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HomeMy WebLinkAboutDrainage Reports - 07/09/2002PROPERTY OF M rrJved Report JUN 5 2002 !'OBIT COLLINB ate =` Z FINAL DRAINAGE AND ZOSION CONTROL REPORT Swallow 8-Plex ek 3, Thunderbird Estates Ninth Filing J•R ENGINEERING A Subsidiary of Westrian FINAL DRAINAGE AND EROSION CONTROL REPORT Swallow 8-Plex Lot 2, Block 3, Thunderbird Estates Ninth Filing Prepared for: Lagunitas Companies 3950 JFK Parkway Building 12B Fort Collins, Colorado 80525 (970) 226-5000 Prepared by: JR Engineering 2620 E. Prospect Road, Suite 190 Fort Collins, Colorado 80525 (970)491-9888 June 4, 2002 Job Number 9116.06 June 4, 2002 Mr. Basil Hamdan City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, CO 80521 J•R ENGINEERING A Subsidiary of Westrian RE: Final Drainage and Erosion Control Report for Swallow 8-Plex - Revised Dear Basil, We are pleased to submit to you for your approval, this revised Final Drainage and Erosion Control Report for Swallow 8-Plex, a redevelopment of an existing car wash site. The site is located in Fort Collins, Colorado at the southwest corner of the intersection of Swallow Road and Remington Street. This report includes revisions based on Stormwater's review comments dated December 12, 2001. All computations within this report have been completed in compliance with the City of Fort Collins Storm Drainage Design Criteria. We greatly appreciate your time and consideration in reviewing this submittal. Please call if you have any questions. Sincerely, 0�i Aj Amber Reed Robert Almirall, PE Engineer H Director of Operations O�PpO REr'�`S'T Attachments ��; OOPS 0 ;O ¢ 33441 F' A J. O •', tV ��SS�aIVRI E���2 2620 Fast Prospect Road, Suite 190, Fort Collins, CO 80525 970-491-9888 • Fax: 970A91-9984 • w jrengineeringxom TABLE OF CONTENTS PAGE ' TABLE OF CONTENTS................................................................................................................ ii 1. INTRODUCTION 1.1 ..................................................................................................................I Project Description..........................................................................................................1 1.2 Existing Site Characteristics...........................................................................................1 1.3 1.4 Purpose and Scope of Report ..........................................................................................I Design Criteria................................................................................................................1 1.5 Master Drainage Basin....................................................................................................2 ' 2. HISTORIC (EXISTING) DRAINAGE................................................................................2 3. LOCAL DEVELOPED DRAINAGE DESIGN...................................................................2 3.1 Method.............................................................................................................................2 3.2 General Flow Routing.....................................................................................................3 4. WATER QUALITY ............................ :................................................................................... 4 5. EROSION CONTROL...........................................................................................................5 5.1 Erosion and Sediment Control Measures........................................................................5 5.2 Dust Abatement........................................................................:......................................5 5.3 Tracking Mud on City Streets.........................................................................................5 5.4 Maintenance....................................................................................................................6 5.5 Permanent Stabilization..................................................................................................6 5. REFERENCES.......................................................................................................................7 APPENDIX A MAPS AND FIGURES APPENDIX B HYDROLOGIC CALCULATIONS APPENDIX C HYDRAULIC CALCULATIONS APPENDIX D WATER QUALITY APPENDIX E EROSION CONTROL H 1 1. INTRODUCTION 1.1 Project Description Swallow 8-Plex is a proposed redevelopment located on Lot 2, Block 3, Thunderbird Estates Ninth Subdivison. The site is located in the Foothills Drainage Basin and contains approximately 0.27 Acres. The site is zoned C, Commercial. The proposed site is located at the southwest corner of Swallow Road and Remington Street. The project is a portion of Section 25, Township 7 North, Range 69 West of the Sixth Principal Meridian, in the City of Fort Collins, Larimer County, Colorado. A vicinity map is provided in Appendix A. ' 1.2 Existing Site Characteristics According to the "Soil Survey for Larimer County Area, Colorado" (USDA) soils include: Altvan-Santana loam (3) & Nunn clay loam (74). These soils have slow to moderate runoff and slight to moderate erosion. The site is within the moderate wind erodibility zone according to the Wind Erodibility Map for the City of Fort Collins. The soils map is provided in Appendix A. 1.3 Purpose and Scope of Report ' This report defines the proposed drainage and erosion control plan for Swallow 8-Plex. The plan includes consideration of all on -site and tributary off -site runoff and the design of all drainage facilities required for this development. This drainage plan maintains existing drainage patterns. ' 1.4 Design Criteria This report was prepared to meet or exceed the submittal requirements established in the City of Fort Collins' "Storm Drainage Design Criteria and Construction Standards" (SDDCCS), dated May 1984. Where applicable, the criteria established in the "Urban Storm Drainage Criteria Manual" (UDFCD) dated 1984, developed by the Denver Regional Council of Governments have been utilized. t Final Drainage and Erosion Control Report Page 1 Swallow 8-Plex June 4, 2002 I 1 I I r� 1.5 Master Drainage Basin Swallow 8-Plex lies in the Foothills Drainage Basin. The site lies in Basin 25 as defined by the Final Report for Hydrologic Model Update for the Foothills Basin Master Drainage Plan (Anderson, 1999). Basin 