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Home My WebLink AboutFile Documents.614 North St.0248.2017 (48).ARBK 592 Highway 133 Carbondale, CO 81623 Ph: 970-340-4130 Page 1 of 6 To: Hailey Guglielmo, PE City of Aspen – Engineering Department From: Adam Racette, PE Roaring Fork Engineering CC: Andy Mishmash, Ryan Lee Subject: 614 W. North Street As-Built Response Memo Dear Hailey, We are responding to the As-Built Survey comments addressed by the City of Aspen Engineering Department as part of the close out process for 614 W. North Street project through this memo. Please refer to the initial comments, with responses, below. 1. Page 8 of Civil Set shows existing retaining wall. Was this removed during construction? If not, please show. If it was removed does all drainage still go to the trench drain? - The existing retaining wall was removed during construction, due to field changes for the driveway approved by Justin Forman. A majority of the drainage on the driveway is collected by the trench drain. 2. Does the entire driveway drain into this trench drain? Upon visual inspection, it appears that a portion of the driveway may runoff into the alleyway. Please address. - Most of the concrete driveway runoff is collected by the trench drain, per as- built survey. The small triangle of concrete added where the existing wall was place, drains to the north in order to keep disturbance within the property lines. The runoff from the small triangle of impervious area is treated by the grass buffer, prior to sheet flowing back to the historical drainage pattern. 3. Call out trench drain size. - Trench drain size added to as-built survey. 4. Where does this 4" PVC tie to? - The 4” PVC stub has been removed. Reviewed by Engineering 05/21/2020 1:46:33 PM "It should be known that this review shall not relieve the applicant of their responsibility to comply with the requirements of the City of Aspen. The review and approval by the City is offered only to assist the applicant's understanding of the applicable Engineering requirements." The issuance of a permit based on construction documents and other data shall not prevent the City of Aspen from requiring the correction of errors in the construction documents and other data. April 23, 2020 Memo Page 2 of 6 5. The approved plans leave the existing 12" pipe in place to carry ditch flows . The removal of the pipe and construction of the ditch is not shown on the approved building plans. To make sure the ditch will not leak, the City has guidelines and inspections. Has anyone from the City approved this alteration or been out to inspect the installation (either Justin Forman or Rob Covington)? How was this ditch restored? Was a bentonite liner utilized? At what point adjacent to the neighboring property does it revert back to a pipe? - Justin Forman and Rob Covington have coordinated and approved of the ditch to be left open with the contractor. The ditch was restored and lined with bentonite, per Rob Covington’s request. The ditch is piped at the neighboring property line to the west. All work inspected and approved by Ditch Company. 6. Call out trench drain size. Plans call for 6". - Callout updated to represent 6” trench drain. 7. Plans show an inlet in the patio. Verify all drainage patterns match the approved plans. - Center drain removed from center of patio. The patio is now cross-sloped. All drainage from covered patio is collected at 6” trench drain or the grated lid at the drywells (low point of site). 