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Home My WebLink AboutSite Certifications - 12/02/2022FORBES ENGINEERING Full Service Civil & Structural Engineering November 28, 2022 Mr. Dan Mogan Development Review Engineer City of Fort Collins Stormwater 700 Wood Street Fort Collins, Colorado 80522-0580 RE: West Vine Drive Storage As-built Rain Garden Volume Certification Mr. Mogan, This letter is in regards to your request for a certification of the as-built rain garden flat area and volumes for the West Vine Drive Storage project. As you are aware, the initial construction of the rain gardens did not follow the original design. The forebays were not built and the volume for all three rain gardens was insufficient due to an over-loading of fill material along the retaining walls and in the areas along the face of the buildings. Since the initial construction, adjustments have been made to all three Rain Gardens to conform to the designed plans. The forebays were correctly installed and the elevation of the outlet weirs for each Rain Garden was raised and the over-fill along the walls of the west and middle rain gardens have been removed to provide the additional needed volume (see attached photographs). The following calculations are based on survey data elevations that were obtained during and after the recent excavation (see attached rain garden details). The revised rain garden volumes are as follows; West Rain Garden Revised Weir Elevation 5010.01 Top of Wall Elevation 5011.01 Minimum Flat Surface Area 1122 Square Feet Provided Flat Surface Area 2130 Square Feet Required Volume per spread sheet 1683 cubic feet Rain Garden Volume 3764 Cubic Feet Surplus Volume 2081 cubic feet 3 West Rain Garden Middle Rain Garden 1/19 Page 1 of 2 DURING CONSTRUCTION INSPECTION CHECKLIST To be completed by Construction Superintendent This checklist is to be completed during construction and included with the Overall Site and Drainage Certification. • 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. Project Name: West Vine Storage Date: 5/25/2022 Building Permit Numbers: See Attached Sheets for Permit numbers & finish floor elevations I. Compaction A. Yes All berms and embankments meet the compaction requirements as specified in the project geotechnical report or comply with the City’s standard, which is “soils should be compacted within a moisture content range of 2% below to 2% above optimum moisture content and compacted to 95% of the Maximum Standard Proctor Density (ASTM D698).” Compaction requires verification during construction. Provide testing log from contractor/engineer. II. Storm Drain Pipe Installation Requirements A. Yes The pipe trenches have been compacted in accordance with Section 02225-3.07.A.1. of the Fort Collins Development Construction Standards for Water, Wastewater, Stormwater (e.g., the trenches in the roadways are to be 95% of maximum density and all other areas are to be at 90%, both in accordance with ASTM D698). III. Energy Dissipation and Erosion Protection - FCSCM Chapter 9, Section 7.0 A. Riprap 1. Yes The riprap bedding is a granular bedding of the gradation and thickness indicated on the approved construction plans. 2. N/A A filter fabric was installed instead of granular bedding and is the material shown on the approved construction plans or was an approved equal. Provide documentation for an approved equal. 3. Yes The riprap is the gradation shown on the approved construction plans with a D50 of 9”. 4. Yes The riprap thickness is as shown on the approved construction plans and extends to the horizontal limits shown. 5. Yes The riprap is buried to the depth indicated on the approved construction plans. (A minimum of 6 inches of soil is required.) B. Permanent Erosion Control Fabric - FCSCM Vol.1, Ch.7 1. Yes All fabric was installed per manufacturer’s specifications. 1/19 Page 2 of 2 IV. Other Permanent BMPs A. Yes All cut-off walls have been installed in accordance with the approved construction plans. (Cut-off walls are required for irrigation ditch crossings of storm drain pipes.) V. Extended Detention Basins A. N/A Installation of this facility was verified via inspection by a City-Stormwater Inspector at the point of installation of the water quality control box(es). Provide date of inspection and name of inspector: N/A Included certification sheet(s): Please check the appropriate box(es) for the Low Impact Development (LID) facilities found on this site and complete the corresponding certification sheets. ☐ Permeable Interlocking Concrete Pavers ☒ Bioretention Cells (Rain Gardens) ☐ Sand Filters ☐ Vegetated Buffers ☐ Underground Infiltration ☐ Other LID – For certification of Dry Wells, Tree Filters, Constructed Wetland Channels & Ponds, etc., contact City Staff to determine requirements to exhibit the LID facility has been constructed and functions as intended per the approved drainage report. *Please provide photographic documentation of the installation of all stages of all LID facilities. **Please contact the City Stormwater Inspector at stormwaterinspection@fcgov.com to discuss inspection requirements for each LID facility and request inspections. ***All