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HomeMy WebLinkAboutSite Certifications - 07/29/2024Page 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) Chapter 3, Section 3.0 to certify as- built construction to the approved drainage and grading plans, 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 - FCSCM Ch. 6 and 7 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 11/19 Mulberry Connection 12-15-2022 B2104283; B2104286 Yes Yes Yes Yes Yes Yes Grading/Stormwater Certification Accepted (Certificate of Occupancy Released) Accepted by: Date: ☐ Escrow was held for CO and is now released we SW-WWW - Matt Simpson 07/29/2024 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: 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. 11/19 Yes N/A 0.5% Yes N/A N/A N/A Yes Yes Yes Yes No No Yes All spot elevations relatively met. Note: trickle channel in pond is less then 2%. Owner accepts the trickle channel as is. Page 3 4.Outlet Structure: 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 Ch. 8, Sec. 2.0 and Ch. 9, Sec. 5.0 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.) 11/19 Yes N/A N/A Yes Yes 4951.02 Yes 4952 Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Page 4 III.Storm Pipes (aka storm drains) - FCSCM Ch. 9, Sec. 4.0 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 and construction specifications. 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 Ch. 8, Sec. 2.0 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. 11/19 Yes Yes Yes Yes Yes Yes N/A N/A Yes Yes Yes Yes Yes Yes Page 5 V. Storm Drain Inlets - FCSCM Ch. 9, Sec. 3.0 A. Construction/Installation: All storm drain inlets have been constructed in accordance with the approved construction plans and construction specifications. 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 Type C, R, 13 and 16 inlet covers are stenciled or stamped with the following designation (or an equivalent): NO DUMPING – DRAINS TO POUDRE RIVER. VI.Culverts - FCSCM Ch. 9, Sec. 4.0 A. Construction/Installation: All culverts have been constructed and/or installed in accordance with the approved construction plans and construction specifications. 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 and the construction specifications. 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. 11/19 Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes No Yes Not on plans. Sub Drains are not on the as-built plans, but were installed per plan. Refer to photos. 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 and construction specifications. 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 - FCSCM Ch. 8 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. 11/19 Yes Yes Yes Yes N/A N/A N/A N/A N/A N/A N/A N/A N/A Yes Yes 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.Permanent Erosion Control BMPs - FCSCM Ch. 9, Sec. 7.0 A. Construction: All permanent erosion control BMPs have been installed per the approved construction plans. 1.All riprap has been installed in the locations and sizes indicated on the approved construction plans. 