8. Call out drywell diameter. Plans call out 5 foot diameter. - Drywell label updated to show 5’ diameter, 2-chamber drywell. 9. Verify and show an impermeable liner was installed along the foundation as shown on the building plans. - An image is provided below to show the impermeable liner installed along the foundation wall, per civil drawing requirements. April 23, 2020 Memo Page 3 of 6 10. The plans call out a recessed lid with sod covering the drywell. Put dimensions on the asbuilt so the drywell lid can be easily located for inspections and maintenance without digging up the whole front yard. - The drywell lid is now grated and at a low point in the front yard to capture any runoff from the impervious, covered patio. 11. Building plans require a two chamber dry well. Please demonstrate on the asbuilt that a two chamber dry well was constructed. - A two-chamber drywell has been installed, per revised as-built survey. 12. The plans call out two separate inverts. One from a downspout on the corner of the building, and one from the east storm line. If the pipe configuration differs but still functions please provide a drainage memo. - The storm alignment and pipe configuration has been altered from plans. Drainage tables to confirm the revised system has capacity for specified storm events is included with this memo, following all responses. April 23, 2020 Memo Page 4 of 6 13. Asbuilt conditions show a drywell depth of 10.63 feet. The plans call out a depth of 15.7 feet. Please address the discrepancy. The drainage plan states 10' depth is needed to account for the WQCV, however 15.7' was provided for additional detention and due to the pipe configuration. On the asbuilt it does not appear 10' is available without surcharging and overtopping. Is the Bottom elevation of 7880.2 really the elevation of the dividing champer? - The as-built survey has been updated to reflect that the drywell sump was installed as designed. The 7880.2’ elevation callout is, in fact, the top of the water quality chamber. The drywell sump at the second chamber (top of gravel) is 7875.1’. Please refer to revise as-built survey. 14. Building plans show a downspout here. The asbuilt does not. Where is this drainage routed? Is it the 2nd level deck drain? - The downspout had been shifted in the field. The new location of the downspout is against the structure, to the north of the old location. The revised pipe configuration conveyance calculations are included in this memo, following all responses. 15. Pipe configuration on the asbuilt does not match the building plans. This pipe is not shown on the building plans. Please address. - The revised pipe configuration conveyance calculations are provided in a table, following all responses. 16. The building plans show a downspout here. The asbuilt does not. Where is this drainage routed? - The downspout location had been shifted in the field. The new location of the downspout is at the AC Unit pad. This downspout is now part of the revised storm system to the west of the structure. Conveyance calculations are provided in this memo on the reconfigured storm system, following all responses. April 23, 2020 Memo Page 5 of 6 100 Year Sub Basin Peak Discharge Developed Calculations 1 Hour(P1)1.23 Return Period 100 Sub Basin Total Area Imp. Area Impervious C Value Time of C Intensity Sub Basin Flow Rate (Name)At (ft2)Ai (ft2)Ai/At (%)From Table (Td)I=88.8P1/(10+Td)01.052 Qsub (ft3/sec) 1.1 