban) Q 𝑐𝑐𝑐𝑐𝑐𝑐=CIA Weighted Runoff Coefficients Calculated By: JKS Project :Palmos Industrial Checked By: MRB Job Number: -Date:10/7/2022 Proposed/IMP%Soil Types: Nunn Clay Loam, 0-1 % Existing Roof 90 Concrete Drive/Walk 90 Landscaping 2 Hydrologic Grouping:Type C/D Gravel 40 Multi-family (attached)75 Runoff Coefficients:C = Kc Commercial 50 Kc(2year) = 0.83i^1.122 Undeveloped Historical 2 Kc(5year) = 0.82i+0.035 Kc(10year) = 0.74i+0.132 Kc(100year) = 0.41i+0.484 Proposed Basins (proposed conditions)Land Use (Acres)Weighted Runoff Coefficient Total Concrete Basin Area Roof Drive/Walk Landscape Gravel Residential Pavers C2 C5 C10 C100 %Imp 1 0.12 0.00 0.00 0.12 0.00 0.00 0.00 0.01 0.05 0.11 0.49 2.0 2 1.87 0.67 0.77 0.43 0.00 0.00 0.00 0.55 0.60 0.61 0.77 69.6 3 0.04 0.00 0.00 0.04 0.00 0.00 0.00 0.05 0.10 0.16 0.52 8.5 4 0.06 0.00 0.01 0.05 0.00 0.00 0.00 0.11 0.17 0.22 0.55 17.1 5 0.28 0.00 0.16 0.12 0.00 0.00 0.00 0.39 0.45 0.48 0.70 51.5 6 0.14 0.00 0.11 0.03 0.00 0.00 0.00 0.56 0.60 0.62 0.77 70.1 7 0.11 0.00 0.10 0.01 0.00 0.00 0.00 0.63 0.67 0.68 0.81 78.4 8 0.32 0.10 0.12 0.10 0.00 0.00 0.00 0.50 0.55 0.57 0.74 63.2 9 0.06 0.00 0.00 0.06 0.00 0.00 0.00 0.01 0.05 0.11 0.49 2.0 10 0.03 0.00 0.00 0.03 0.00 0.00 0.00 0.01 0.05 0.11 0.49 2.0 Pond 1 1.98 0.67 0.78 0.53 0.00 0.00 0.00 0.53 0.57 0.59 0.76 66.6 Pond 2 0.32 0.10 0.12 0.10 0.00 0.00 0.00 0.50 0.55 0.57 0.74 63.2 Total 3.04 0.77 1.26 1.01 0.00 0.00 0.00 0.47 0.53 0.55 0.73 60.8 15 | Page Appendix F Maps CP TRACKSCP RAILGATECHAIN LINK FENCECHAIN LINK FENCECHAIN LINK FENCECHAIN LINK FENCEGATEGATEREAL ESTATEFOR SALE 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