25 is a commercial basin with 90 % imperviousness and a 1.5% slope that drains to the Foothills Regional Channel east of Stanford Road. 2. HISTORIC (EXISTING) DRAINAGE The historic (existing) flows for Lot 2, Block 3, Thunderbird Estates Ninth Subdivision are split north and south. A small portion of the lot drains north to Swallow Road, with the remainder draining south to a concrete pan which runs through Southmoor Village 5 h Filing (Ross Department Store). Both flow paths join downstream at the Foothills Regional Channel, east of Stanford Road. The site has an average slope of 2.6 percent. The majority of the site is paved with a small amount of landscaping. An existing 2' trickle pan conveys flows toward the south lot line. This trickle pan ends short of the Ross Department Store Parking Lot and currently cascade over bare soil. A small portion of the back of Lot 1, Block 3, Thunderbird Estates Ninth Subdivision (Diamond Shamrock Filling Station) drains to the west property line of the site. This offsite flow (Offsite Basin 01) appears to pond near the middle of the lot line until it spills to the south. According to the Flood Insurance Rate Map (FIRM) for the area, the site lies out of the 100- YR Floodplain. The site is shown on a portion of the FIRM Map Panel No. 0801020012C in Appendix.A. 3. LOCAL DEVELOPED DRAINAGE DESIGN 3.1 Method Since the subbasins are less than 160 acres, the Rational Method was used to determine both the 10-year and 100-year runoff rates for the sub -basins indicated in this drainage report. Final Drainage and Erosion Control Report Page 2 Swallow 8-Plex June 4, 2002 Drainage facilities were designed to convey the 100-year peak flows. The Runoffcoefficients were assigned using Table 3-2 of the SDDCCS Manual. The Rational Method is given by: Q = CtCIA (1) where Q is the maximum rate of runoff in cfs, A is the total area of the basin in acres, Cf is the storm frequency adjustment factor, C is the runoff coefficient, and I is the rainfall intensity in inches per hour for a storm duration equal to the time of concentration. The frequency adjustment factor, Cf, is 1.0 for the initial 10-year storm and 1.25 for the major 100-year storm. The runoff coefficient is dependent on land use or surface characteristics. The rainfall intensity is selected from Rainfall Intensity Duration Curves for the City of Fort Collins (Figure 3.1 of SDDCCS). In order to utilize the Rainfall Intensity Duration Curves, the time of concentration is required. The following equation is used to determine the time of concentration to=ti+tt (2) where t, is the time of concentration in minutes, ti is the initial or overland flow time in minutes, and tt is the conveyance travel time in minutes. The initial or overland flow time is calculated with the SDDCCS Manual equation: t; = [1.87(1.1 - CCf)LO.sl/(S)0.33 (3) where L is the length of overland flow in feet (limited to a maximum of 500 feet), S is the average slope of the basin in percent, and C and Cf are as defined previously. 3.2 General Flow Routing Flows within this site will take the form of overlot and gutter flow. The existing drainage patterns have been maintained as much as possible. All calculations can be found in Appendix B. Stormwater detention is not required for Swallow 8-Plex because impervious values are not increased. Flows to the north (Subbasin 101) will travel overland to Swallow Road. Flows Final Drainage and Erosion Control Report Page 3 Swallow 8-Plex June 4, 2002 I IJ 1 1 I to the south (Subbasins 102 and 103) will be conveyed via overland flow and gutter flow to the concrete pan on Remington Street. The flows from the neighboring Diamond Shamrock site will be routed through the proposed development and exit via the water quality extended detention pond in the southeast corner of the lot. The existing on -site concrete trickle pan in the southwest corner will be removed. The 10-year and 100-year existing and future flows are provided in the appendix and summarized in Table 3.1. Table 3.1 Drainage Summary Design Point Tributary Sub -basin Area (ac) C (2) C (100) to (2) (min) tc (100) (min) Q(2)tot (cfs) Q(100)tot (cfs) Existing H1 0.10 0.77 0.97 6.8 5.0 0.2 0.9 H2 O.20 0.87 1.00 5.0 5.0 0.5 2.0 H3 0.04 0.71 0.88 5.2 5.0 0.1 0.3 H-01 0.03 0.95 1.00 5.0 5.0 0.1 0.3 H-1 H1+H-01 0.12 0.81 1.00 5.8 5.0 0.3 1.2 H-02 0.03 0.95 1.00 5.0 5.0 0.1 0.3 H-2 H2+H-02 0.23 0.88 1.00 5.0 5.0 0.6 2.3 H-03 0.03 0.95 1.00 5.0 5.0 0.1 0.3 H-3 H3+H-03 0.07 0.81 1.00 5.0 5.0 0.2 0.7 Total flows leaving site= 1.01 4.2 Proposed 1 101 0.09 0.51 0.64 5.0 5.0 0.1 0.6 102 0.20 0.76 0.95 5.0 5.0 0.4 1.9 103 0.05 0.69 0.87 5.0 5.0 0.1 0.4 OS-1 0.08 0.95 1.00 5.0 5.0 0.2 0.8 2 102 + OS-1 0.28 0.82 1.00 5.4 5.0 0.6 2.8 3 102+103+OS-1 0.32 0.80 1.00 5.0 1 5.0 0.7 3.2 Total flows leaving site= 0.86 3.8 4. WATER QUALITY Historically no water quality or detention has been provided. Since this site reduces the amount of impervious area and therefore reduces the flows from the site, no detention is required for this development. Since the previous use on site was a car wash, less runoff can be expected on a day to ' day basis with fewer phosphates and other pollutants being discharged into the City sewer and stormwater system. Water quality is being provided with the re -development of this site. Runoff is being conveyed to a water quality extended detention pond as much as possible to allow sediments to settle out of the stonmwater before entering the City storm sewers. This pond is as large as the site will allow but is still less than the required volume. The pond provides 38 cubic feet of the required Final Drainage and Erosion Control Report Page 4 Swallow 8-Plex June 4, 2002 I 11 ' 267 cubic foot volume at a depth of 0.5 feet. The outlet structure is a sidewalk culvert with a metal orifice plate on the upstream side of the culvert. I 5. EROSION CONTROL 5.1 Erosion and Sediment Control Measures Erosion and sedimentation will be controlled during construction by inlet filters, silt fences, ' straw barriers, gravel construction entrances, seeding and mulching. These measures are designed to limit the overall increase in sediment yield due to construction activities as ' required by the City of Fort Collins. During overlot and final grading, the soil will be roughened and furrowed perpendicular to the prevailing winds. The required erosion control ' escrow is $2,202.25. The erosion control cost estimate, effectiveness calculations and a construction schedule are included in the Appendix. Water quality will be controlled by ' routing as much runoff as possible through grass swales and in sheet flow across proposed landscape areas. I5.2 Dust Abatement ' During the performance of the work required by these specifications or any operations appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the contractor shall furnish all labor, equipment, materials, and means required. The Contractor shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance, and to prevent dust nuisance that has originated from his operations from damaging crops, ' orchards, cultivated fields, and dwellings, or causing nuisance to persons. The Contractor will be held liable for any damage resulting from dust originating from his operations under Ithese specifications on right-of-way or elsewhere. 