494.32 494.32 100.00%0.950 5 6.33 0.07 1.2 180.27 180.27 100.00%0.950 5 6.33 0.02 1.3 155.56 155.56 100.00%0.950 5 6.33 0.02 1.4 465.98 465.98 100.00%0.950 5 6.33 0.06 1.5 232.55 232.55 100.00%0.950 5 6.33 0.03 1.6 397.08 397.08 100.00%0.950 5 6.33 0.05 1.7 49.84 49.84 100.00%0.950 5 6.33 0.01 1.8 317.29 317.29 100.00%0.950 5 6.33 0.04 Storm System Pipes Pipe System Pipe Contibuting Sub-Basins Design Flow Rate Qdes AB1 1.1 0.07 AB2 1.1 0.07 AB3 1.1 0.07 AB4 1.8 0.04 AB5 1.1, 1.8 0.11 AB6 1.1, 1.8 0.11 AB7 1.1-1.8 0.32 A K=0.462 Pipe Design Flow Rate Proposed Slope Manning Coefficient Required Pipe Diameter Equation 4-31 Required Pipe Diameter Proposed Pipe Diameter Qdes (ft3/sec) S (%)n d (ft) = {nQdes/K√S}3/8 Dreq (in) Dpro (in) AB1 0.07 1.07%0.01 0.20 2.44 4.0 AB2 0.07 1.07%0.01 0.20 2.44 4.0 AB3 0.07 1.07%0.01 0.20 2.44 4.0 AB4 0.04 50.00%0.01 0.08 1.00 4.0 AB5 0.11 20.79%0.01 0.14 1.68 4.0 AB6 0.11 20.79%0.01 0.14 1.68 4.0 AB7 0.32 20.79%0.01 0.21 2.49 4.0 Pipe Sizing April 23, 2020 Memo Page 6 of 6 Pipe Configuration at Vertical Wye (Inv Out AB4, Inv In AB5) Pipe Design Flow Rate Proposed Pipe Diameter Slope 80% of Proposed Pipe Diameter Manning Coefficient Full Pipe Cross Sectional Area Full Pipe Flow Rate Q Design / Q Full d/D Hydraulic Grade Line (Depth of Flow) Depth of Flow Less Than 80% of Pipe Diameter Qdes (ft3/sec) Dpro(in)S (%)Dpro*.8 (in)n A (ft) = π (Dpro/2)2 Qfull (ft3/s) = A(1.49/n)((Dpro/48)2/3)S1/2 Qdes/Qfull (from Chart)d (in) = (d/D)*Dpro (Yes/No) AB1 0.07 4.0 1.07%3.2 0.01 0.087 0.256 0.27 0.38 1.52 Yes AB2 0.07 4.0 1.07%3.2 0.01 0.087 0.256 0.27 0.38 1.52 Yes AB3 0.07 4.0 1.07%3.2 0.01 0.087 0.256 0.27 0.38 1.52 Yes AB4 0.04 4.0 50.00%3.2 0.01 0.087 1.753 0.02 0.08 0.32 Yes AB5 0.11 4.0 20.79%3.2 0.01 0.087 1.131 0.10 0.24 0.94 Yes AB6 0.11 4.0 20.79%3.2 0.01 0.087 1.131 0.10 0.24 0.94 Yes AB7 0.32 4.0 20.79%3.2 0.01 0.087 1.131 0.28 0.41 1.62 Yes Hydraulic Grade Line and Pipe Capacity MARKED TNC LS38215WIT. CORNERELEVATION:7889.56FOUND REBAR &1-1/4" YELLOWPLASTIC CAP LS9184ELEVATION:7891.31SITE BENCH MARKFOUND REBAR & 1-1/4"YELLOW PLASTIC CAP LS9184ELEVATION: 7891.05SOUTH 84.62' N00°03'47"W 78.00'N75°09'11"W 51.68'(BASIS OF BEARINGS)S50°49'13"W 788.25'(TIE)10.5'2.9'10.4'3.4'3.2'26.9'28.5'6.7'WW3.5' 25.5'FFE7891.922 - STORYHOUSE &BASEMENT614 W. NORTH STREETASPEN - COLORADOEDGE OF ASPHALTBRIDGELOTS 14 & 15AREA: 4065± SQ.FT.0.093± ACRES1415131216NORTHSTREET5.0'SETBACK5.0'SETBACK10.0' SE T B A C K 17.0'4.2'2.9'4.2'3.4'8.0'WWPERVIOUSPAVER PATIOCOVEREDIMPERVIOUSPAVER PATIODRYWELL "A"5' DIAMETER- 2 CHAMBERSTRUCTURERIM:7890.834"PVC:II 7883.1TOP WQ SECTION:7880.2TOP OF GRAVEL:7875.1DS-INV:7888.88PERVIOUSPAVER PATIOFFE7890.88PAVERWALKDS-INV:7889.82DSINV:7887.544" PVC STORM(TYPICAL)INV:7889.06"TRENCHDRAIN7891.8TD-INV7891.50TD-INV7891.547890.897889.917890.577891.777891.807891.987891.883.0%3.0%3.0%4.0%2.0%4.0%1.0%2.0%2.0%7891.537891.78 4"PVCINV:7888.417890.197891.857891.84A.C. UNITSMAILBOXWOOD FENCE(ON PROPERTY LINE)1.5%CONCRETEPAD2.0%2.0%2.0%2ND LEVELDECK DRAINSTORM SYSTEM "A"STORM SYSTEM "A"12.8'3.5'GRATE7891.2INV@BEND7890.6INV@BEND7890.3789178907891 78917890 7891AsBuilt - 614 W North StreetEngineer: AMRDrawn By: VJTSheet Number:DateCommentsInit.Rev.Computer File InformationPrint Date: 5/18/20Drawing File Name:Project No.: 2017-33Sheet RevisionsROARING FORK ENGINEERING592 HIGHWAY 133CARBONDALE COLORADO, 81623PH: (970)340-4130F:(866)876-5873C1Of:C1614 W. NORTH STREETASPEN, CO 816111AS-BUILT PIPE EXHIBIT05.05.2020VJT