2.All fabric has been installed in the locations and sizes indicated on the approved construction plans. a.All fabric was installed per the details on the approved construction plans. XII.Post-Construction Site Cleanup - FCSCM Ch. 3, Sec. 2.0 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. XIII.Certification of LID and Water Quality Facilities - FCSCM Ch. 7 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. B.Attached is verification of the rain garden and/or sand filter flat surface area(s) and ponding volume(s). This verification includes survey of critical elevations. C.Attached is verification of the underground infiltration required volume(s), weir elevations, orifices, inspection ports and filtering fabric. This verification includes survey of critical elevations. D.All visible LID design features were verified as part of the engineer's site visit. 11/19 N/A Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes 11/19 Page 8 XIV.Certification of Other Permanent BMPs A.The construction of other permanent BMPs not specifically addressed in this certification is in accordance with the approved plan. This may include grade control structures, rundowns, bridges, stream access/improvements, etc. Please specify other permanent BMPs included on this site: XV. Certification and Erosion Control Measures - FCSCM Ch. 3 A. All temporary erosion control measures shall be removed upon stabilization. If at the time of preparing this certification there are any erosion control measures still remaining on the site, please note them in the narrative and verify that they need to remain at this time. If in doubt as to the need for any control measure, please consult with the Erosion Control Inspector at erosion@fcgov.com. XVI.Statement of Compliance - FCSCM Ch. 3 A. This certification is signed and stamped. By signing this form, the engineer(s) attests that he/she has visited and observed the site, and to the best of his/her knowledge, the as-built conditions of the drainage facilities are as described in the above form and in the enclosed as-built plans. B.Failure to properly disclose all known information could result in the rejection of this certification and prevent the release of any and all Stormwater Utility permit holds on Building Permits and/or Certificates of Occupancy within this development. XVII. Signature and Stamp by a Colorado-Registered Professional Engineer Engineer’s contact information: Name: Email: Phone: Company: Address: PE Stamp Rain Garden A, C, & underground stormtech chambers Yes Shane Cassidy SCassidy@ComunaleProperties.com 609-501-3500 Comunale Properties 1855 S Pearl Street, Suite 20 Denver, CO 80210 5/2 / 2 0 2 3 Mulberry Connection Site Drainage Certification Comments 1-18-23: Comunale Comment Response 4-28-23 Revised based on onsite meeting on 5/1/23 1. Consolidate all of the supporting PDFs into 1 PDF file. The site certification form should be at the front of the document. a. PDFs have been consolidated into one file. 2. Provide documentation showing the depth of installation for the dry well as shown in the design picture below. a. Unfortunately, no documentation on the drywell depth was recorded during construction. Photos of the installation are provided in the “Pictures of Dry well and Rain Gardens” PDF, that will be sent as part of the site certification. Note, drywell was tested and infiltrates water at a faster rate than designed. 