5.3 Tracking Mud on City Streets It is unlawful to track or cause to be tracked mud or other debris onto city streets or rights -of - way unless so ordered by the Director of Engineering in writing. Wherever construction vehicles access routes or intersect paved public roads, provisions must be made to minimize ' the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. Stabilized construction entrances are required per the detail shown on the Erosion Control ' Final Drainage and Erosion Control Report Page 5 Swallow 8-Plex June 4, 2002 Plan, with base material consisting of 6" coarse aggregate. The contractor will be ' responsible for clearing mud tracked onto city streets on a daily basis. ' 5.4 Maintenance All temporary and permanent erosion and sediment control practices must be maintained and repaired as needed to assure continued performance of their intended function. Straw bale dikes or silt fences will require periodic replacement. Sediment traps (behind straw bale ' barriers) shall be cleaned when accumulated sediments equal approximately one-half of trap storage capacity. Maintenance is the responsibility of the developer. 5.5 Permanent Stabilization ' All soils exposed during land disturbing activity (stripping, grading, utility installations, stockpiling, filling, etc.) shall be kept in a roughened condition by ripping or disking along land contours until mulch, vegetation or other permanent erosion control is installed. No soils in areas outside project street rights of way shall remain exposed by land disturbing ' activity for more than thirty (30) days before required temporary or permanent erosion control (e.g. seed/ mulch, landscaping, etc.) is installed, unless otherwise approved by the Stormwater Utility. Vegetation shall not be considered established until a ground cover is ' achieved which is demonstrated to be mature and stable enough to control soil erosion as specified in paragraph 11.3.10 of the City of Fort Collins Storm Drainage Construction ' Standards. 1 I Final Drainage and Erosion Control Report ' Swallow 8-Plex Page 6 June 4, 2002 5. REFERENCES ' 1. City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards" (SDDCCS), May 1984. 2. "Final Report for Hydrologic Model Update for the Foothills Basin Master Drainage Plan", July 15, 1999, Anderson Consulting Engineers. ' 3. Soil Survey of Larimer County Area, Colorado. United States Department of ' Agriculture Soil Conservation Service and Forest Service, 1980. 4. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria Manual", Volumes 1 and 2, dated March 1969, and Volume 3, dated September 1992. Final Drainage and Erosion Control Report Page 7 Swallow 8-Plex June 4, 2002 APPENDIX A PR SPECT ROAD fEC4 , ly, ._b.t s..Ml so S: Dr �c S: vt 1 9 ti Wmc mc e D. �lg C, .. ...... . . ......... OJK ARK Rd e CNP... st �3 Yd. Wy c It ct a 2 ct C=AR,(— and o, WC' IRD� KE ROAD R. . ......................... ..................... .. . ........ .. ........ . .. ....................................... ....... ol kol, y E ct On 0.11 2- 07 E u C, Rd c a ct r Ct cl W. P. 0, SIT t m CWk ciz D, M Afr�dl t 21 • c E [HQfiSEMOTH Kip.lm .. ............. ... 15 1 wbly VICINITY MAP N. T. S. ci .10 lznc C SOILS MAP Larimer County Area, Colorado ' 12 1 t 1 1 1 SOIL SURVEY sloping to strongly sloping soil is on terrace edges, fans, and benches. This soil has a profile similar to the one described as representative of the series, but the combined thickness of the surface layer and subsoil is about 18 to 19 inches. Included with this soil in mapping are some areas of soils that are more sloping and some areas of soils that have a surface layer of sandy loam. Also included are small areas of Larimer, Stoneham, and Larim soils. Runoff is medium, and the hazard of erosion is mod- erate to severe. This soil is suited to wheat and barley under dryland management. If irrigated, it is also suited to alfalfa. It is well suited to pasture and native grasses. Capabil- ity units IVe-1, irrigated, and IVe-3, dryland; Loamy Plains range site; windbreak suitability group 1. 3—Altvan-Satanta loams, 0 to 3 percent slopes. This complex consists of nearly level soils on terraces and high benches. It is about 45 percent Altvan loam and about 30 percent Satanta loam. The soils are inter- mingled throughout the mapped areas, but Altvan loam commonly is more sloping and Satanta loam is more nearly level and is in some depressions. The Altvan soil has a profile similar to the one described as representative of the Altvan series, but the surface layer commonly is about 8 to 11 inches thick and is loam or sandy loam. The Satanta soil, has a profile similar to the one described as representative of the Satanta series, but the surface layer is about 8 to 11 inches thick and is sandy loam in places. In places both soils are redder than is typical of their respective series. Included with these soils in mapping is about 15 percent Nunn soils. Runoff is slow to medium, and the hazards of wind and water erosion are slight to moderate. If irrigated, these soils are suited to corn, sugar beets, dry beans, alfalfa, and small grain. Under dry - land management they are suited mainly to wheat, but other small grain, such as barley and oats, is some- times grown. The soils are also well suited to pasture and native grasses. Capability units IIIe-3, irrigated, and IIIe-6, dryland; Loamy Foothill range site; wind- break suitability group 1. 