Loading...
HomeMy WebLinkAboutSite Certifications - 10/30/2017 FORT COLLINS: 301 North Howes Street, Suite 100, 80521 | 970.221.4158 GREELEY: 820 8 th Street, 80631 | 970.395.9880 | W EB: www.northernengineering.com October 27, 2017 Mrs. Heather McDowell City of Fort Collins Stormwater Utility 700 Wood Street Fort Collins, Colorado 80522 RE: Drainage Certification for Lyric Cinema Fort Collins, Colorado Dear Heather: This drainage certification letter is provided to verify as-constructed conditions for Lyric Cinema. Landmark, Ltd. completed survey work October 13, 2017, and Northern Engineering visited the site October 17, 2017, to verify general compliance with the Final Utility Plans for Lyric Cinema, dated 11/23/2016 by Northern Engineering. Included in this drainage certification submittal are the following: Attachment 1 - City of Fort Collins Overall Site and Drainage Certification Form. Attachment 2 - City of Fort Collins During Construction Inspection Checklist and photographs provided by contractor. Attachment 3 - As-constructed detention pond calculations. Attachment 4 - As-constructed record drawings for Grading and Storm Drain Plan and Profile Sheets. Based on the calculations shown in Attachment 3, the as-built water quality pond volumes are in Table 1. Table 1: Water Quality & Detention Pond Volumes Pond Design Water Quality Vol. (ft3) As-built Water Quality Vol. (ft3) Design Detention Vol. (ft3) Design Max. Attenuation w/ Offsite Flow (ft3) As-built Detention Vol. (ft3) Water Quality & Detention Pond 1,616 1,675 16,555 29,602 30,150 We have concluded, based on the attached information and personal site inspection, that the drainage features for the project site have been constructed in substantial compliance with the above referenced Final Utility Plans, with the following exceptions: FORT COLLINS: 301 North Howes Street, Suite 100, 80521 | 970.221.4158 GREELEY: 820 8 th Street, 80631 | 970.395.9880 | W EB: www.northernengineering.com • Item I.A.5: Based on permeability tests of the pre-developed soil conditions within the LID portion of the pond, there exists a 5 to 7 ½ feet of sandy clay and clayey sand overlaying cleaner sand and gravel (CTL Thompson, July 29, 2016). The sandy clay and clayey sand has a permeability of 0.38 ft/day (Test Pit P-4). This low permeability was assumed for the entire area of the LID portion of the pond (37,56 ft2), and the resulting infiltration is 0.02 cfs. Based on conversations with the contractor, the two dry wells within the LID feature were installed deep into the cleaner sand and gravel with good infiltration. According to the permeability tests performed by CTL Thompson, the cleaner sand and gravel has a permeability of 10 ft/day (Test Pit P- 1). This higher permeability was assumed for both dry wells, and the resulting infiltration is 0.02 cfs. The orifice rating curve from the Final Drainage and Erosion Control Report for Lyric Cinema was adjusted by adding 0.04 cfs throughout the curve. This revised rating curve (see Table 2) was then entered in the State Drain Time Spreadsheet provided by the City of Fort Collins to determine the drain time for the detention pond. This results in 97% of the inflow volume will drain in 20 hours and 99% of the inflow volume will drain in 62 hours. • Item I.B.4: The 100-year control orifice was installed per the approved design drawings. • Item III.A.1: The 21 feet of the Storm Sewer A from Manhole A1 to Manhole A2, located within the right-of-way, (shown on Sheet C403) was changed to a 19” x 30” elliptical pipe (24” equivalent) to avoid the gas main in College Avenue. • Item III.A.2: Storm Sewer A from Manhole A1 to Manhole A2 (shown on Sheet C403) was constructed with a slope below the design of 0.25% (a slope of 0.23% was constructed). We have re-analyzed this storm line and compared the hydraulic grade line. As shown below, there is no minimal change to the 100-year HGL. Base on the revised HGL, we feel this will convey the design storm hydraulic capacity. Table 2: Revised Outfall Rating Curve User Defined User Defined Stage [ft] Discharge [cfs] 0.00 0.04 0.28 0.04 0.53 0.04 0.78 0.06 1.03 0.07 1.28 0.07 1.53 0.07 1.78 0.08 2.03 0.08 2.28 0.08 2.53 0.08 2.78 0.09 3.03 0.09 3.28 0.09 3.50 0.09 FORT COLLINS: 301 North Howes Street, Suite 