3. Provide documentation showing the constructed volume and elevations for the underground stormtech water quality chambers. a. Unfortunately, no documentation of the depth of the stormtech system was recorded during construction. On 4/24, a measurement was taken of the depth of the stormtech at the north and south manholes. Depth was found to be 9’-4” (112”) on the north end and 9’-6” (114”) on the south end. VERIFY DESIGN DEPTH. b. Depth was verified onsite utilizing the installed viewports. Depth was confirmed to be 6’-7” 4. Provide documentation showing the underground stormtech water quality chambers are clean of sediment and debris from construction. (Suggest scheduling a site visit and we can observe together). a. Documentation is difficult to provide with a visual inspection, as there is approximately 6” of standing water. Let’s discuss during the site walk on Monday, May 1 st at 2:00 PM. b. Stormtech chambers were observed to be clean on 5/1/23 utilizing the installed view ports. 5. Please verify and confirm that the detention outlet orifice plate(s) matches the design (see images below). A picture of the installed configuration may help. Design: As-Built – from “Mulberry Connection – As-Built Pond.pdf” a. Refer to photos below for verification, all dimensions of the installed outlet plates are per the approved plans. 6. Provide survey documentation of the ‘lowest overtopping elevation’ at the south end of the “loading dock detention pond” near the south end of the middle drive aisle . This is a secondary overtop location for the detention ponds. Confirm that these grades are close to ‘per plan’ and are higher than the primary spillway elevation. a. Surveyed lowest overtopping elevation is 4952.30. Per the approved Drainage Report, the max ponding depth in the truck court is 4952.00. Driveway is in compliance with approved plans. 7. Perform clean up along the storm outlet channel along Redwood Street at the southwest corner of the site. This drainage channel appears to be obstructed and not functional. Please remove the riprap, regrade the swale, and reinstall riprap so that flows are not obstructed. The downstream plastic culvert also needs to be unburied and unclogged. (see attached picture). a. Cleanup has been complete. 8. Provide evidence that there is a portable stormwater pump on site. This is to satisfy the development agreement requirement to have pump on site. a. Pump, 200’ of extension cord, and 100; of hose are stored in the fire sprinkler room on Building 2 9. Once these items are addressed. Please upload to the State SDI notification website. a. We will upload after WW engineering signs off on these comment responses. 10. Please update site cert per attached redline comments and resubmit after items are addressed. a. Done. NEW Comment on 4/19/23: With this said, there is a bigger problem with the drainage patterns at the NW corner of Redman and Frontage Rd. I stopped by the site last week on Friday for a quick look while I was at Tractor Supply, it also happened to be raining at the time. The drainage design is for flows from the Frontage Road, in front of your site, to turn west on Redman Drive and proceed to Cooper Slough, however the flows at this corner are not being contained on the north side of Redman Drive and are proceeding south to the swale onto the Poudre Valley Coop property drainage system. Please see the images below and attached pictures. Your team will need to figure out a solution for this. The 2 ideas that come to my mind are: 1. Add additional asphalt paving to Redman Drive to construct a better road crown that would contain flows on the north side of Redman Drive, consistent with the approved drainage plan. a. This plan is preferred, see below for markup on proposed solution. 