4—Altvan-Satanta loams, 3 to 9 percent slopes. This complex consists of gently sloping or strongly sloping soils on high terraces, benches, and fans. It is about 55 percent Altvan loam and 35 percent Satanta loam. Altvan loam is mainly more sloping, and Satanta loam is smoother. These soils have profiles similar to the ones described as representative of their respective series, but the surface layer is sandy loam and loam and the surface layer and subsoil are thinner. Many areas of both soils are redder than is typical of their respective series. Included with these soils in mapping is about 10 percent Nunn and Larimer soils. Runoff is medium to rapid, and the hazards of wind and water erosion are moderate. If irrigated, these soils are well suited to alfalfa, small grain, and pasture. Under dryland management they are suited to wheat and barley. They are also suited to pasture and native grasses. Capability units IVe-1, irrigated, and IVe-3, dryland; Loamy Foothill range site; windbreak suitability group 1. Aquepts, Loamy 5=Aquepts, loamy. These nearly level or gently sloping, poorly drained soils are in depressional areas on uplands, along drainageways, and on side slopes below large canals. The surface layer is fine sandy loam, loam, or clay loam. The underlying layer is mainly loam or clay loam extending to a depth of 40 to 60 inches or more. A water table is at or near the surface in spring and summer. Included with these soils in mapping are a few small areas of Stoneham, Fort Collins, and Kim soils and Nunn clay loam, wet. Runoff is slow to medium, and the hazard of water erosion is slight to moderate. These soils are suited to pasture and native grasses. A few areas are used for hay. If drained, the soils are suited to crops. The main irrigated crops are barley, corn, sugar beets, and wheat. Capability units IIIw-1, irrigated, and Vw-1, dryland; Wet Meadow range site; windbreak suitability group 5. Aquepts, Ponded 6—Aquepts, ponded. These nearly level soils are near stream channels and drainageways. A water table is at or near the surface most of the year. The soils are extremely variable. The native vegetation is mainly cattails, sedges, and rushes. These soils offer very little grazing but are suitable for wildlife habitat. Capability unit VIIIw-1, dryland; not assigned to a range site or windbreak suitability group. Ascalon Series The Ascalon series consists of deep, well drained soils that formed in mixed wind -deposited material. These soils are on uplands and foot slopes. Elevation ranges from 4,800 to 5,700 feet. Slopes are 0 to 5 per- cent. The native vegetation is mainly blue grams and other short grasses and forbs. Mean annual precipita- tion ranges from 13 to 15 inches, mean annual air temperature ranges from 481 to 50°.F, and the frost - free season ranges from 135 to 150 days. In a representative profile the surface layer is brown sandy loam about 6 inches thick. The subsoil is brown and pale brown sandy clay loam about 14 inches thick. The underlying material is pale brown or very pale brown sandy loam. Permeability is moderate, and the available water capacity is.medium to high. Reaction is neutral above a depth of about 16 inches and moderately alkaline below that depth. These soils are used mainly for irrigated and dry - farmed crops. Some small areas are used for native grasses. Representative profile of Ascalon sandy loam, 0 to 3 percent slopes, in a cultivated area, about 400 feet east and 650 feet south of the northwest corner of sec. 36, T. 5 N., R. 68 W.: Ap-0 to 6 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 3/3) moist; weak medium subangular blocky struc- [I ' 42 1 J [1 1 1 SOIL SURVEY 4/3) moist; moderate medium and coarse prismatic structure parting to moderate medium subangular blocky; very hard, firm, very sticky and very plastic; thin nearly continuous clay films on peds; noncalcareous; mildly alkaline; clear smooth boundary. B3ca-24 to 29 inches; pale brown (10YR 6/3) clay loam, brown (10YR 5/3) moist; weak medium subangular blocky struc- ture; very hard, firm, very plastic; few thin patchy films. on ped faces; visible calcium carbonate occurring as small nodules; calcareous; moderately alka- line; gradual smooth boundary. Clca-29 to 47 inches; light yellowish brown (10YR 6/4) clay loam, dark yellowish brown (10YR 4/4) moist; massive; very hard, firm, sticky and plastic; visible calcium carbonate occurring as nodules, thin seams, and streaks; calcareous; moderately alkaline; gradual smooth boundary. C2ca-47 to 60 inches; light yellowish brown (2.5Y 6/3) clay loam, light olive brown (2.5Y 5/3) moist; massive; very hard, firm, sticky and plastic; some visible calcium carbonate but less than in the Clca horizon; calcareous; moderately alkaline. The A horizon is light clay loam or clay loam 10 to 12 inches thick in cultivated areas. The combined thick- ness of the A and B horizons ranges from 16 to 40 inches. The 132t horizon is heavy clay loam or light clay. Depth to calcareous material ranges from 10 to 30 inches. Sand and gravel are below a depth of 40 inches in some profiles. Some profiles have substrata with a redder hue. 73—Nunn clay loam, 0 to 1 percent slopes. This level soil is on high terraces and fans. This soil has a profile similar to the one described as representative of the series, but the combined thickness of the surface layer and subsoil is about 35 inches. Included with this soil in mapping are small areas of soils that are more sloping. Also included are a few small areas of Satanta, Fort Collins, and Ulm soils and a few small areas of soils that have a surface layer and subsoil of silty clay loam. Runoff is slow, and the hazard of erosion is slight. If irrigated, this soil is suited to corn, sugar beets, beans, barley, wheat, and alfalfa. Under dryland management it is suited to wheat or barley. It is also suited to pasture and native grasses. Capability units IIs-1, irrigated, and IIIo-1, dryland; Clayey Foothill range site; windbreak suitability group 1. 74—Nunn clay loam, 1 to 3 percent slopes. This nearly level soil is on high terraces and fans. This soil has the profile described as representative of the series. Included with this soil in mapping are a few small areas of soils that are more sloping or less sloping and a few small areas of soils that have a surface layer and subsoil of silty clay loam. Also included are small areas of Satanta, Fort Collins, and Ulm soils. Runoff is slow to medium, the hazard of wind erosion is slight, and the hazard of water erosion is moderate. If irrigated, this soil is suited to corn, sugar beets, beans, barley, alfalfa, and wheat. Under dryland management it is suited to wheat and barley. It is also well suited to pasture or native grasses (fig. 10). Figure 10.