100, 80521 | 970.221.4158 GREELEY: 820 8 th Street, 80631 | 970.395.9880 | W EB: www.northernengineering.com • Item III.A.2: Storm Sewer C from Inlet C2 to Inlet C3 (shown on Sheet C405) was constructed with a slope below the design of 0.40% (a slope of 0.28% was constructed). We have re-analyzed this storm line and compared the hydraulic grade line. As shown below, there is no minimal change to the 100-year HGL. Base on the revised HGL, we feel this will convey the design storm hydraulic capacity. FORT COLLINS: 301 North Howes Street, Suite 100, 80521 | 970.221.4158 GREELEY: 820 8 th Street, 80631 | 970.395.9880 | W EB: www.northernengineering.com • Item III.B.2: Northern Engineering did not observe construction of the storm sewer. Northern Engineering was unable to verify the encasements and clearances specified on the approved construction plans. • Item III.B.3: Northern Engineering did not observe construction of the storm sewer. Northern Engineering was unable to verify the specific joint types and construction methods. • Item VII.A.2: According to the contractor, the subdrain under the LID was installed per the approved design drawings. Northern Engineering did not observe construction, and Northern Engineering was unable to verify if the perforated and non-perforated sections of the underdrain were constructed per the approved design drawings. • Item XIII.A.1: Construction debris was not removed at the time of Northern Engineering’s site inspection. • Item XIII.A.2: Ruts were not removed at the time of Northern Engineering’s site inspection. The owner was in the process of removing ruts and installing landscaping at the time of Northern Engineering’s site inspection. Please feel free to contact me with any questions you may have. Thank you, NORTHERN ENGINEERING SERVICES, INC. Frederick S. Wegert, PE Project Engineer 12/15 Page 1 OVERALL SITE and DRAINAGE CERTIFICATION Commercial, Multi-Family and Subdivision Certification Form and Checklist Project Name: Date: Building Permit Numbers: (Commercial or multi-family) Per the requirement in Fort Collins Stormwater Criteria Manual (FCSCM) Volume 1, Section 6.11, please fill in all applicable items in this Certification Form for Commercial, Multi-Family and Overall Single Family sites. NOTE: several items must be verified during construction. A copy of the approved grading plan must be submitted with the as-built grading plan. (As-built elevations must be written in red next to the approved elevations.) •Use “Yes” for items completed as described. •Use “N/A” for items that are not applicable to the site being certified. •If any blanks are “No,” attach an explanation referencing the item number below. Attach an explanation or description of the as-built condition for any items listed or for anything not listed but shown on the approved construction plans. Provide an as-built redline or Mylar drawing with the following: I.Water Quality and Quantity Detention Basin Certification - FCSCM Vol.2, Ch.10 For multiple detention basins on a site, provide the following for each basin separately: A. Volume: As-built topographic verification is attached at 1-foot (or less) contour intervals and volume verification calculations for the water quality capture volume and the 100-year detention storage volume. 1. Detention basin topography was prepared by a professional land surveyor registered in the state of Colorado. 2.Both proposed and as-built contours are shown on the same plan sheet (dashed lines for proposed and solid lines for as-built). 3.All critical spot elevations as shown on the approved construction plans have been verified and the as-built elevations are shown on the plan sheet. 4.Stage-storage-discharge tables are provided on a separate document. 5.Verification that designed drain time is in compliance with Colorado Revised Statute § 37-92- 602(8) is attached and has been uploaded to the Statewide Compliance Portal (tinyurl.com/COCompliancePortal) for approval. Uploaded documents must include: a.The cover sheet from the approved drainage report b.The stamped certification page from the approved drainage report c.As-built topographic survey d.Stamped certification page from the Overall Site & Drainage Certification e.PDF output from the Stormwater Detention and Infiltration Design Data Speadsheet 12/15 Page 2 B.Water Quality and Quantity Detention Basin Grading: Attached is as-built verification that there is a minimum 2% positive fall into the concrete trickle pans or flow-line(s) from all areas in the bottom of the detention pond. If there is a “soft pan” in the flow-line, all areas still must meet the minimum 2% grade requirement. 