2. Provide an updated drainage analysis showing these flows crossing to the south side of Redman. This would need to evaluate the preproject and post project capacity of this drainage system. Agreements from any private drainage owners (if impacted) may be needed. Then a proper cross pan would need to be installed. This would include an amended drainage report and revised utility plan set. a. This option is not viable, during design, a drainage analysis was performed, and it was found the ditch along Redman Dr. does not have capacity to drain this drainage basin due to a very low slope. Proposed Solution: Fl a t i r o n s , I n c . La n d S u r v e y i n g S e r v i c e s ww w . F l a t i r o n s I n c . c o m 12/14/22 Joshua Breedlove Digitally signed by Joshua BreedloveDN: C=US, E=jbreedlove@flatironsinc.com, O="Flatirons, Inc.", CN=Joshua Breedlove Date: 2022.12.14 10:26:12-07'00' Fl a t i r o n s , I n c . La n d S u r v e y i n g S e r v i c e s ww w . F l a t i r o n s I n c . c o m 12/14/22 Fl a t i r o n s , I n c . La n d S u r v e y i n g S e r v i c e s ww w . F l a t i r o n s I n c . c o m 12/14/22 Fl a t i r o n s , I n c . La n d S u r v e y i n g S e r v i c e s ww w . F l a t i r o n s I n c . c o m 12/14/22 2'-0 " Fl a t i r o n s , I n c . La n d S u r v e y i n g S e r v i c e s ww w . F l a t i r o n s I n c . c o m 12/14/22 LEGEND NORTHNORTH MULBERRY CONNECTION DESIGN AND AS BUILT SURFACE EXHIBIT 01/24/2023 © PROJECT NAME: PROJECT NUMBER:096755001 CALCULATED BY:ABK CHECKED BY:HMM DATE:12/2/2022 Volume = (D/3)(A + B + (AB)^(1/2))D=depth between two contours, ft A=area of bottom contour, SF; B=area of top contour, SF ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.)(CU FT)(CU FT)(AC-FT) 4949 1,531 0 0 0.00 4949.1 3,444 242 242 0.01 4949.2 5,391 438 680 0.02 4949.3 19,253 1,161 1,841 0.04 4949.4 21,947 2,059 3,900 0.09 4949.5 23,698 2,282 6,182 0.14 4949.6 25,663 2,467 8,649 0.20 4949.7 28,261 2,695 11,344 0.26 4949.8 30,588 2,942 14,286 0.33 4949.9 32,701 3,164 17,450 0.40 4950 34,590 3,364 20,814 0.48 4950.1 36,657 3,562 24,376 0.56 4950.2 39,579 3,811 28,187 0.65 4950.3 42,089 4,083 32,269 0.74 4950.4 43,287 4,269 36,538 0.84 4950.5 44,162 4,372 40,910 0.94 4950.6 44,856 4,451 45,361 1.04 4950.7 45,465 8,962 49,873 1.14 4950.8 46,029 9,088 54,449 1.25 4950.9 46,540 9,200 59,073 1.36 4951 46,954 9,298 63,748 1.46 4951.1 47,364 9,390 68,463 1.57 4951.2 47,758 9,471 73,219 1.68 4951.3 48,159 9,552 78,015 1.79 4951.4 48,581 9,634 82,852 1.90 4951.5 49,005 9,716 87,732 2.01 4951.6 49,428 9,801 92,653 2.13 4951.7 49,850 9,885 97,617 2.24 4951.8 50,272 9,970 102,623 2.36 4951.9 50,695 10,054 107,672 2.47 4952 51,521 10,179 112,802 2.59 STAGE-STORAGE ANALYSIS Detention Pond DETENTION BASIN PROJECT NAME:Detention Pond ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.)