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HomeMy WebLinkAboutHARMONY RIDGE P.U.D. SECOND REPLAT (SIX PLEX), 4608 DUSTY SAGE DR. - PDP/FDP - FDP150041 - REPORTS - EROSION CONTROL LETTER/REPORT141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Erosion Control Report Harmony Ridge 6-Plex 4608 Dusty Sage Drive Fort Collins, CO 80524 a. Site Description: a. Nature of Construction Activity Ridgeview Business Ventures owns lot 15, Harmony Ridge P.U.D. Located in the east half of the northwest quarter of section 3, Township 6 North, Range 69 West of the 6 th P.M., Beg at NE Corner of lot 15: N 65 00' 06" E 12 FT; TH S 24 59' 54" E 177.18 FT; TH S 65 00' 06" W 12 FT; TH N 24 59' 54" W 177.18 FT TPOB. (Split from 9603216006)City of Fort Collins, State of Colorado. Tree Line Builders will be the general contractor on the 6 individual townhome units slated to be constructed on lot 15. Full 10’ foundation walls, stone and stucco construction, 2 hour rated demising walls and wood framed construction will produce a high end product. Six individual sewer services, one 1 ½’ water service and two separate gas services will be stubbed into the building from the utility easement on the east side of Dusty Sage Drive. Concrete driveways and landscaping is included in Tree Line’s scope of work. Excavation of 4608 Dusty Sage will be accomplished in two separate phases. i. Proposed Sequence of Major Activities Approximately a 60’x180’ stretch of lot 15 will be excavated first allowing the basement foundations to formed and poured. This 10,800 sq. ft. area of disturbance will consist approximately a 9’ dig with over 4000 cubic yards of soil be removed. Spoils from Lot 15 will be hauled to lot 13 in Harmony Ridge, one lot to the south on Dusty Sage Drive. Spoils from lot 15’s foundation excavation will be hauled and piled on lot 13 in Harmony Ridge. The majority of the spoils on lot 13 will permanently stay there to adjust the 5’ of elevation change on lot 13. The remainder will be temporary stored on lot 13 until such point that the foundations on lot 15 are ready to be backfilled and compacted. Once the foundations have been backfilled on lot 15, the excavation of the garages will take place. An additional 25’x180’ stretch of lot 15 will be excavated to allow for the garage walls to be formed and poured. The spoils from this 4500 sq. ft. area of disturbance will once again be hauled down the street to lot 13. Until such point that the garages on lot 15 are ready to be backfilled. Area of Disturbance: The total area of disturbance on lot 15 is roughly a .367 of an acre for both the foundation walls and the garage walls. See attached site plan and updated plat. Soil Description: See attached soils report for lot 15 Harmony Ridge. Existing Vegetation: Prior to any construction activity lot 1 was seeded and regularly maintained as it was an extension of the Harmony Ridge green belt it backs up too. 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Location of Potential Pollution Sources: See Figure 1 for phase 1 excavation location and area of disturbance. See Figure 2 for Phase 2 excavation location and total area of disturbance. See Figure 3 for location of stored soils and loading and unloading operations. See Figure 5 for location of onsite waste management practices including temporary sanitation facilities. Closest Receiving Waters/Path of Travel: The closest receiving waters is the Trilby Lateral running through the Cathy Fromme Prairie area. The path of travel is shown through the Harmony Ridge P.U.D. grading plan, also showing storm water inlets within Harmony Ridge. The closest receiving storm water inlets and the path of travel is illustrated in Figure 6. SWMP Administrator: The SWMP Administrator for 4608 Dusty Sage Drive is responsible for developing, maintaining and revising the SWMP as needed throughout construction. Ed Glavin – Superintendent Tree Line Builders Fort Collins, CO Office: (970) 493-9127 Mobile: (815) 403-8363 Email: Ed@treelinebuilt.com Identification of Potential Pollutant Sources: The following activities and pollutant sources were evaluated:  Disturbed and stored soils;  Vehicle tracking controls;  Management of Contaminated soils;  Loading and unloading operations;  Outdoor Storage activities;  Vehicle and equipment maintenance and fueling;  Dust or particulate generating processes or activities; 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127  Routine maintenance activities;  On site waste management practices  Concrete truck washing;  Dedicated concrete and asphalt batch plants;  Non-industrial waste sources;  Potential spills; 1. Disturbed and stored soils: a. Through a two phase excavation operation Tree Line Builders intends to mitigate the impact of un-stabilized disturbed soil in the storm water system of Harmony Ridge. The initial phase of excavation will be the bulk of the spoils leaving the site. Approximately 4000 cubic yards of soil will be hauled off lot 15 down the Dusty Sage Drive to lot 13, where the soil will remain until the foundations are ready to be backfilled. Lot 13 has silt fence installed around the perimeter to contain any run off from the un-stabilized stock pile. b. Once the foundations are ready to backfill, soil from lot 13 will be hauled back to lot 15. The foundations will be backfilled and excavation of the garages will immediately follow. Once again hauling the spoils to the remaining stockpile on lot 13. At such point that the garages are ready to be backfilled, once again soil will be hauled from lot 13 back to lot 15. Once lot 15 has been sufficiently backfilled the remaining soil on lot 13 will be graded out and seeded (weather dependent). Silt fence will be kept up until such point lot 13 has been deemed stable by erosion control official. 