1.Low Flow: Choose one of the following detention basin low flow options as applicable: a. Turf swale for low flow path in detention basin. There is a minimum 2% grade in the flow-line(s) of the detention basin. The flattest as-built grade is . b.Concrete pan for low flow in detention basin. There is a concrete pan installed that meets the grades as shown on the approved construction plans. (Show as-built spot elevations.) c.Soft pan for low flow in detention basin. •Verify and document the soft pan material gradation, trench width and depth - to be verified during construction by engineer. Picture documentation is preferred or engineer’s statement of visual inspection and compliance. (Choose one below.) o There is a soft pan with an underdrain installed that meets the design on the approved construction plans. (Show the underdrain grades, bedding material, geotextile, spot elevations, bends, cleanouts, etc.) o There is soft pan installed without an underdrain but there is a type A or B soil. The soil type must be documented by supplying verification from a registered professional geotechnical engineer. NOTE: Spot elevations are to be within 0.2 ft. +/-. 2. Side Slopes: The as-built side slopes of the detention basin have been calculated and are shown. Indicate the side slope with an arrow and a numerical value (e.g., 6.25:1). The maximum slope allowed is 4:1. Small areas of 3:1 may be acceptable, but slopes steeper than 3:1 must be stabilized or re- graded. Provide documentation if a variance was granted for steeper slopes during the design process. 3.Spillway Certification: The following items must be field verified: a.The location of the spillway is indicated on the as-built plan. b.The width of the spillway is indicated on the as-built plan. c.The elevation(s) of the spillway is shown on the as-built plan. d.A concrete ribbon defines the location and grade of the spillway. e.There is downstream scour protection in the spillway as per the construction plans. Indicate type: (riprap size “D50” gradation and bedding type, geotextile, buried riprap with inches of bury, etc.). f.There are no obstructions in the spillway, such as trees, bushes, sidewalks, landscape features, rocks, etc. 12/15 Page 3 4.Outlet Structure Certification a.The orifice plate for the approved release rate is installed with the correct size and location of the orifice. b.The orifice plate for the water quality outlet is installed with the correct hole size, number of rows and columns of holes. c.The bottom hole on both the water quality and quantity outlets are at the bottom of the plate so no water ponds in front of the plate. d.The well screen is the correct material and is installed as shown on the construction plans. e.100-year overflow grate elevation is . (Elev. A on detail D-46) f.The top elevation of the water quality capture volume is . (Elev. B on detail D-46) g.Overflow grate is made of the correct material, has the correct bar spacing, is hinged at the top and bolted at the bottom. h.The bottom of the outlet box has no obstructions or misalignments that will cause it to retain runoff water and is sloped at 2% towards outlet. II.Channels/Swales - FCSCM Vol.1, Ch.7, Sect.3&4 A. Capacity: The as-built capacity of all the major channels and swales has been verified. They meet or exceed capacity requirements shown in the approved drainage study for this project. 1.All swales are located within the drainage easements as shown on the construction plans. 2.Longitudinal slopes and side-slopes (cross-sections) have been verified. Design criteria requires longitudinal slopes of 2% min. (on vegetated swales) and side-slopes no steeper than 4:1. If these criteria are not met, the certification engineer will write a justification and propose mitigation for each instance or have the issues corrected. If variances to these criteria have previously been approved and are shown on the construction plans, no justification is needed. 