—Alfalfa bales on Nunn clay loam, 1 to 3 percent slopes. LARIMER COUNTY AREA, COLORADO Capability units IIe-1, irrigated, and IIIe-6, dryland; Clayey Foothill range site; windbreak suitability group 1 75—Nunn clay loam, 3 to 5 percent slo . This gently sloping soil is on high terraces and fans. This soil has a profile similar to the one described as rep- resentative of the series, but the combined thickness of the surface layer and subsoil is about 24 inches. Included with this soil in mapping are small areas of soils that are more sloping or less sloping and a few small areas of soils that have a surface layer of light clay. Also included are a few small areas of Satanta and Ulm soils. Runoff is medium. The hazard of water erosion is moderate, and the hazard of wind erosion is slight. If irrigated, this soil is suited to barley, alfalfa, and wheat and, to a lesser extent, corn, sugar beets, and beans. Under dryland management it is suited to wheat or barley. It is also well suited to pasture and native grasses. Capability units IIIe-2, irrigated, and IIIe-7, dryland; Clayey Foothill range site; windbreak suit- ability group 1. 76—Nunn clay loam, wet, 1 to 3 percent slopes. This nearly level, somewhat poorly drained soil is on low terraces and alluvial fans, commonly adjacent to drainageways. This soil has a profile similar to the one described as representative of the series, but a seasonal high water table is at a depth of 20 to 30 inches during part of the growing season. Included with this soil in mapping are a few small areas of soils that have a strongly alkaline surface layer and a few small areas of soils that are moderately well drained. Also included are a few areas of soils that have a surface layer of loam or clay and a few areas of soils that are less sloping. Runoff is slow, and the hazard of erosion is slight. This soil is suited to pasture and hay. If the water table is lowered by management practices, corn, sugar beets, wheat, and barley can be grown. Capability unit IIIw-1, irrigated; Wet Meadow range site; windbreak suitability group 5. Otero Series The Otero series consists of deep, well drained soils that formed in alluvium and wind -deposited material. These soils are on alluvial fans and terraces. Elevation ranges from 4,800 to 5,600 feet. Slopes are 0 to 15 percent. The native vegetation is mainly blue grama, needlegrass, bluestems, and some forbs and shrubs. Mean annual precipitation ranges from 13 to 15 inches, mean annual air temperature ranges from 480 to 500 F, and the frost -free season ranges from 135 to 150 days. In a representative profile the surface layer is brown sandy loam about 4 inches thick. The underlying material is pale brown sandy loam about 13 inches thick over light brownish gray sandy loam. Permeability is rapid, and the available water ca- pacity is medium. Reaction is mildly alkaline above a depth of about 4 inches and moderately alkaline below that depth. These soils are used mainly for native grasses and for dryfarmed crops. A few areas are used for ir- rigated crops. 43 Representative profile of Otero sandy loam in an area of Otero -Nelson sandy loams, 3 to 25 percent slopes, in native grass, about 300 feet south and 1,420 feet west of the northeast corner of sec. 11, T. 10 N., R. 68 W. : Al=-O to 4 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 3/3) moist; weak very fine granular structure; soft, very friable; calcareous; mildly alka- line; clear smooth boundary. Clca-4 to 17 inches; pale brown (10YR 6/3) sandy loam, brown. (10YR 5/3) moist; weak medium and coarse subangular blocky structure; hard, very friable; cal- careous; visible calcium carbonate as few soft spots; moderately alkaline; gradual smooth boundary. C2ca-17 to 60 inches; light brownish gray (10YR 6/2) sandy loam, dark grayish brown (10YR 4/2) moist; massive; hard, very friable; calcareous; visible calcium carbonate as few soft spots; moderately alkaline. The A horizon is sandy loam or fine sandy loam 8 to 12 inches thick in cultivated areas. The C horizon is sandy loam or fine sandy loam. The soil is generally calcareous throughout, but the surface layer is leached in places. Distribution of lime in the profile is erratic. Soft sandstone is at a depth of 40 to 60 inches in some profiles. 77—Otero sandy loam, 0 to 3 percent slopes. This nearly level soil is on uplands and fans. This soil has a profile similar to the one described as representative of the series, but the surface layer is about 10 to 12 inches thick. Included with this soil in mapping are some small areas of soils that have a surface layer of loam or fine sandy loam. Also included are some areas of soils that are redder and a few small areas of Ascalon, Nelson, and. Kim soils. Runoff is slow. The hazard of water erosion is slight, and the hazard of wind erosion is moderate. If irrigated, this soil is suited to corn, barley, sugar beets, wheat, and beans. Under dryland management it is suited to pasture and native grasses and, to a lesser extent, wheat and barley. Capability units IIIe-5, irrigated, and IVe-5, dryland; Sandy Plains range site; windbreak suitability group 2. 