2. Vehicle Tracking Controls: a. Site fencing limits the inflow of vehicle’s traveling within the site and area of disturbance, thus limiting the tracking of soils off site. Once the garages have been excavated, poured and backfilled temporary road base will be hauled in. Placing the gravel road base where our driveways will eventually be poured will help alleviate any vehicle tracking mud off site. If excessive tracking is observed, Dusty Sage Drive will be scraped down and a street sweeper can be brought in if necessary. 3. Management of Contaminated Soils: a. According to the soils report no contaminated soils are anticipated on the excavation of 4608 Dusty Sage. If contaminates are discovered additional BMP’s will be implemented to ensure containment of any containment until such contaminant can be disposed of safely and legally. 4. Loading and Unloading Operations: a. Once again site fence limits the inflow of vehicle’s traveling within the site. Contractors will be directed to park on the N. side of 4608 Dusty Sage and driving within the site will only be on as needed basis. Trucks hauling soils off site will stay on Dusty Sage Drive as a front loader loads trucks from the side extending over the sidewalk. Thus saving the need for a tracking pad on site and any unnecessary driving on and off the site. 5. Outdoor Storage Activities: 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 a. Very few substances will be stored on site regularly, those most common include fuel and oil used for construction equipment. Other chemicals stored on site will be evaluated on an as needed basis to determine the best course of action for safe containment in the event of a spill. 6. Vehicle and Equipment Maintenance and Fueling a. Tree Line Builders does not anticipate any vehicle maintenance or fueling on site. Fueling of small construction equipment (generator, compressor, etc) will be done in an open area with no more than a 5 gallon gas tank. Any fuel or oil spill will be cleaned up and contained immediately to not allow any contaminants to make it into the storm water or the ground water. 7. Dust and Particulate Generating Processes and Activities a. Excavation will take place during the winter months, where the ground will either be frozen and or wet/muddy from the frost melt. Water conditioning the soil is not anticipated for the initial excavation. If the conditions present themselves where dust becomes excessive road and soil watering will commence. 8. Routine Maintenance Activities: a. Routine maintenance activities will seize once the construction activity begins. Lot 15 has been routinely been maintained by a landscape maintenance company as part of the green belt of Harmony Ridge. Routine maintenance is not going to be implemented until such time the site is fully stabilized and landscaped. 9. Off-Site Waste Management Practices: a. All waste produced from construction activities will be handled by Gallegos Sanitation. A 30 yard dumpster will be stored on the north side of lot 15, near the corner of Dusty Sage Drive and Prairie Ridge Drive. See Construction Waste Management Plan for further details. No construction waste materials will be buried, dumped, or discharge into any receiving waters. 10. Concrete Truck Washing: a. A metal concrete washout container will be located on the lot 13. The container will be enclosed in silt fence and regularly maintained. The container will be located more than 50ft from any storm water inlet on Dusty Sage Drive. 11. Dedicated Concrete and Asphalt Batch Plants a. No concrete or asphalt batch plant will be located on site. 12. Non-Industrial Waste Sources: a. Cleanup of any loose construction trash or debris will be addressed daily. The site and the surrounding area will be patrolled for waste and disposed of in the proper way as defined in the Construction Waste Management Plan. b. Portable sanitary sewage facilities will be placed within the silt fence area and not within 50ft of any storm water inlet. Any portable sanitary sewage facility will be anchored down to avoid any potential leakage and serviced weekly. 13. Potential Spills a. Spills and leaks will be immediately handled by a Tree Line Builders employee or subcontractor in accordance to the EPA’s Spill Control and Countermeasure Plan (SPCC). The SWMP administrator will be notified immediately of any spill or leak on site and respond the situation as best defined by the SPCC. 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 b. Weekly safety meetings will be conducted on site, material handling and spill prevention will be highlighted throughout these meetings in an effort to prevent and educate contractors on spill prevention and response. c. Potential spills risk will be mitigated by not storing containment materials on site regularly. 14. Final Stabilization: a. Final Stabilization will occur as soon as the construction schedule and weather allows so. Given the relatively small area that will need to be landscaped surrounding the finished 6 plex of townhomes sod will be installed. No seeding will be done on lot 15. b. Lot 13 where the spoils form the excavation will be stored temporary, will be graded once lot 15 is completely backfilled. Lot 13 will be graded to allow for positive drainage to the south in accordance to the existing conditions. At such point lot 15 will be seeded to allow for final stabilization and removal of the silt fence installed and any other remaining erosion control containment systems. 