3.As-built spot elevations on channels/swales are shown that correspond to spot elevations shown on the approved construction plans. 4.All permanent erosion control measures are installed as shown on the approved construction plans (e.g., drop structures, riprap, TRMs, etc.). (Include pictures and verification of the materials used as part of this verification.) 5.All pans, curbs, storm pipes or other appurtenances appropriately tie into each other in the system. (Pictures at tie-in points suggested.) 6.The minimum freeboard is provided for all channels and swales as shown on the approved construction plans or as identified in the approved drainage study. (Show the freeboard provided on the cross-sections as on the construction plan set or attached as separate documentation.) 7.The low flow portion of all channels or swales is clear of obstructions. (No landscaping, trees, shrubs, sod, etc. infringe on the low flow portion of channels or swales.) 12/15 Page 4 III.Storm Pipes (aka storm drains) - FCSCM Vol.1, Ch.6, Sec. 4 A. Storm Drain Pipe Capacity: The as-built capacity of all pipes installed on this project has been verified and meets or exceeds the capacity requirements shown in the approved drainage study for this project. 1.All storm drain pipe sizes and materials have been verified and are in conformance with the approved construction plans. (Indicate on the plan and profile sheets that they have been verified.) Material and size substitutions must be approved prior to installation. If a pipe size or material was changed during construction, the certification engineer must attach the approval documents or supply them with this certification. Approval documents must include a calculation documenting the capacity equivalency (equal or greater) of the substituted size. 2.The longitudinal slope of the pipe is as shown on the approved construction plans. The acceptable minimum slope is 0.4%. All slopes flatter than the designed slope on the construction plans must be justified with capacity calculations on an attached sheet. 3.The as-built invert elevations have been verified and are shown on the plan and profile sheets of the approved construction plans. B.Storm Drain Pipe Installation Requirements: All pipes are installed in accordance with the approved construction plans. 1.The minimum cover requirements for all pipes have been met as shown on the approved construction plans. These will be called out in critical locations. 2.All encasements and clearances as specified on the approved construction plans have been met. 3.Any specific joint types or construction methods specified on the approved construction plans have been met. (List on a separate sheet and attach to this certification.) IV.Concrete Pans - FCSCM Vol.1, Ch.7, Sec.4.1.3.4 A. Construction/Installation: All concrete pans have been constructed in accordance with the approved construction plans. 1.The concrete pans are the correct size/width as shown on the approved construction plans. 2.The longitudinal slopes of the pans are as shown on the approved construction plans. The certification engineer must justify or mitigate longitudinal slopes less than the minimum of 0.4% unless a flatter slope was approved and is shown on the approved construction plans. Provide mitigation or justification by separate document. 3.The cross-section of the pan is as shown on the construction plans. (Specifically, the pan cross- section is “V” shaped and meets the side slope shown on the detail.) 4.The concrete pans are a minimum of 6 inches thick without reinforcement and a minimum of 4 inches thick with a minimum of 6X6-W14xW14 reinforcement per detail D20B and D20C. (Provide documentation of the reinforcement used if different than shown on the details or on the approved construction plans.) 5.The spot elevations shown on the concrete pan(s) have been verified and are shown on the as- built drawings. 12/15 Page 5 V. Storm Drain Inlets - FCSCM Vol.1, Ch.6, Sec. 3 A. Construction/Installation: All storm drain inlets have been constructed in accordance with the approved construction plans. 