(CU FT)(CU FT)(AC-FT) 4951 141 0 0 0.00 4951.1 523 31 31 0.00 4951.2 1,362 91 122 0.00 4951.3 2,960 211 333 0.01 4951.4 5,224 404 737 0.02 4951.5 8,364 673 1,410 0.03 4951.6 11,916 1,009 2,419 0.06 4951.7 16,353 1,408 3,827 0.09 4951.8 22,040 1,913 5,739 0.13 4951.9 29,559 2,571 8,310 0.19 4952 39,551 3,443 11,753 0.27 4952.1 50,645 4,498 16,252 0.37 ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.)(CU FT)(CU FT)(AC-FT) 4949 1,531 0 0 0.00 4949.1 3,444 242 242 0.01 4949.2 5,391 438 680 0.02 4949.3 19,253 1,161 1,841 0.04 4949.4 21,947 2,059 3,900 0.09 4949.5 23,698 2,282 6,182 0.14 4949.6 25,663 2,467 8,649 0.20 4949.7 28,261 2,695 11,344 0.26 4949.8 30,588 2,942 14,286 0.33 4949.9 32,701 3,164 17,450 0.40 4950 34,590 3,364 20,814 0.48 4950.1 36,657 3,562 24,376 0.56 4950.2 39,579 3,811 28,187 0.65 4950.3 42,089 4,083 32,269 0.74 4950.4 43,287 4,269 36,538 0.84 4950.5 44,162 4,372 40,910 0.94 4950.6 44,856 4,451 45,361 1.04 4950.7 45,465 4,516 49,877 1.15 4950.8 46,029 4,575 54,452 1.25 4950.9 46,540 4,628 59,080 1.36 4951 47,095 4,682 63,762 1.46 4951.1 47,887 4,749 68,511 1.57 4951.2 49,120 4,850 73,361 1.68 4951.3 51,119 5,012 78,373 1.80 4951.4 53,805 5,246 83,618 1.92 4951.5 57,370 5,558 89,176 2.05 4951.6 61,343 5,935 95,111 2.18 4951.7 66,203 6,376 101,487 2.33 4951.8 72,312 6,923 108,410 2.49 4951.9 80,254 7,625 116,035 2.66 4952 91,071 8,561 124,595 2.86 100-YR (2.86 AC-FT) = 4952.00 4952.1 50,645 6,988 131,583 3.02 PARKING LOT PONDING COMBINED VOLUMES PROJECT NUMBER: CALCULATED BY:ABK HMM Stage (FT ) Detention Volume (CU FT) ParkingLot Volume (CU FT) Volume (AC-FT)Stage (FT)Volume (CU FT) ParkingLot Volume (CU FT) Volume (AC-FT) 4949 0 0.00 4949 0 0.00 4949.1 0 0.00 4949.1 242 0.01 4949.2 248 0.01 4949.2 680 0.02 4949.3 900 0.02 4949.3 1841 0.04 4949.4 1904 0.04 4949.4 3900 0.09 4949.5 3229 0.07 4949.5 6182 0.14 4949.6 4854 0.11 4949.6 8649 0.20 4949.7 6920 0.16 4949.7 11344 0.26 4949.8 9435 0.22 4949.8 14286 0.33 4949.9 12227 0.28 4949.9 17450 0.40 4950 15339 0.35 4950 20814 0.48 4950.1 18758 0.43 4950.1 24376 0.56 4950.2 22433 0.51 4950.2 28187 0.65 4950.3 26356 0.61 4950.3 32269 0.74 4950.4 30495 0.70 4950.4 36538 0.84 4950.5 34759 0.80 4950.5 40910 0.94 4950.6 39201 0.90 4950.6 45361 1.04 4950.7 43674 1.00 4950.7 49873 1.14 4950.8 48284 1.11 4950.8 54449 1.25 4950.9 52900 1.21 4950.9 59073 1.36 4951 57631 0 1.32 4951 63748 0 1.46 4951.1 62352 21 1.43 4951.1 68463 31 1.57 4951.2 67176 123 1.54 4951.2 73219 122 1.68 4951.3 81983 376 1.89 4951.3 78015 333 1.80 4951.4 86891 868 2.01 4951.4 82852 737 1.92 4951.5 81780 1689 1.92 4951.5 87732 1410 2.05 4951.6 86771 2936 2.06 4951.6 92653 2419 2.18 4951.7 91743 4733 2.21 4951.7 97617 3827 2.33 4951.8 96818 7231 2.39 4951.8 102623 5739 2.49 4951.9 101874 10607 2.58 4951.9 107672 8310 2.66 4952 107057 15001 2.80 4952 112802 11753 2.86 4952.1 16252 3.23 TOTAL 2.80 3.23 0.43 DATE: Difference (CU-FT) Mulberry Connection - Dentention Pond CHECKED BY: PROJECT NAME: 3/28/2023 96755001 Design Value As-Built Revised per comment to include as-built pond volume PROJECT NAME: PROJECT NUMBER:096755001 CALCULATED BY:ABK CHECKED BY:HMM DATE:12/2/2022 Volume = (D/3)(A + B + (AB)^(1/2))D=depth between two contours, ft A=area of bottom contour, SF; B=area of top contour, SF ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.) (CU FT)(CU FT)(AC-FT) 0 532 0 0 0.00 0.4 687 243 243 0.01 1.4 1,139 903 1,147 0.03 2.4 1,681 1,401 2,548 0.06 3.4 2,316 