78—Otero sandy loam, 3 to 5 percent slopes. This gently sloping soil is on uplands and fans. This soil has a profile similar to the one described as representa- tive of the series, but the surface layer is about 8 inches thick. Included with this soil in mapping are a few small areas of soils that are more sloping or less sloping. Also included are some small areas of soils in which sandstone is at a depth of 40 to 60 inches and a few small areas of Ascalon, Nelson, and Kim soils. Runoff is medium, and the hazard of erosion is moderate. If irrigated, this soil is suited to barley, wheat, alfalfa, and pasture and, to a lesser extent, corn and beans. Under dryland management it is well suited to pasture and native grasses. Capability units Ille-4, irrigated, and VIe-2, dryland; Sandy Plains range site; windbreak suitability group 2. ' APPENDIX B ' HYDROLOGIC CALCULATIONS 0 1 0 J ' Q Q 51 W ' a 1 _z 0 M O w m O M M N M M M I,-N O W 7 00 OD N W O U 0 N 0 0 0 N O O C O O O N M M N N � � M � W � N (O r t0 w Q lcql I� I� O C O O O O O O O O O N O O O O O C. N E ui ui vi vi vi ci vi vi vi <i ui vi vi ui ° c U m m 0 0 0— 0 _ C DO O N O O O O O O 0 0 0 0< O .N.. U E to N to N LO 0 to N N O 6 6 M N to N F O O r 0 co 0 0 0 0 0 0 V LO r 00 0 O) O OD O O O O O O t0 O O0 O O O o o c o 0 U v r r IA A W N (D 01 In N O r m co rn eD rn ao � r m rn co ao 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O O e>• M N M M M r CA O N a0 W N V N O O O N O O O N O O N M Q O O O O O O O O O O O O O O O C � U1 N M i (A O C a w O x O x 0 x 0 o 0 0 o a x x x x} x N x M O = x N F (AW x x x 0.o N o c C N M to _ = N M N IL= J 1 1 1 1 1 RUNOFF COEFFICIENTS & % IMPERVIOUS LOCATION: Swallow 8-Plex PROJECT NO: 9116.06 COMPUTATIONS BY: A. Reed DATE: 6/4/2002 Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria Recommended % Impervious from Urban Storm Drainage Criteria Manual Streets, parking lots (asphalt) Sidewalks (concrete) Roofs Lawns (Flat <2%, sandy soil) Runoff % coefficient Impervious C 0.95 100 0.95 96 0.95 90 0.10 0 JR Engineering 2620 E. Prospect Rd., Ste. 190 Fort Collins, CO 8525 SUBBASIN DESIGNATION TOTAL AREA (ac.) TOTAL AREA (sq.ft) ROOF AREA (sq.ft) PAVED AREA (sq.ft) SIDEWALK AREA (sq.ft) LANDSCAPE AREA (sq.ft) RUNOFF COEFF. (C) % Impervious Existing On -site H1 0.10 4,197 0 Z540 781 875 0.77 78 H2 O.20 8,612 1 1,192 3,842 Z803 776 0.87 88 H3 0.04 1,654 37 531 614 472 1 0.71 70 Existing Offsite H-01 0.03 1,204 0 1,204 0 0 0.95 100 H-02 0.03 1,254 0 1,254 0 0 0.95 100 H-03 0.03 1,494 0 1,494 0 0 0.95 100 Proposed On -site 101 0.09 3,881 1,123 0 742 2,016 0.51 44 102 0.20 8,636 821 5,158 754 1,903 0.76 77 103 0.05 1,971 813 264 297 598 0.69 65 Proposed Offsite ' OS-1 0.08 3,456 0 3,456 0 0 0.95 100 Equations - Calculated C coefficients & % Impervious are area weighted C=E(Ci Ai) /At Ci = runoff coefficient for specific area, Ai Ai = areas of surface with runoff coefficient of Ci n = number of different surfaces to consider At = total area over which C is applicable; the sum of all Ai's 9116060ow.xls 1 } N ' 0 F N z i Z cc LL Z ' �U LL 7d0 t~i) W 1 F 11 Y Q W C m O N O m 0 0 0 0 O O O O d O J i m m vi vi vi In IA N N N H m N N N y E LL m 7 IN M O m O C m E y=In In IV Cr ui Y N O N O N N M m m N N m U J d N h d m d N m N d M m d m IA x m C N U C u � U + � 30 C m M N IA m N 0 O I() M O N O IA O O N N O M r M d O h M a .E o 0 0 o c o 0 0 0 o o c o 0 0 0 0 0 LL J d IA O O d O m 0 0 O O m m N 0 m m m m _ y N N N r N N N N e- M N C N N N G N O ) Q = m m m m m m m mmN cQ0 0 0 o TP 0 0 0 o c o 0 0 o c o w K v��000lnomo0 MMv>omolnomo W J j J v � � F E --- O de In ^ 0 0 e: v N o o IA O h O O V O O NNMmOOQL J C C O IT O h p m IA m N O^ p^ J w O r lr In m m In `r° r mnmmmmmm �n mmm m w F z O O N O O M O N M M O N M O h O T O O N In O m O m N N M O O O O O O Q � v N ;:1N NMO xO Ory xO OM x O !OON M m `..cQ x S + 2+ 2+ Or+n oO m w o � x x x a + o Z Z Z w x x x N H j¢ a Ma 7 C f0 C m m N N C U 0 O LL O>> L" U O M (h N rn LL O 0 v C O Y d U t L N U V C LL O �m 0 N O 3 'E C j O O j C N Q m W z v m + C mf E o N E 11 E -" o � E N J O N w > U U z O z + m Z oil II 11 W U — — m 1 w [I 1 J } 00 a U C LL a0 N W p F x u lL 00 N _ d � 11 U } m z O F o F F W i y O 0 < o a Y f W R' m O N O m 0 O O i N IA 6 N N ~ E 1c] Iq Iq 111"] LL m d N O Cl!d M r m m N co m � O H O OO E m � GV Y rW.l O N O N N th m m N N m () J Q N r Q m Q N N N Q th m Q m N x 3 c N u 7 m n N m N m m m N N d rIN QCl N t7 N IA !✓1 U y f d N O r Q r r C O G G G G O 0 0 0 G C C O 0 0 0 0 0 O � E Q N O O d O N O O O O N m N O N m N m IJ m N N N N fV fV fV f7 N O N Cl Cl O N O Zz � Q x V m m m m m m m m m m N m m N m m m N m N K a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O .Q O G O G G G O 6 6 C C C G C G G G O O C FC N o o N o m O o m n- o- o N o N- F C7 O a^ m Nv W f M m l7 m m M m t0 O N n O N O d W v _ J H Z d r O r d N 7 M N d N O N N N O N m O m 0 0 O N O O U) O N G O N O N N M m O O O N O N O �C < W J U n n N N m m m N N O m m M w in r m m m m 2 H O O d f7 N N t7 r m O N m m N N V N v `-' a. N O O O N O O O N O O N t7 Q 0 0 0 0 0 0 0 0 0 O O 0 0 0 O Z Q 0 N N O N O N O po 0 o o m �xS2x0 co O0 0 w x x x a o N co o z z ~ c� m r �a = x x N N G w O m O O r z _O F Q N N z i z C' W LL z 00 G LL �0 m W H Y f W LL' 0 0 0 0 0 0 0 0 0 O O 0 0 o O LL m m m N O O) Z w E � Q m ti 0 X O N O N N lh m m N m m UN LU J e N n Q m Q N m N Q M T Q m m S C N U cc 0 u O Q O m N m Q m Q m N m m m N Q m O N Q rO 3 00 G G .= o o G C 0 0 0 0 0 O E Till: IR LL J a m o o Q o m o 0 0 o m m m o m rn m rn m a A fV fV tV N N N fV t7 fV G lV fV N O N O i S U m m m m m m m m m m in m m m m m m m m m C O 0 0 0 0 0 0 0 0 0 0 G G O O O O O O C O C W m fD 0 o m O m 0 0 M f+> m O m O m O O � N � p o e W O am O O O O O O O O n s� m O N O m 0 C'1 In m lh m(DONn N O Q W �� v m T J F � m aormmmrnm� �1011,11 CofV � N O � O �- O � � E O N m 0 CR O 719 O m O O m 0 m m O« V fV Q Q 1(7 O m Q O Q G 0 o m O m O N N th m O O O m O m 0 cC Q J G r O m o 0 0 0 0 0 in n o 0 0 z m o m o 0 0 0 0 o m m o 0 0 5 � o C U W r r m m m m m !n m N O .-. m m � !T 0 m a.G O CC!Ul G O m a.G m n O m O m C m G m O f � z� O O N Q lh O M r A O m m m N N U N O O O O O a C N N O O 0 O 0 O C N O 0 O 0 C N G th O 0 oy� o m �. .x2xxQx020x =+ x x ao 0 coW ry M } x x = a O ry U) o z a z 0z m H In O x S x N th y o W p a (0 7 C (0 2 C fA d m C O U C LL O U O C) A N 7 07 LL 0 m v C O Y O_ y N L N U U C j .N U O LL O N O L_ N m 3 m E C '- O 7 O 7 7 W � � m + C m" E C Q Ln EE 11 EEE U 0 J O C >w U U z 0 Q + 00 (7 IU u u w RATIONAL METHOD PEAK RUNOFF (City of Fort Collins, 2-Yr Storm) LOCATION: Swallow 8-Plex PROJECT NO: 9116.06 COMPUTATIONS BY: A. Reed DATE: 6/4/2002 2 yr storm, Cf = 1.00 JR Engineering 2620 E. Prospect Rd., Ste. 190 Fort Collins, CO 80525 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Design Point Tributary Sub -basin A (ac) C Cf tc (min) i (in/hr) Q (2) (cfs) from Design Point Q (2) (cfs) Q(2)tot (cfs) Existing 1-11 0.10 0.77 6.8 2.56 0.19 0.19 H2 O.20 0.87 5.0 2.85 0.49 0.49 H3 0.04 0.71 5.2 2.76 0.07 0.07 H-01 0.03 0.95 5.0 2.85 0.07 0.07 H-1 H1+H-01 0.12 0.81 5.8 2.69 0.27 0.27 H-02 0.03 0.95 5.0 2.85 0.08 0.08 H-2 H2+H-02 0.23 0.88 6.0 2.85 0.57 0.57 H-03 0.03 0.95 5.0 2.85 0.09 0.09 H-3 H3+H-03 0.07 0.81 5.0 2.85 0.17 0.17 Proposed 1 101 0.09 1 0.51 5.0 2.85 0.13 1 1 0.13 102 0.20 