1.The size and type of inlets are consistent with the inlets shown on the approved construction plan. Indicate by writing “Verified” on each inlet on the plan sheet or list on a separate document the inlet number(s), type and size (length). If the inlet installed is other than the one on the approved construction plan detail sheet, provide the name and source of the detail with justification for equal or better capacity. 2.The size of the inlet opening is consistent with the approved detail. (Check height and width.) 3.The elevation of the grate (if applicable) is at the elevation shown on the street profile or as indicated by a spot elevation on the construction plans. 4.The as-built invert elevations of all pipes entering and leaving the inlet are shown on the plan and profile sheets within construction tolerance of 0.2 feet. If substantially different, provide justification and capacity calculations to show the capacity is not affected or propose mitigation. 5.The as-built size of the inlet box is as shown on the construction plans or an explanation or justification is attached. 6.All inlet covers are stenciled or stamped with the following designation: NO DUMPING – DRAINS TO POUDRE RIVER. VI.Culverts - FCSCM Vol.2, Ch.9 A. Construction/Installation: All culverts have been constructed and/or installed in accordance with the approved construction plans. 1.All culvert sizes have been verified as indicated on the as-built construction plans as correct. 2.The culvert material type for all culverts installed is as on the approved construction plans and is indicated on the as-built plans. 3.The as-built invert “in and out” elevations have been verified and are indicated on the as-built construction plans. 4.The culvert headwalls or wing walls have been installed as shown on the approved construction plans. Headwalls or wing walls may be needed in the as-built conditions onsite if the slopes adjacent to the culvert are greater than 4:1. Please note areas needing stabilization in the certification narrative. An alternative to consider is a turf reinforcement mat (TRM). VII.Sub-Drains A. Construction/Installation: All sub-drains shown on the construction plans have been installed in accordance with those plans. Sub-drains installed with the sanitary sewer are to be verified on the sanitary sewer plan and profile sheets of the construction plans. (NOTE: Indicate any sub-drains installed after the plans were approved on the as-built plans.) 1.The size of the sub-drains are as approved on the construction plans and are indicated on the as- built plans. 2.The type of sub-drain, in particular the perforated and non-perforated sections of the drain, are as indicated on the approved construction plans. 12/15 Page 6 3.The cover requirements per the construction plans are provided. 4.The cleanouts have been installed at the locations shown on the construction plans and are accessible for cleaning. (Cleanouts can be buried a maximum of 6 inches deep with their locations marked.) 5.The backfill materials for sub-drains are as shown on the approved construction plans. (This includes the type, depth and width.) 6.The geo-textile liner completely wraps the sub-drain and the permeable backfill material unless shown otherwise on the approved construction plans. (Sub-drain pipe wrapped in a sock filter material is accepted only if approved prior to installation.) VIII.Curb Cuts A. Construction: All curb cut openings are constructed in accordance with the approved construction plans. 1.The size (width) of the curb cut opening is as shown on the approved construction plans. 2.The curb cut openings tie into a downstream swale, pipe, or other appurtenances with a smooth transition and there no obstructions such as riprap or sod impeding the flow downstream of the curb cut. IX.Sidewalk Culverts & Chases A. Construction/Installation: All sidewalk culverts have been installed at the locations shown on the approved construction plans. 1.The size (width and length) of the culverts are as shown on the approved construction plans. 2.The cover plate is a minimum 5/8-inch galvanized plate bolted to a galvanized angle iron per the detail shown on the approved construction plans or per the City’s detail. 3.The sidewalk culvert invert “in and out” elevations have been verified and are indicated on the as-built plans. 4.The sidewalk culvert opening is as shown on the approved construction plans or per the City’s detail. 