1,990 4,537 0.10 4.4 3,083 2,690 7,228 0.17 STAGE-STORAGE ANALYSIS Pond Inflow Basin POND INFLOW INFILTRATION BASIN PROJECT NAME: PROJECT NUMBER:096755001 CALCULATED BY:ABK CHECKED BY:HMM DATE:12/2/2022 Volume = (D/3)(A + B + (AB)^(1/2))D=depth between two contours, ft A=area of bottom contour, SF; B=area of top contour, SF ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.) (CU FT)(CU FT)(AC-FT) 4952 737 0 0 0.00 TOP OF MEDIA = 4952 4952.2 946 168 168 0.00 4952.4 1,143 209 376 0.01 4952.6 1,350 249 625 0.01 4952.8 1,564 291 916 0.02 4953 1,786 335 1,251 0.03 4953.2 2,016 380 1,631 0.04 4953.4 2,281 429 2,061 0.05 RIM OF INLET = 4953 ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.) (CU FT)(CU FT)(AC-FT) 4952 2,585 0 0 0.00 TOP OF MEDIA = 4952 4952.2 3,138 571 571 0.01 4952.4 3,540 667 1,239 0.03 4952.6 3,982 752 1,990 0.05 4952.8 4,458 844 2,834 0.07 4953 5,028 948 3,782 0.09 RIM OF INLET = 4952.92 ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.) (CU FT)(CU FT)(AC-FT) 4952 3,322 0 0 0.00 4952.2 4,083 739 739 0.02 4952.4 4,682 876 1,615 0.04 4952.6 5,331 1,001 2,616 0.06 4952.8 6,022 1,135 3,750 0.09 4953 6,814 1,283 5,033 0.12 REQUIRED WQCV = 4,702 cubic foot RAIN GARDEN A - SOUTH RAIN GARDEN A - COMBINED STAGE-STORAGE ANALYSIS BASIN A RAIN GARDEN A - NORTH PROJECT NAME: PROJECT NUMBER:096755001 CALCULATED BY:ABK CHECKED BY:HMM DATE:12/2/2022 Volume = (D/3)(A + B + (AB)^(1/2))D=depth between two contours, ft A=area of bottom contour, SF; B=area of top contour, SF ELEV.AREA VOLUME ACCUM. VOL.ACCUM. VOL. (FT)(SQ FT.) (CU FT)(CU FT)(AC-FT) 4952 5,365 0 0 0.00 4952.2 5,827 1,119 1,119 0.03 4952.4 7,051 1,286 2,405 0.06 4952.6 7,724 1,477 3,882 0.09 4952.8 8,446 1,616 5,498 0.13 4953 9,606 1,804 7,302 0.17 RIM OF INLET = 4953; REQUIRED WQCV = 3,264 CF STAGE-STORAGE ANALYSIS Rain Garden C RAINGARDEN C Active Scenario: 2-YR Profile Report Engineering Profile - Outfall (Mulberry AsBuilt.stsw) Mulberry Connection 4,945.00 4,950.00 4,955.00 -0+50 0+00 0+50 Station (ft) Elev at ion (ft) DETENTION POND OUTLET STUCTURE Rim: 4,951.02 ft Invert: 4,949.03 ft HGL: 4,949.77 ft POND OUTFALL FES Rim: 4,950.33 ft Invert: 4,948.73 ft HGL: 4,949.42 ft 38.0 ft of 15.0in RCP@0.008 ft/ftFlow=3.40 cfsVelocity=4.87 ft/s Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203- 755-1666 12/1/2022 StormCAD [10.03.04.53]Bentley Systems, Inc. Haestad Methods Solution CenterMulberry AsBuilt.stsw Active Scenario: 100-YR Profile Report Engineering Profile - Outfall (Mulberry AsBuilt.stsw) Mulberry Connection 4,945.00 4,950.00 4,955.00 -0+50 0+00 0+50 Station (ft) Elev at ion (ft) DETENTION POND OUTLET STUCTURE Rim: 4,951.02 ft Invert: 4,949.03 ft HGL: 4,949.77 ft POND OUTFALL FES Rim: 4,950.33 ft Invert: 4,948.73 ft HGL: 4,949.42 ft 38.0 ft of 15.0in RCP@0.008 ft/ftFlow=3.40 cfsVelocity=4.87 ft/s Page 1 of 176 Watertown Road, Suite 2D Thomaston, CT 06787 USA +1-203- 755-1666 12/1/2022 StormCAD [10.03.04.53]Bentley Systems, Inc. Haestad Methods Solution CenterMulberry AsBuilt.stsw Fl a t i r o n s , I n c . La n d S u r v e y i n g S e r v i c e s ww w . F l a t i r o n s I n c . c o m 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 =1000 ft 0.00 51 0.00 0.04 Watershed Area =12.31 acres 1.00 813 1.00 0.04 Watershed Imperviousness =70.0%percent 2.00 1,291 2.00 0.04 Percentage