0.76 5.0 2.85 0.43 0.43 103 0.05 0.69 5.0 2.85 0.09 0.09 OS-1 0.08 0.95 5.0 2.85 0.21 0.21 2 102 + OS-1 0.28 0.82 5.4 2.74 0.62 0.62 3 102+103+OS-1 0.32 0.80 5.0 2.85 0.74 0.74 Q=CfCiA Q = peak discharge (cfs) C = runoff coefficient Cf = frequency adjustment factor i = rainfall intensity (in/hr) from City of Fort Collins OF curve (4/16/99) A = drainage area (acres) i = 24.221 / (10+ tc)09 911606now.xls RATIONAL METHOD PEAK RUNOFF (City of Fort Collins, 10-Yr Storm) LOCATION: Swallow 8-Plex PROJECT NO: 9116.06 COMPUTATIONS BY: A. Reed DATE: 6/4/2002 10yrstorm, Cf= 1,00 JR Engineering 2620 E. Prospect Rd., Ste. 190 Fort Collins, CO 80525 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Design Point Tributary Sub -basin A (ac) C Cf tc (min) i (inthr) Q (10) (cfs) from Design Point Q (10) (cfs) Q(10)tot (cfs) Existing H1 0.10 0.77 6.8 4.37 0.33 0.33 H2 O.20 0.87 5.0 4.87 0.84 0.84 H3 0.04 0.71 5.2 4.72 0.13 0.13 H-01 0.03 0.95 5.0 4.87 0.13 0.13 H-1 Hi+H-01 0.12 1 0.81 5.8 4.59 0.46 1 0.46 H-02 0.03 1 0.95 5.0 4.87 0.13 0.13 H-2 1-12+1-1-02 0.23 1 0.88 5.0 4.87 0.97 0.97 H-03 0.03 0.95 5.0 4.87 0.16 0.16 H-3 H3+H-03 0.07 0.81 5.0 4.87 0.29 0.29 Proposed 1 101 0.09 0.51 5.0 4.87 0.22 0.22 102 0.20 0.76 5.0 4.87 0.74 0.74 103 0.05 0.69 1 5.0 1 4.87 1 0.15 0.15 OS-1 0.08 0.95 5.0 1 4.87 1 0.37 0.37 2 102 + OS-1 ' 0.28 1 0.82 5.4 4.67 1.1 1.06 3 102+103+OS-1 0.32 0.80 5.0 4.87 1.26 1 1.26 Q=CtCiA Q = peak discharge (cfs) C = runoff coefficient Ct = frequency adjustment factor i = rainfall intensity (in/hr) from City of Fort Collins OF curve (4/16/99) A = drainage area (acres) I = 41.44 f (10+ tC)° 7914 9116068ow.xls RATIONAL METHOD PEAK RUNOFF (City of Fort Collins, 100-Yr Storm) LOCATION: Swallow 8-Plex PROJECT NO: 9116.06 COMPUTATIONS BY: A. Reed DATE: 6/4/2002 100 yr storm, Cf = 1.25 JR Engineering 2620 E. Prospect Rd., Ste. 190 Fort Collins, CO 80525 DIRECT RUNOFF CARRY OVER TOTAL REMARKS Des. Point Area Design. A (ac) C Cf tc (min) i (in/hr) Q (100) (cfs) from Design Point Q (100) (CIS) Q(100)tot (cfs) Existing HI 0.10 0.97 5.0 9.95 0.93 0.93 H2 O.20 1.00 5.0 9.95 1.97 1.97 H3 0.04 0.88 5.0 9.95 0.33 0.33 H-01 0.03 1.00 5.0 9.95 0.27 0.27 H-1 H1+H-01 0.12 1.00 5.0 9.95 1.23 1.23 H-02 - 0.03 1.00 5.0 9.95 0.29 0.29 H-2 H2+H-02 0.23 1.00 5.0 9.95 2.25 2.25 H-03 0.03 1.00 5.0 9.95 0.34 0.34 H-3 H3+H-03 0.07 1.00 5.0 9.95 0.72 0.72 Proposed 1 101 0.09 0.64 5.0 9.95 0.56 0.56 102 0.20 0.95 5.0 9.95 1.88 1.88 103 0.05 0.87 5.0 9.95 0.39 0.39 OS-1 0.08 1.00 5.0 9.95 0.79 0.79 2 102 + OS-1 0.28 1.00 5.0 9.95 2.76 2.76 3 102+103+OS-1 0.32 1.00 5.0 9.95 3.21 3.21 Q=CIA Q = peak discharge (cfs) C = runoff coefficient i = rainfall intensity (in/hr) from City of Fort Collins OF curve (4/16/99) A = drainage area (acres) i = 84.682 / (10+1c)o"15 911606now.xis I 1 1 1 1 1 APPENDIX C HYDRAULIC CALCULATIONS I Swale Sizing Worksheet for Triangular Channel Project Description Project File x:\3910000.all\3911606\9116dr.fm2 Worksheet Side Lot Swale Flow Element Triangular Channel Method Manning's Formula Solve For Channel Depth Input Data Mannings Coefficient 0.060 Channel Slope' 0.013600 ft/ft Left Side Slope 4.000000 H : V Right Side Slope 4.000000 H : V Discharge 2.00 cfs Results Depth 0.62 ft Flow Area 1.54 ftz Wetted Perimeter 5.12 ft Top Width 4.97 ft Critical Depth 0.43 ft Critical Slope 0.090847 ft/ft Velocity 1.30 ft/s Velocity Head 0.03 ft Specific Energy 0.65 ft Froude Number 0.41 Flow is subcritical. osn 7fo1 03:13,22 PM Haeslad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 FlowMaster v5.15 Page 1 of 1 Curb Cut ' Worksheet for Rectangular Channel 1 1 Project Description Project File x:\3910000.all\3911606\9116dr.fm2 Worksheet Curb Cut Flow Element Rectangular Channel Method Manning's Formula Solve For Channel Depth Input Data Mannings Coefficient 0.013 Channel Slope 0.020000 ft/ft Bottom Width 2.00 ft Discharge 2.80 cfs Results 1 Depth 0.25 ft Flow Area 0.50 ft2 Wetted Perimeter 2.50 ft Top Width 2.00 ft Critical Depth 0.39 ft Critical Slope 0.005231 ft/ft ' Velocity 5.55 ft/s Velocity Head 0.48 ft Specific Energy 0.73 ft Froude Number 1.95 Flow is supercritical. I 1 H 1 01 /23/02 09:05:38 AM Haestad Methods. Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 FlowMaster v5.15 Page 1 of 1 I APPENDIX D - WATER QUALITY 1 J Fi I JR Engineering 1 1 1 1 WATER QUALITY CAPTURE VOLUME SUMMARY FOR EXTENDED DETENTION PROJECT NAME: Swallow 8-Plex JR PROJECT NO: 39116.06 COMPUTATIONS BY: A Reed DATE: 6/4/2002 Guidelines from Urban Strom Drainage Criterial Manual, September 1999 (Referenced figures are attached at the end of this section) Use 40-hour brim -full volume drain time for extended detention basin Water quality Capture Volume, WQCV = 1.0 * (0.91 * i3 - 1.19 * iZ + 0.78i) Design Volume: Vol = WQCV/12 * Area * 1.2 MAJOR BASIN Trib. area (acres) Impervious Ratio, la % Impervious I = la/100 WQCV (watershed inches) Design Volume, Vol. (ac-ft) POND A 0.20 77 0.77 0.31 0.006 911606wq.XLS,6/3/2002,8:06 AM Swallow Office Water Quality Pond Proposed Detention Pond - Stage/Storage LOCATION: Swallow 8-Plex PROJECT NO: 39116.06 COMPUTATIONS BY: A Reed SUBMITTED BY: JR ENGINEERING DATE: 6/4/2002 V = 1 /3 d (A + B + sgrt(A*B)) where V = volume between contours, ft3 d = depth between contours, ft A = surface area of contour Swallow Office Water Qualitv Pond pond inv top of berm - Stage (ft) Surface Area W) Incremental Storage (ft) Total Storage (ft) Total Storage (ac-ft) 5018 0 5018.1 10 0 0 0.000 5018.2 54 3 3 0.000 5018.3 107 8 11 0.000 5018.4 128 12 23 0.001 5018.5 168 15 38 0.001 Required WQCV = 0.006 ac-ft = 267 ft3 WQCV Provided = 0.001 ac-ft 38 ft3 911606wq.XLS I t Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility POND A Project Name: Swallow 8-Plex Project Number: 39116.06 Company: JR Engineering Designer: A Reed Date: 6/4/2002 1. Basin Storage Volume A) Tributary Area's Imperviousness Ratio (i=ljl00) ' B) Contributing Watershed Area (Area) C) Water Quality Capture Volume (WQCV) ' (WQCV = 1.0 - (0.91 ' i3 - 1.19 ' i2 + 0.78i) ) D) Design Volume: Vol = WQCV/12Area 1.2 2. Outlet Works A) Outlet Type (Check One) ' B) Depth at Outlet Above Lowest Perforations (H) C) Required Maxiumum Outlet Area per Row, (Ao) ' (Figure EDB-3) D) Perforation Dimensions (enter one only) i) Circular Perforation Diamter OR ii) 2" Height Rectangular Perforation Width 1 E) Number of Columns (nc, See Table 6a-1 for