5.There is a smooth transition both on the inlet and outlet ends of the sidewalk culvert with no obstructions such as riprap or sod impeding the flow into or out of the sidewalk culvert. X. Site Grading A. Construction: All common open spaces have been graded in accordance with the approved construction plans. 1.The grading on all common open spaces bordering private lots has been verified as correct and the as-built rear lot corner elevations have been shown on the as-built plans. 12/15 Page 7 2.The as-built contours for “overlot grading” are shown on the as-built construction plans for all common open spaces, tracts, outlots, etc. If not in compliance, please attach a narrative describing the situation for noncompliance and when it may be corrected. An escrow for overlot grading may be required. (NOTE: Residential Lot Grading Certification is a separate process from this Overall Site Certification. It is understood that residential lots will be brought to final grade once the foundation is backfilled so they may be lower than the plan shows at this Overall Site Certification stage.) 3.All turf reinforcement mats (TRMs) have been installed as shown on the approved construction plans and the slopes are stabilized. XI.Riprap - FCSCM Vol.1, Ch.7, Sec.4.4.4.3 A. Construction: All riprap has been installed in the locations and sizes indicated on the approved construction plans. XII.Permanent Erosion Control Fabric - FCSCM Vol.1, Ch.7 A. Construction: All fabric has been installed in the locations and sizes indicated on the approved construction plans. 1.All fabric was installed per the details on the approved construction plans. XIII.Post-Construction Site Cleanup - FCSCM Vol.3, Ch.7 A. Construction: All construction debris and obstructions of any kind have been removed from drainage paths. 1.All construction debris has been removed except in staging area(s). 2.All ruts have been smoothed out in all construction areas. 3.All areas needing reseeding have been identified and future stabilization goals have been coordinated with the Erosion Control Inspector and in accordance with FCSCM Vol.2 Chapter 12. Note the area needing stabilization in the narrative. XIV.Certification of Other Permanent BMPs - FCSCM Vol.2, Ch.8, Sec.2 & FCSCM Vol.2, Ch.12 A.The construction of channel drop structures is in accordance with the approved plan both in location, horizontal dimensions and cross-section. XV.Certification of LID and Water Quality Facilities - FCSCM Vol.3, Ch.4 A.Attached are the During Construction Inspection Checklist for Low Impact Development (LID) and other items to be verified during construction, along with pictures and other required documentation. Stormwater Facility Name: Facility Location & Jurisdiction: User (Input) Watershed Characteristics User Defined User Defined User Defined User Defined Watershed Slope =0.010 ft/ft Stage [ft]Area [ft^2]Stage [ft]Discharge [cfs] Watershed Length-to-Width Ratio =2.00 L:W 0.00 199 0.00 0.04 Watershed Area =1.59 acres 0.25 1,165 0.28 0.04 Watershed Imperviousness =44.4%percent 0.50 2,405 0.53 0.04 Percentage Hydrologic Soil Group A =0.0%percent 0.75 3,229 0.78 0.06 Percentage Hydrologic Soil Group B =0.0%percent 1.00 3,744 1.03 0.07 Percentage Hydrologic Soil Groups C/D =100.0%percent 1.25 4,056 1.28 0.07 1.50 4,300 1.53 0.07 1.75 4,797 1.78 0.08 2.00 5,573 2.03 0.08 2.25 6,358 2.28 0.08 User Input: Detention Basin Characteristics 2.50 7,037 2.53 0.08 WQCV Design Drain Time =40.00 hours 2.75 7,647 2.78 0.09 3.00 8,289 3.03 0.09 3.25 9,072 3.28 0.09 3.50 9,900 3.50 0.09 After completing and printing this worksheet to a pdf, go to: https://maperture.digitaldataservices.com/gvh/?viewer=cswdif, create a new stormwater facility, and attach the pdf of this worksheet to that record. Routed Hydrograph Results Design Storm Return Period =WQCV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year Two-Hour Rainfall Depth =0.53 0.98 1.36 1.71 2.31 2.91 3.67 in Calculated Runoff Volume =0.025 0.054 0.097 0.139 0.218 0.289 0.390 acre-ft OPTIONAL Override Runoff Volume =acre-ft Inflow Hydrograph Volume =0.025 0.053 0.097 0.138 0.217 0.289 0.390 acre-ft Time to Drain 97% of Inflow Volume =7 13 20 26 37 47 59 hours Time to Drain 99% of Inflow Volume =8 13 20 27 38 49 62 hours Maximum Ponding Depth =0.58 0.93 1.39 1.78 