15. Best Management Practices: a. BMP’s for erosion and sediment control will be constantly evolving throughout construction to provide the best solutions to managing the ever changing erosion control conditions. This will be accomplished through a multi-phase excavation operation show in the figures below. As the dynamics of the construction site changes the BMP’s will follow such suite to provide the most effective management practices for erosion control. See Figures 3 and 4 for illustration of BMP’s. See phased BMP section below for further details. 16. Erosion Reduction and Control: a. Construction of the Harmony Ridge 6 plex will require 2 phases of excavation that require the removal of vegetation cover and topsoil increasing the flow of the volume of storm water runoff. Controlling this increased volume of storm water runoff will be accomplished through a combination of different erosion control methods listed below. 1. Multiphase excavation schedule to limit the area of disturbed soil 2. Minimum area of excavation and over dig to limit the area of disturbance 3. Diversion and control of runoff water leaving the site 4. Limit the run on water into the site 5. Temporary gravel driveways to minimize the area of disturbance 17. Sediment Reduction and Control a. Controlling the loose sediment leaving the site will be accomplished by a series of containment systems and methods. These containment systems are designed to mitigate the flow of sediments into the storm water system. Containment systems will change as the site changes to provide the best solutions to minimizing the impact of loose sediments leaving the site and entering the storm water system. The following containment systems will be implemented throughout construction and in till final stabilization is achieved. 1. Silt fence is the number one defense for loose sediment trying to leave the site 2. Straw bales will used on a as needed basis to help back up the silt fence and help as means of temporary stabilization 3. Wattles will be used to protect the breaks in the silt fence used as construction entrances into the site. 4. Inlet protection is the final barrier to prevent storm water pollution from sediment runoff that has made it past the silt fence and wattles. 5. Site fencing limits the traffic of vehicles within the site, thus limiting the tracking of sediments off site 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 6. Tracking pad prevents the tracking of sediment off site to vehicles that are necessary to be on the construction site b. Further details of how the sediment containment systems will be managed is listed below. Job Specific Construction Details of Erosion Control and Sediment Control Measures: The following site specific management practices are implemented to reduce and control erosion and loose sediment from leaving the site and polluting the storm water system.  Excavation will be done in two separate phases to limit the area of disturbance.  In order to minimize the area of disturbance, excavation will be limited to the minimum area of foundations and minimum over dig required.  Silt fence will be installed prior to any disturbance activities on site  Silt fence will be not only inspected by the City of Fort Collins erosion control inspector but by the SWMP administrator on a weekly basis.  Silt fence will be maintained on an as needed basis as deemed necessary by either the city official or the SWMP administrator.  Straw wattles will be used as a break in the continuous silt fence to allow for construction entrance and exit.  Wattles will be maintained and replaced as deemed necessary by either the city erosion control official or the SWMP administrator.  Inlet protection will be in the form of wattles installed just uphill of any storm water inlet in range of the site.  If the city official or the SWMP administrator deems the wattle insufficient for inlet protection at that point the switch would be made to inlet basket protection.  Temporary gravel driveways will be put in place to minimize the area of disturbance acting as a form of temporary stabilization until the final concrete driveways can be poured.  Lot 13 will house the soil stockpile generated from the spoils of lot 15’s excavation. Once lot 15 is backfilled and properly graded as per grading plan, lot 13 will be graded and seeded to achieve final stabilization. Phased BMP Implementation: As construction starts and progresses specific BMP phases will directly correlate with the construction schedule to mitigate any pollution into the storm water system. The phases are detailed below and each phase is illustrated in the figures listed below as well. Phase one of excavation will consist of approximately a 60’x180’ stretch of lot 15 averaging 9’ in depth to be excavated and hauled to lot 13. Prior to any construction activity erosion control containment systems will be installed and inspected on the site. See Figure 1 for site plan referencing the initial area of disturbance caused by phase one of excavation. During phase one of excavation the spoils generated from lot 15 will be hauled to lot 13 where once again erosion control containment systems will be previously installed prior to any construction activities. Loading of trucks hauling dirt down the street to lot 13 will be done in a way to minimize vehicle tracking of sediments off site. Rather than having trucks drive into the site a front loader will load trucks parked on Dusty Sage Drive. Silt fence will be installed tight to the sidewalk as shown in figure 3. The front loader will be able to extend the bucket out past the sidewalk and over the silt fence to load trucks on the street. Loading on street eliminates the need for trucks to come onto the site and track sediments off the site. 