Hydrologic Soil Group A =0.0%percent 3.00 1,862 3.00 0.04 Percentage Hydrologic Soil Group B =100.0%percent 4.00 2,523 4.00 0.04 Percentage Hydrologic Soil Groups C/D =0.0%percent 5.00 21,459 5.00 1.58 5.50 23,698 5.50 2.18 User Input 17 6.00 42,088 6.00 2.65 6.50 44,162 6.50 3.05 7.00 48,159 7.00 3.40 8.00 91,071 8.00 104.86 WQCV Treatment Method =hours 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 50 Year 100 Year One-Hour Rainfall Depth =0.53 0.86 1.14 1.44 2.40 2.93 in Calculated Runoff Volume =0.572 0.797 1.094 2.062 2.640 acre-ft OPTIONAL Override Runoff Volume =acre-ft Inflow Hydrograph Volume =0.571 0.797 1.093 2.061 2.640 acre-ft Time to Drain 97% of Inflow Volume =38.1 37.3 36.0 31.0 27.2 hours Time to Drain 99% of Inflow Volume =41.6 42.1 42.6 43.4 43.2 hours Maximum Ponding Depth =5.05 5.38 5.77 6.63 7.04 ft Maximum Ponded Area =0.50 0.53 0.76 1.04 1.14 acres Maximum Volume Stored =0.417 0.589 0.825 1.657 2.098 acre-ft Location for 1-hr Rainfall Depths (use dropdown): Workbook Protected Worksheet Protected Stormwater Detention and Infiltration Design Data Sheet Mulberry Connection Detention Pond Fort Collins, CO ASBUILT SDI_Design_Data_v1.08_Detention Pond.xlsm, Design Data 12/2/2022, 10:28 AM WQCV_Trigger =1 RunOnce=1 CountA=1 Draintime Coeff=1.0 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 5 10 15 20 25 30 35 40 45 0.1 1 10 FLOW [cfs] TIME [hr] 100YR IN 100YR OUT 50YR IN 50YR OUT 10YR IN 10YR OUT 5YR IN 5YR OUT 2YR IN 2YR OUT WQCV IN WQCV OUT 0 1 2 3 4 5 6 7 8 0.1 1 10 100 PONDING DEPTH [ft] DRAIN TIME [hr] 100YR 50YR 10YR 5YR 2YR WQCV ASBUILT SDI_Design_Data_v1.08_Detention Pond.xlsm, Design Data 12/2/2022, 10:28 AM Page 1 of 9 OctobeDecember 28th, 2022 Matt Simpson, PE, CFM Water Utility Development Review Engineer City of Fort Collins 81 North College Ave. Fort Collins, CO 80524 RE: B210483 & B210486 – Infiltration basin Testing Mr. Simpson: Our team is working on closing out the site drainage for our Mulberry Connection project, located at 4036 and 3874 Redman Drive, in the City of Fort Collins. As part of the development agreement (dated June 7 th, 2021), the designed infiltration basin is required to infiltrate all standing water within 40 hours after the end of the rain. After several conversations with yourself and Adam Camp, we came to an agreement that the test, outlined below, will work to satisfy this criterion. Test: 1. Hydrant flow meter was connected to the fire hydrant at the southeast corner of the site. 2. Approximately 600 LF of fire hose was connected to the hydrant meter and routed to inlet D1. 3. The infiltration basin test will include pumping approximately 50% of the design volume (2541 CF, or 19,000 gallons) into the infiltration basin. a. Due to flow constraints at the fire hydrant, the water was pumped over a period of 4.5 hours. b. The infiltration basin must infiltrate the 19,000 gallons over a period of 20 hours. 4. Timestamped photos were taken at the start of the test, every hour after the start, when the meter was shut off, and 1 hour after the meter was shut off showing all the water infiltrated. Results: 1. The test started at 9:00 AM on Thursday, October 27th. 2. Water was pumped from 9:00 AM to 1:30 PM. a. 19,600 gallons were pumped into the infiltration bason over this time period. 