facilities being certified must be “clean” – free of sediment & construction debris – prior to certification or acceptance of the facility. Completed by: Name: Tracy Zwetzig, Kevin Forbes Title: Project Manager Email: taz@slbbi.com Phone: 970-567-0677 Company: Clark Enterprises Construction Address: 80 Factory Road Eaton CO, 80615 1/19 Page 1 of 3 Bioretention Cells (Rain Gardens) was held with City-Stormwater Inspector to discuss installation, inspection, checklist, and ☒ ☐ ☐ location (i.e. DCP, initial erosion control Underdrain and basecourse inspection(s): facility was verified via inspection by a City-Stormwater Inspector at the point of installation of the outlet, underdrain, geomembrane layer, and base course (per design in Final Plan ☒ ☐ ☐ inspector’s name Pea gravel and BSM inspection(s): was verified via inspection by a City-Stormwater Inspector at the point of installation of the pea gravel and bioretention ☒ ☐ ☐ inspector’s name vary Excavation ☒ ☐ ☐ ☒ ☐ ☐ ☒ ☐ ☐ ☒ ☐ ☐ Intake ☒ ☐ ☐ Forebay ☒ ☐ ☐ Provide photograph There is a minimum 3” drop at the forebay entrance ☒ ☐ ☐ Provide photograph Forebay will drain fully and not hold standing water ☒ ☐ ☐ Outlet Structure/Overflow Emergency overflow elevation is confirmed ☒ ☐ ☐ overflow to top of media filter; provide ☐ ☐ ☒ 1/19 Page 2 of 3 Overflow inlet invert elevation is at least 3 inches below containment wall/berm (to direct overflow into inlet) ☐ ☐ ☒ inlet and top of containment wall/berm; from erosion and maintain elevations ☒ ☐ ☐ photographs to be Impermeable Liner ☒ ☐ ☐ ☒ ☐ ☐ Provide photograph Impermeable liner is buried with no exposure ☒ ☐ ☐ Any penetrations of the impermeable liner have been sealed and checked for water-tightness ☒ ☐ ☐ Underdrain System ☒ ☐ ☐ Provide photograph At least one cleanout is provided per underdrain lateral ☒ ☐ ☐ Provide photograph Cleanout pipe is solid (not perforated/slotted) ☒ ☐ ☐ Provide photograph Cleanout covers are installed and watertight ☒ ☐ ☐ Provide photograph Verify the underdrain is NOT wrapped in geotextile fabric ☒ ☐ ☐ Provide photograph Verify there is no orifice plate on the underdrain outfall ☒ ☐ ☐ Provide photograph Underdrain integrity tested after backfilling using TV and/or water test ☒ ☐ ☐ underdrains have been Filter Media and Aggregate - meets design specifications ☒ ☐ ☐ record depth installed #8, #89, or #9): - meets design specifications ☒ ☐ ☐ record depth installed - meets design specifications ☒ ☐ ☐ record depth installed ☒ ☐ ☐ Provide load ticket BSM is installed flat and level ☒ ☐ ☐ Provide photograph Other Structural Components Containment wall/berm is continuous and level ☒ ☐ ☐ 1/19 Page 3 of 3 Landscaping Verify final landscaping is free of sod ☒ ☐ ☐ ☒ ☐ ☐ Provide photograph SiteVvisit verification Vegetation is planted according to landscape design specifications and final landscaping plan ☒ ☐ ☐ ☒ ☐ ☐ Temporary irrigation installed ☐ ☐ ☒ irrigation is installed to establish/maintain has been installed Close Out ☒ ☐ ☐ Northern Colorado Geotech November 11, 2022 2956 29th Street, Unit 21 Greeley, Colorado 80631 Phone: (970) 506-9244 Fax: (970) 506-9242 Clark Enterprises 80 Factory Road Eaton, Colorado 80615 Attn: Taz Re: West Vine Storage Fort Collins, Colorado Northern Colorado Geotech Project No. c173-19 Northern Colorado Geotech performed density testing of the soil on the top of the ditch berm in accordance with the request from the client. The soil appeared to meet standard industry specifications of 95 percent compaction. If you have any questions or if we may be of further assistance, please do not hesitate to contact us at (970) 506-9244. Sincerely, NORTHERN COLORADO GEOTECH Doug Leafgren, P.G. President Digitally signed by Doug Leafgren DN: C=US, OU=President, O=Northern Colorado Geotech, CN=Doug Leafgren, E=dleafgren@msn.com Reason: I am the author of this document Location: your signing location here Date: 2022.11.11 09:48:59-07'00' Foxit PhantomPDF Version: 10.1.9 Doug Leafgren 2956 29TH STREET, UNIT 21 GREELEY, COLORADO 80631 PHONE: (970) 506-9244 FAX: (970) 506-9242 SUMMARY OF FIELD DENSITY AND MOISTURE TEST RESULTS CLIENT: Clark Enterprises PROJECT: West Vine Storage 80 Factory Road LOCATION: Fort Collins, Colorado Eaton, Colorado 80615 ATTN: Taz NCG PROJECT No: c173-19 TECHNICIAN:DL REVIEWED BY: DML DATE: 11-Nov-22 TEST METHOD:DIRECT TRANSMISSION REMARKS: <> indicates failing test MATERIAL DESIGNATION:1 2 3 4 5 6 7 MAXIMUM DRY DENSITY: 118.5 120.5 112.0 122.0 OPTIMUM MOISTURE: 12.0 11.5 13.5 13.0 MOISTURE TOLERANCE:ц2 ц2 ц2 ц2 ELEVATION WET UNIT DRY UNIT REQUIRED TEST DATE LOCATION BELOW WEIGHT WEIGHT WATER PERCENT PERCENT MATERIAL No. TESTED FIN. GRAD PCF PCF CONTENT % COMPACTION COMPACTION DESIGNATION 95 11/8/22 Top of Ditch Berm - west side FG 125.8 114.8 9.6 95 95 MIN 2 96 11/8/22 Top of Ditch Berm - east side FG 125.4 114.3 9.7 95 95 MIN 2 20190049823 This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA This unofficial copy was downloaded on Aug-19-2020 from the City of Fort Collins Public Records Website: http://citydocs.fcgov.com For additional information or an official copy, please contact Engineering Office 281 North College Fort Collins, CO 80521 USA