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Spoils generated from lot 15 phase one excavation hauled to lot 13 will be enclosed in silt fence. A straw wattle will provide the entrance for trucks to back up into the site to unload. A front loader will be stationed on lot 13 to pile and grade the spoils from lot 15 as there hauled. Other erosion containment systems used near lot 13 will include 2 wattles placed just uphill of the storm water inlet shown in figure 3. During phase one excavation special care will be noted for the condition of Dusty Sage Drive. With the loading and hauling from lot 15 to lot 13 a certain degree of loose sediment on the road is to be expected. Scraping down the roads with a front loader or a skid steer will be done daily during the phase one excavation. A street sweeper may be utilized if conditions present themselves or if noted by the SWMP administrator or the city erosion control official. Phase two of excavation will involve similar BMP’s to that of phase one. Phase two will consist of approximately a 25’x180’ by roughly 4’ deep excavation. Phasing the excavation into two separate operations minimizes the area of disturbance. Once again Dusty Sage Drive will be scraped daily as loading and hauling activities are expected to leave a certain degree of loose sediment. Phase three will consist of the backfilling of both the foundations and garages on lot 15 from the soil stockpile located on lot 13. Once again during this loading and hauling process special care will be noted for the condition of Dusty Sage Drive as deemed necessary by either the SWMP administrator or the city erosion official. Once backfilling of lot 15 is complete the remaining soil left stockpiled on lot 13 will be graded to allow positive drainage on lot 13. There is roughly 5 feet of elevation change existing on lot 13 that will allow the lot to accept quite a bit of dirt and still allow positive drainage. If the spoils left over are too much for the lot to accept we will haul the remaining spoils off site. Once backfilling and grading actives are complete on both lot 15 and lot 13, lot 13 will be the focus to stabilize as soon as possible. Weather permitting lot 13 will be seeded to achieve stabilization. Silt fence along with inlet wattle protection will stay in place in till such time that lot 13 is deemed stable by the city erosion control official. Once phase three of backfilling and grading actives is complete, construction will be ready to go vertical on lot 15. At this point once all major grading and excavation activities are substantially complete the erosion containment systems will be reevaluated to better suit the changing construction site. Silt fence will be maintained and replaced as needed after all heavy equipment and dirt moving activities are complete. Wattles will be replaced as deemed necessary by the SWMP administrator or the city erosion official. Inlet protection wattles will also be evaluated at this point to determine if they need to be replaced. After phase three grading and backfilling activities are complete, gravel road base will be trucked in to provide temporary driveways and help stabilize the entrance to the site. Road base will drastically help with the trekking of sediments off site and will allow for vehicles to enter the site. Once the road base and grading activities are complete phase four of erosion control plan will be implemented. Phase four of erosion control will stay in place through the rest of construction and until final stabilization is achieved. Temporary road base driveways will stay in place until the all the final concrete flatwork is poured including the new concrete driveways. Given the relatively small area left to stabilize on site 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 sod will be installed rather than seeding. At such point the landscaping is fully installed and the site is deemed stable by the erosion control official, any and all remaining erosion control containment systems will be removed permanently. Final Stabilization: According to storm water regulations, “final stabilization means that all ground surface disturbing activities at the site have been completed and all disturbed areas have been either built on, paved, or a uniform vegetative cover has been established with an induvial plant and a density of at least 70% of pre- disturbance levels, and the vegetation cover is capable of providing erosion control equivalent to pre-existing conditions, or equivalent permanent, physical erosion reduction methods have been employed.” When the site reaches final stabilization as deemed by the city erosion control official all temporary erosion containment systems will be removed. 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Figure 1 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Figure 2 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Figure 3 Figure 4 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Figure 5 Figure 6 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Erosion Control Drawing 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127 Grading Plan 4608 Dusty Sage 141 S College Ave, Suite 103 Fort Collins, CO 80524 970 493 9127