3. There was approximately 1 inch of standing water in the infiltration basin at 1:30 PM 4. All water was successfully infiltrated by 2:30 PM (1 hour later). 5. We appreciate your review of this letter in regard to accepting our proposed parking count. Please contact me at (720) 441-4811 or at scassidy@comunaleproperties.com should you have any questions. Sincerely, Comunale Properties Shane Cassidy, P.E. Construction Manager 12/28/22 Page 2 of 9 Photos: 1. Screenshot showing fire hose routing 2. Picture showing hydrant meter setup Page 3 of 9 3. Picture showing hydrant meter reading at beginning of test (2,733,200 Gallons) 4. Picture showing infiltration basin at beginning of test Page 4 of 9 5. Picture showing hydrant meter 1 hour after test start 6. Picture showing infiltration basin 1 hour after test start Page 5 of 9 7. Picture showing hydrant meter 2 hours after test start 8. Picture showing infiltration basin 2 hours after test start Page 6 of 9 9. Picture showing hydrant meter 3 hours after test start 10. Picture showing infiltration basin 3 hours after test start Page 7 of 9 11. Picture showing hydrant meter 4 hours after test start 12. Picture showing infiltration basin 4 hours after test start Page 8 of 9 13. Picture showing hydrant meter after 19,600 gallons of water was pumped 14. Picture showing infiltration basin after 19,600 gallons of water was pumped Page 9 of 9 15. Picture showing infiltration basin 1 hour after 19,600 gallons of water was pumped 16. Picture showing infiltration basin 20 hours after 19,600 gallons of water was pumped MU L B E R R Y C O N N E C T I O N CI T Y O F F O R T C O L L I N S UT I L I T Y P L A N S A N D C O N S T R U C T I O N D O C U M E N T S OF 44 R Know what's below. Call before you dig. 46391 REENIGN ORP ENOISSEF COLORAD D O LICENSE LA L .SLEKEEHI AN D AN 05/14/21 NORTH 25 096501004_CD_STM PR I V A T E S T O R M P L A N A N D P R O F I L E NOTESLEGEND DocuSign Envelope ID: 616EAD35-076D-4E0E-880A-BB80D1285C30 7/14/2021 NA NA NA NA 7/30/2021 4943.00 49 4 9 . 3 1 179.2' 201.5' 49 4 8 . 4 0 49 4 8 . 3 8 156' 128' 49 4 7 . 1 5 49 4 6 . 9 1 49 4 6 . 8 7 49 4 6 . 1 3 49 4 6 . 0 9 184' 49 4 5 . 5 0 49 4 5 . 4 0 49 4 4 . 5 2 Dunrite Excavation Storm Asbuilts 2/4/2022 MU L B E R R Y C O N N E C T I O N CI T Y O F F O R T C O L L I N S UT I L I T Y P L A N S A N D C O N S T R U C T I O N D O C U M E N T S OF 44 R Know what's below. Call before you dig. 46391 REENIGN ORP ENOISSEF COLORAD D O LICENSE LA L .SLEKEEHI AN D AN 05/14/21 NO R T H 26 096501004_CD_STM PR I V A T E S T O R M P L A N A N D P R O F I L E NOTES LEGEND DocuSign Envelope ID: 616EAD35-076D-4E0E-880A-BB80D1285C30 7/14/2021 NA NA NA NA 7/30/2021 49 4 8 . 9 7 212' 30' 49 4 7 . 7 6 49 4 7 . 7 3 49 4 7 . 5 8 49 4 7 . 6 2 159' 49 4 6 . 9 1 MU L B E R R Y C O N N E C T I O N CI T Y O F F O R T C O L L I N S UT I L I T Y P L A N S A N D C O N S T R U C T I O N D O C U M E N T S OF 44 R Know what's below. Call before you dig. 46391 REENIGN ORP ENOISSEF COLORAD D O LICENSE LA L .SLEKEEHI AN D AN 05/14/21 27 096501004_CD_STM PR I V A T E S T O R M P L A N A N D P R O F I L E NOTES LEGEND NO R T H NO R T H NORTH DocuSign Envelope ID: 616EAD35-076D-4E0E-880A-BB80D1285C30 7/14/2021 NA NA NA NA 7/30/2021 49 5 2 . 0 2 49 5 3 . 7 7 49 5 2 . 0 1 49 4 9 . 5 7 49 4 9 . 6 8 21' 40'