2.36 2.79 3.30 ft Maximum Ponded Area =0.061 0.082 0.096 0.112 0.153 0.178 0.212 acres Maximum Volume Stored =0.019 0.044 0.085 0.125 0.203 0.274 0.373 acre-ft Workbook Protected Worksheet Protected Stormwater Detention and Infiltration Design Data Sheet Lyric Cinema Pond 1 Fort Collins, Colorado Asbuilt Lyric Pond SDI CRS Spdsht 2017.10.25.xlsm, Design Data 10/30/2017, 11:54 AM Doing_Clear_Formatting =Yes CountA=1 0 1 2 3 #N/A #N/A 0 1 2 3 #N/A #N/A Check Data Set 1 Check Data Set 1 Area Discharge Stormwater Detention and Infiltration Design Data Sheet 0 1 2 3 4 5 6 7 8 9 0.1 1 10 FL O W [ c f s ] TIME [hr] 100YR IN 100YR OUT 50YR IN 50YR OUT 25YR IN 25YR OUT 10YR IN 10YR OUT 5YR IN 5YR OUT 2YR IN 2YR OUT WQCV IN WQCV OUT 0 0.5 1 1.5 2 2.5 3 3.5 0.1 1 10 100 PO N D I N G D E P T H [ f t ] DRAIN TIME [hr] 100YR 50YR 25YR 10YR 5YR 2YR WQCV Asbuilt Lyric Pond SDI CRS Spdsht 2017.10.25.xlsm, Design Data 10/30/2017, 11:54 AM Project: Date: 4972.1 1,616.0 ft3 4974.7 1,674.7 ft3 Crest of Pond Elev.:4975.95 29,602.4 ft3 4975.76 Maximum Elevation Minimum Elevation cu. ft.acre ft cu. ft.acre ft 4971.20 N/A 0.0 0 0.0 0.00 0.0 0.00 4971.25 4971.20 198.6 0.05 5.0 0.00 5.0 0.00 4971.50 4971.25 1,165.1 0.25 170.5 0.00 175.4 0.00 4971.75 4971.50 2,405.4 0.25 446.3 0.01 621.7 0.01 4972.00 4971.75 3,229.2 0.25 704.3 0.02 1,326.1 0.03 4972.25 4972.00 3,743.7 0.25 871.6 0.02 2,197.7 0.05 4972.50 4972.25 4,056.5 0.25 975.0 0.02 3,172.7 0.07 4972.75 4972.50 4,299.6 0.25 1,044.5 0.02 4,217.2 0.10 4973.00 4972.75 4,796.6 0.25 1,137.0 0.03 5,354.2 0.12 4973.25 4973.00 5,573.3 0.25 1,296.2 0.03 6,650.5 0.15 4973.50 4973.25 6,357.7 0.25 1,491.4 0.03 8,141.8 0.19 4973.75 4973.50 7,037.3 0.25 1,674.4 0.04 9,816.2 0.23 4974.00 4973.75 7,647.1 0.25 1,835.5 0.04 11,651.8 0.27 4974.25 4974.00 8,288.6 0.25 1,992.0 0.05 13,643.7 0.31 4974.50 4974.25 9,072.2 0.25 2,170.1 0.05 15,813.8 0.36 4974.75 4974.50 9,899.7 0.25 2,371.5 0.05 18,185.3 0.42 4975.00 4974.75 10,631.5 0.25 2,566.4 0.06 20,751.7 0.48 4975.25 4975.00 11,364.7 0.25 2,749.5 0.06 23,501.2 0.54 4975.50 4975.25 12,015.6 0.25 2,922.5 0.07 26,423.8 0.61 4975.80 4975.50 12,823.8 0.30 3,725.9 0.09 30,149.7 0.69 North Rain Garden Stage Storage Curve Contour Contour Surface Area (ft2) Depth Incremental Volume Cummalitive Volume Existing Pond Stage Storage Curve 1089-001 Fort Collins, Colorado F. Wegert Detention Pond Elev at Design Volume: Lyric Cinema 10/17/2017 Pond Outlet and Volume Data 100-Year Design Volume: Volume at WQ Outlet: Project Number: Project Location: Calculations By: Pond No.: Water Quality Design Vol.:WQ Outlet Elev.: Grate Elev. (100-Yr): 10/17/2017 8:18 AM D:\Projects\1089-001\Drainage\Detention\ 1089-001_Asbuilt_Stage-Storage_2017.10.13.xlsx\Pond 400 North Link Lane | Fort Collins, Colorado 80524 Telephone: 970-206-9455 Fax: 970-206-9441 July 29, 2016 UR Design 252 Linden Street Studio 7 Fort Collins, Colorado 80524 Attention: Brian A. Majeski Subject: Permeability Testing Proposed Lyric Cinema 1209 North College Avenue Fort Collins, Colorado CTL|T Project Number: FC06790-112 CTL|Thompson, Inc. has conducted soil permeability testing at the proposed Lyric Cinema location. The purpose of our investigation was to determine the hydraulic conductivity of two different soil types identified in our Soils and Foundation Investigation (Project No. FC06790-125, report dated January 26, 2015). This letter presents the results of our testing. Borings conducted during our Soils and Foundation Investigation encountered approximately 5 to 7½ feet of sandy clay and clayey sand overlying cleaner sand and gravel. For our permeability testing, six new borings were drilled using 4-inch solid stem auger and a truck-mounted drill rig. Three of the borings were advanced approximately 1 to 3½ feet to bottom into the sandy clay layer, and three of the borings were advanced to approximately 5½ to 6 feet to bottom into the sand and gravel layer. The borings were fitted with slotted PVC pipe to facilitate testing. Approximate locations of the borings are shown on Figure 1. Open hole, falling head permeability testing was conducted by adding approximately 1 to 3 feet of water to each hole and measuring the change in water depth over consecutive time intervals. A summary of our test results is provided in Table A.