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Home My WebLink AboutCHASE BANK @ RIGDEN FARM - PDP - 26-09 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTCalculations Details for the erosion control measures can be found in the City of Fort Collins Erosion Control Reference Manual and are also included in the appendix. I CONCLUSION Compliance with Standards The proposed erosions control procedures for JP Morgan Chase Bank at Rigden Farms Tract A Lot 1 was designed to meet the City of Fort Collins Erosion Control Reference Manual. Drainage Concept The drainage system for JP Morgan Chase Bank at Rigden Farms Tract A, Lot 1 was designed to allow storm water to be safely conveyed through and away from the site without negatively impacting downstream or upstream properties (regionally) beyond that imposed by the historic condition. The drainage concepts proposed for this site are in accordance with those presented in previous reports. Sediment and Erosion Control Concept The construction BMP's proposed for this site follow the requirements of the City of Fort Collins. Attention to proper installation and maintenance are essential for the sediment and erosion control practices to function properly. ® Page 4 q of erosion shall be analyzed to determine if additional erosion controls are necessary. Erosion controls are shown where they are expected to be needed during the construction process and additional controls will be added as required by site or weather conditions. Excess sediment may be redistributed in stabilized native seeding areas as appropriate. Temporary structural BMP's will need to be removed and properly disposed of within 30 days following final stabilization of vegetated ground surfaces or pavement of upstream surfaces. Working in or Crossing Wetlands and Drainageways There are no wetlands within the site's property line. Detention and Water Quality Permanent Detention and Water Quality are provided off -site by the Master Plan, see Rigden Farm Filing One Drainage Report (JR Engineering 1999). Schedule See Appendix B for proposed development schedule. 4 Permanent Stabilization Measures Permanent stabilization will be achieved once the asphalt, curb and gutter, concrete sidewalks, and seeding is established providing a density of coverage equal to at least 70% of the original coverage for the disturbed area. In the interim, the erosion control measures will remain intact and maintained. Stormwater Management Considerations During the short period of time between the start of overlot grading and construction of drive aisles, silt fence will protect the off -site areas from sedimentation. The permanent interim condition of native seeding and mulching will serve to improve water quality by improving sediment deposition in Stormwater and protection of receiving waters from contamination. 41 Construction Materials and Equipment The contractor shall store all construction materials and equipment within the boundaries of the Stabilized Staging Area. All maintenance and fueling of equipment shall be confined in a bermed area that will provide containment in the event of a petroleum product spill. Maintenance The erosion control measures are to be inspected and maintained on a weekly basis by the site project superintendent during construction. Gravel inlet protection is to be checked weekly for gravel infiltration into inlets and cleaned or increased as necessary. Mulching of bare soils will be checked regularly and areas of loss or damage are to be re -mulched within seven working days as necessary. Street cleaning is to be done in a timely manner either by hand or street cleaner immediately following the deposition. Flushing of sediment with water is prohibited. Cost Estimate The estimated cost for the erosion control measures is $5,150. See Appendix B for the estimate of probable cost. 14 Page 3 F 4 4 I I following are effective BMPs (Best Management Practices) which will be utilized on site to help with erosion control. Silt Fence Silt fence is a sediment -trapping device that utilizes a special filter fabric to prevent sediments from being carried offsite by water, as described in the Erosion Control Reference Manual. Details for installing silt fences are included on the Erosion Control Detail Sheet in Appendix C. Prior to beginning any earthwork activities, silt fences will be installed as shown on the plan. The silt fence will protect the surrounding streets and drainage ways from excessive sediment buildup. The silt fence along the property boundaries shall remain in place and be regularly maintained until the temporary native seeding is established and construction activities have been completed. Inlet Protection Off -site storm inlets shall be projected with gravel and wire -mesh filters or concrete blocks surrounding the inlet opening as described in the Manual. Details for the installation of inlet protection are provided in Appendix C. The filters will prevent construction -related sediment from being conveyed into the storm sewer system. The inlet protection shall be -maintained until the upstream ground surfaces have been stabilized. Vehicle Tracking Control The construction access road with an entrance onto a paved road shall be graveled for a minimum distance of 50 linear feet to retain mud and other potential pollutants on -site. An approximate thickness of 12 inches of 3 — 6 inch angular rock is required. Vehicle tracking control helps to insure that sediment from the site will not be transported to adjoining roadways. This BMP must be inspected daily. Should the BMP measure not be performing as intended and mud or soils are tracked onto paved public roads, the roads shall be cleaned as soon as possible. No construction debris, materials, or soil deposits shall be allowed to impede the smooth flow of traffic on public roads. Further BMPs may be required including Vehicle Tracking Control with Wheel Wash if Vehicle Tracking Control alone is not sufficient to protect adjoining paved roads. Surface Roughening Surface Roughening consists of cutting 2 to 4 inch deep furrows parallel to the contours. This helps to reduce runoff velocities and thereby helps to control sediment transport in freshly graded areas. All areas that will not be paved, used for building foundations, permanently sodded or landscaped within 7 days of being graded to final grade should be roughened. Seeding and Mulching Disturbed areas shall be seeded and mulched