Maximum) F) Actual Design Outlet Area per Row (AJ G) Number of Rows (nr) H) Total outlet Area (Ao,) Note: No trash rack is required for this design. le = 76.67 % i = 0.7667 A = 0.20 acres WQCV = 0.31 watershed inches Vol. = 0.006 ac-ft = 266.52 ft3 x Orifice Plate Perforated Riser Pipe Other: H = 0.5 ft Ao = 0.18 square inches D = 7116 inches, OR W = inches nc = 1 number Ao = 0.15 square inches nr = 6 number Aot = 0.9 square inches ' Page 1 1 1 1 1 1 1 1 1 i U co W Lj r `O F— cc o � N Of cn Fw- U W Q O O O O "O Z a O v� \ uO V e 0 CL F C u co I APPENDIX E ' EROSION CONTROL 1 11 ' JR Engineering, Ltd. 2620 E. Prospect Rd., Ste. 190, Fort Collins, CO 80525 [1 1 RAINFALL PERFORMANCE STANDARD EVALUATION PROJECT: Swallow 8-Plex STANDARD FORM A COMPLETED BY: A. Reed DATE: 04-Jan-02 DEVELOPED ERODIBILITY Asb Lsb Ssb Ai • Li At • Si Lb Sb PS SUBBASIN(s) ZONE (AC) (FT) (%) (FT) (%) (%) 101 MODERATE 0.09 141 2.7 12.6 0.2 102 MODERATE 0.20 136 1.4 27.0 0.3 103 MODERATE 0.05 92 2.3 4.2 0.1 Total 0.29 43.69 0.62 152 2.1 79.2% Ash = Sub -basin area Lsb = Sub -basin flow path length ' Ssb = Sub -basin slope Lb = Average flow path length = sum(Ai Li)/sum(Ai) Sb = Average slope = sum(Ai Si)/Sum (Ai) PS is taken from Table 8-a (Table 5.1, Erosion Control Reference Manual) by interpolation. An Erosion Control Plan will be developed to contain PS% of the rainfall sedimentation that would normally flow off a bare ground site during a 10-year, or less, precipitation event. 1 r 1 ' Erosion.xls I JR Engineering 2620 E. Prospect Rd., Ste. 190, Fort Collins, CO 80525 EFFECTIVENESS CALCULATIONS PROJECT: SWALLOW 8-PLEX STANDARD FORM B COMPLETED BY: A. Reed DATE: 04-Jun-02 EROSION CONTROL C-FACTOR P-FACTOR METHOD VALUE VALUE COMMENT BARE SOIL 1.00 1.00 SMOOTH CONDITION ROUGHENED GROUND 1.00 0.90 ROADS/WALKS 0.01 1.00 GRAVEL FILTERS 1.00 0.80 PLACED AT INLETS SILT FENCE 1.00 0.50 SEDIMENT TRAP 1.00 0.50 STRAW MULCH (S = 1-5%) 0.06 1.00 FROM TABLE 8B STRAW BARRIERS 1.00 0.80 EFF = (1-C*P)*100 MAJOR SUB BASIN AREA EROSION CONTROL METHODS BASIN BASIN (Ac) 101 0.09 ROADS/WALKS 0.02 Ac. ROUGHENED GR. 0.03 Ac. STRAW/MULCH 0.05 Ac. GRAVEL FILTER NET C-FACTOR 0.32 NET P-FACTOR 0.49 EFF = (1-C*P)*100 = 84.3% 102 0.20 ROADS/WALKS 0.14 Ac. ROUGHENED OR. 0.02 Ac. STRAW/MULCH 0.04 Ac. GRAVEL FILTER NET C-FACTOR 0.12 NET P-FACTOR 0.40 EFF = (1-C*P)*100 = 95.4% 103 0.05 ROADS/WALKS 0.01 Ac. ROUGHENED GR. 0.02 Ac. STRAW/MULCH 0.01 Ac. GRAVEL FILTER NET C-FACTOR 0.43 NET P-FACTOR 0.48 EFF = (1-C*P)* 100 = 79.2% TOTAL AREA = 0.33 ac TOTAL EFF = 90.3% ( E (basin area * eff) / total area REQUIRED PS = 79.2% Since 90.3% > 79.2%, the proposed plan is o.k. 911606er.xls PAGE 23 I O I C 1 C l (D C C I I O L n 1 I c Q Ln Ln Lr) I 1 g q co co co i 1 C 1 I Ctm mC1(= (--CDCD I G 1 c 1 I c c c c lTi lS") lr 117 l!-: L.f) I I CC d co d d d d co co co I 1 C I I 1 coM Cli m m 01 CLmcolm C\ (7)COC 1 I M I I rcccccc cIn Ln tr 1 I al co co al co on co g co co co co al co x 1 C i I i nal co co C'. m ON 471m Cl m mQ: Cla C)C1 C) mm 1 - I O l c c ct c c c c c c c c c c c c c c c c c 1 I N I g CO CO CO CO CO d co cod d co co d cc co co co co co 1 I I O 1 I CMcLncootDLo r,-r-r t� r r-r�I r,r,cococococod 1 . 1 O 1 I c c r. c c c c c c c c c c c c c c -:I- I CC CO co CO co CO d d co d d cc -` co d C.^ CO Co d d d CO d d d co d 1 1 G i O I i dNM Ln LP L1-: lD LD lD t0 LO lO t\ n r\ f\ t\ f-- � ^^nq cod I M 1 C1 C 1 CCcc�•c Gfccccc I I cocococococo co co co co co co co g q co d co co co co co CO al co co I O I O J 1 1 I LO OzrLn In Lo Ln LD LD LD LD LC LD LD co LO LD r- n f., r\ r., r� 1 1 O U I 1 c :cccccccccC'c7-�Cf���C'Q'ci I I cog co co al M coco coco q co al coco q CO co co co al d d co co co I I ^ 1 O N I I I cCI("iMMc��cl.0 Ln 11-)Lc') Lo Ln L7 Ln Ln tO LD LD LD LD LD t\ I Z 1 n 1 I M M c c c c c c c c c c c c c c c c c c c c I I--. 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W �. 1 1 NM -Ln tO f`M CnO.-I N M c Ln LO 1- COC) CD Ln CD Ln C Ln CD c LO r C-� `1 ' TABLE 5.1 t CONSTRUCTION SEQUENCE STANDARD FORM C PROJECT: Swallow 8-Plex COMPLETED BY: A. Reed DATE: 04-Jun-02 Indicate by use of a bar line or symbols when erosion control measures will be installed. Major modifications to an approved schedule may require submitting a new schedule for approval by the City Engineer. MONTH 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 10 11 12 Demolition Grading Wind Erosion Control: Soil Roughing Perimeter Barrier Additional Barriers Vegetative Methods Soil Sealant Other Rainfall Erosion Control Structural: Sediment Trap/Basin Inlet Filters Straw Barriers Silt Fence Barriers W ELM Sand Bags Bare Soil Preparation Contour Furrows Terracing Asphalt/Concrete Paving Other Vegetative: Permanent Seed Planting Mulching/Sealant Temporary Seed Planting Sod Installation Nettings/MaL%tBlankets Other BUILDING CONSTRUCTION -f*ffi STRUCTURES: INSTALLED BY: CONTRACTOR MAINTAINED BY: DEVELOPER VEGETATION/MULCHING CONTRACTOR: TO BE DETERMINED BY BID DATE SUBMITTED: APPROVED BY CITY ON: 911606er.xis,6/3/2002 1 1 1 t 1 SWALLOW 8-PLEX EROSION CONTROL COST ESTIMATE JOB NO. 9116.06 EROSION CONTROL MEASTTRF.S COMPLETED BY: A. Reed ITEM DESCRIPTION UNITS UNIT COST UANTITY I TOTAL COST 1 TEMPORARY SEED & MULCH ACRE $ 655.00 0.10 $ 67.92 2 SILT FENCE LF $ 3.00 299 $ 897.00 3 GRAVEL CONSTRUCTION ENTRANCE EACH $ 500.00 1 $ 500.00 4 INLET PROTECTION EACH $ 250.00 0 $ - 5 STRAW BALES LF $ 3.25 1 $ 3.25 6 SEDIMENT TRAP EACH $ 500.00 0 $ - COST $ 1,468.17 CITY RESEEDING COST FOR TOTA1. STTF. A R F A ITEM DESCRIPTION UNITS I UNIT COST lQUANTITY I TOTAL COST 1 IRESEEDMULCH ACRE $ 655.00 0.3 $ 217.86 COST $ 217.86 SECURITY DEPOSIT $ 1,468.17 REQUIRED EROSION CONTROL SECURITY DEPOSIT WITH FACTOR OF 150% $ 2,202.25 WALLOW ROAD _r______v__ BY RIQRT OF WAY L____--------------- ________ °--- ♦ \1 \ 00 0000 00 000000I Was Was simmommimm SEE WIN NEW 00 go 1 I ►• 1 .03 .95 I gWIN _ no go \ 1 Nil 1 � s � I 1 ------ ------- 11 ..— _ .—� /P! 4_ . ^ a... y.._...«. _ I t m m-.� 'M � �'-� m T missml E� I Aft Aft all/ amy1 I I/ 1 Ili* "Ifi IF ., ram/ .;,;410, soars _.. -- I 10 5 I I I SCALE ,• - tD' I I 1 I LEGEND I ' I I Q4 DESIGN POINT — BASIN CIBTERIA M ]S RUNOFF COEFFICIENT I�S F AREA IN ACRES W =1 BASIN BOUNDARY a — — — — — — EwSPNG PIPES I$Z 13 O —i 5' CONTOUR � _ ---- L�wSTNG EwsTwc 1'ca+TouR I I NOTE: SEE SHEET 4 OF 5 I FOR D AINAGE SUMMARY TABLE. 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