or paved within 30 days following completion of grading. Stockpiled soils that shall remain undisturbed for 30 or more days shall be temporarily seeded and mulched with a non -irrigated native grass seed mix. Surfacel roughening in large, sloping areas is preferable to smooth grading for preventing sediment from being eroded and carried off -site by wind or water erosion. Maintenance and Removal of Erosion Controls Structural and vegetative erosion control BMP's will be inspected after every significant precipitation event or snowmelt or at least once every week to confirm that they are properly installed and operational. Replace or repair gravel filters and silt fences as needed: Excess sediment shall be removed periodically from collection points to maintain a minimum of 75 percent maximum storage capacity•at all times. Areas showing initial signs a - R Page 2 INTRODUCTION This report presents the JP Morgan Chase Bank at Rigden Farms Tract A, Lot 1 preliminary erosion control report. The design and analysis of this site has been performed in accordance with the City of Fort Collins Erosion Control Reference Manual. Drawings, tables, and design calculations are included in the appendix of this report. Site Location The site is a portion of Tract A, Rigden Farms Filing Number One, located in Northwest Quarter of Section 29, Township 7 North, Range 68 West of the 6'h Principal Meridian, City of Fort Collins, County of Larimer, State of Colorado. More specifically it is located south of Custer Drive; west of Timberline Road and east,of Illinois Drive. Adjacent developments include a commercial shopping center to the north, undeveloped lots to the east, a church to the south and a residential subdivision to the west. NSite Description The site is approximately 0.885 acres in size. The topography for the site generally slopes southeasterly at slopes ranging from 0.5% to 2.0%. The soils within the site are Nunn clay loam and fall into Hydrologic soils group Type C. The vegetation is native grasses and weeds. Proposed Project Description The project is a proposed commercial development. The proposed site will consist of one commercial building (a bank), an automated teller machines, drive-thru banking lanes, parking spaces, drive aisles and landscaped areas. EROSION AND SEDIMENT CONTROL PLAN Volumes and Areas Impacted The grading operations for this project will disturb approximately 0.885 acres. Cuts and fills ranging from +1 to +3 feet are expected during grading operations. Once the grading is complete, the site will be stabilized with seeding and mulching. Refer to the plans for location and limits of the grading operations. The erosion potential for the site will vary at different stages of construction. The initial earthwork operations will remove topsoil and vegetation. This will expose bare earth to rainfall erosion and wind erosion. As grading operations progress for cuts and fills, compaction and wetting will reduce wind and rain erosion. Once grading is complete, all prescribed measures will be implemented to limit sediment discharge off -site. Installation of limited curb and gutter, pavement for the proposed drive aisles, and temporary seeding will further reduce erosion potential. Erosion and Sediment Control Measures The entire site shall be graded in preparation for development. Drive aisles will be paved and landscaping will minimize wind and water erosion. The methods used to control erosion and sediment during development of the subject property will comply with the City of Fort Collins Erosion Control Reference Manual (January 1991). The predominant pollution expected at the site during construction and under permanent conditions is sediment in storm water runoff. The Page 1 f] Index of Figures All figures are presented in the appendices Appendix A Vicinity Map Soils Map Appendix B Erosion Control Calculations Erosion Control Probable Cost Proposed Development Schedule Appendix C Erosion Control Details LI Page 11 F TABLE OF CONTENTS q INTRODUCTION........................................................................................1 SiteLocation...........................................................................................................................1 SiteDescription.......................................................................................................................1 Proposed Project Description..................................................................................................1 EROSION AND SEDIMENT CONTROL PLAN ..........................................1 Volumesand Areas Impacted.................................................................................................1 Erosion and Sediment Control Measures................................................................................1 Schedule.................................................................................................................................3 Permanent Stabilization Measures......................................................................................>...3 Stormwater Management Considerations...............................................................................3 Construction Materials and Equipment....................................................................................3 Maintenance...........................................................................................................................3 CostEstimate.....................................................................................................................:..3 Calculations............................................................................................................................4 I I I CONCLUSION........................................................................................... 4 Compliancewith Standards....................................................................................................4 DrainageConcept...................................................................................................................4 Sediment and Erosion Control Concept..................................................................................4 REFERENCES...................:....................................................................... 5 ® Pagel CLC ASSOCIATES EROSION CONTROL REPORT FOR JP MORGAN CHASE BANK AT RIGDEN FARMS TRACT A, LOT 1 CITY OF FORT COLLINS, COLORADO