The URL can be used to link to this page

Home My WebLink AboutWPO201300021 Plan - As-built 2018-10-23COUNTY OF ALBEMARLE Department of Community Development 401 McIntire Road, Room 227 Charlottesville, Virginia 22902-4596 Phone (434) 296-5832 Fax (434) 972-4126 BISWM — Bond Inspection Storm Water Management Review Project: Plan preparer Owner or rep.: Received date: (Rev. 1) Date of comments: (Rev. 1) Reviewer: WP0201400071 Old Trail Village Block 12 (See Also WP0201300021, BISWM — 23 Jul 2018) Jimmy Taggart, PE; Bill Ledbetter —Roudabush, Gale & Associates, Inc. [BLedbetter(cr�,roudabush.com; JTaggartgroudabush.com ] 914 Monticello Road, Charlottesville, VA 22902 March Mountain Properties LLC [1005 Heathercroft Circle, Suite 100] Dave Brockman, dave(a)oldtrailvillage.com 24 Jul 2018 12 Oct 2018 (.PDF) 1 Aug 2018 23 Oct 2018 John Anderson Albemarle County Record Drawing Requirements (As -built) for VSMP review. This correspondence is preliminary to SWM facility inspection. Engineering plans to inspect this facility by 24-Aug, and send follow-up correspondence. Sheet 1 With respect to 15 listed items (Record Drawing Requirements), please also ref. Amendment to WP0201500066, Approved 12/l/17: 1. Item 6: Since landscaping is scheduled for Fall 2018, Albemarle is unable to reduce bond amount for plants. As - built showing installed location of plants is required. (Rev. 1) Addressed. Applicant response (d. 12-Oct 2018) states: `It is our understanding that the Engineering department is agreeable to a letter of guarantee on proposed double row of shrubs rather than hold the remaining bond amount. March Mountain is prepared to write 2-year letter of guarantee/warranty that states the hedges will be replaced by either the HOA or MMP upon damage, deficient plant health, or demand by the county. The double row of shrubs will consist of the species known as pyracantha or "firethorn" spaced 3' O.C. and reach maturity in 2 years. The hedges will be placed as a safety barrier along the accessible sidewalk route as well as the pedestrian trail. The species will provide a deeper hedge that gives a broad barrier while maintaining aesthetic appearance.' As follow-up: This is acceptable. Please submit letter. 2. Item 8: See sheet 4BB comments, below. (Rev. 1) Acknowledged. 3. Item 10: (Minor) —Revise text to read deed book. (Rev. 1) Addressed. 4. Item 11: (Discussed with County Engineer) Provide permanent safety fence, 6' height, per VESCH Std. & Spec. 3.01, per approved Amendment to WP0201500066, 9 /9A. Approximately 720' linear feet is required to protect the public against potential hazard. NWSE=642.5, bottom of wet pond elevation=635.86 (wet pond depth varies 6.5-7'). Ref. Design Criteria and Construction Specifications (VESCH 3.01). Provide gated access to SWM Facility. Post signs noting potential hazard (3.01, p. I1I-2, Design Criteria 4). Note: Sheet 4AA shows As - built gravel pedestrian trail skirting the wet pond. This trail (not shown on approved SWM Plan) magnifies risk. (Rev. 1) Addressed. Applicant response (partial): `Acknowledged. Hazard signs stating "No Trespassing/Risk of Drowning" will be installed per request.' Also, see #1, above. Engineering Review Comments Page 2 of 3 5. Item 12: Compaction - Approved WPO2015000666, sheet 9, Earth Fill Note 4 requires density test (Min. density =95% of maximum dry density); provide report. F&R Fill Monitoring report d. 6/8/18 indicates no density tests taken. Propose a test method to substantiate density of constructed —16' high earthen embankment. (Rev. 1) Partially addressed. Applicant response: `Acknowledged. Although the dam height in its entirety is 16', the amount of fill constructed across the existing dam was z4'. Geotech reports were completed during the original construction of the dam (block 11-2014?) and I will try to pull any records of density compaction showing 95% or more for that time. F&R reports indicated that lifts were completed in 4-6 inches across the dam and compacted with rammax and sheepsfoot rollers. The reports also indicate that small steel diameter rods were used to probe for the evaluation of fill replacement and compaction. All reports pertaining to fill evaluation and compaction were noted to be found satisfactory. I will reach out to F&R to inquire about the density compaction report for the recent berm work.' As follow-up: Please provide block 11, 2014 F&R reports. This is the time we evaluate construction reports in support of Construction Record drawings (reports required for bond release). 6. Third bullet: Sheet 9 of approved Amendment to WPO201500066 requires 10' Berm Min. Width. Label Berm Min. Width on sheet 4AA (variable width is insufficient; please label Min. field measured width). (Rev. 1) Addressed. 7. Item 14: Compaction reports are required to verify that fill compaction in dams. Although geotech observational reports are included, there are no compaction reports apart from visual observation reports. Compaction reports are required to reduce the SWM bond for this facility. (Also discussed with County Engineer.) (Rev. 1) Not addressed. Also, please see #5, above. Sheet 4AA 8. Label OP1, OP2, OP3. (Rev. 1) Addressed. 9. Show /label 70 L.F. of wood post ,guard rail. Ref. sheet 9, Amendment to WPO201500066 (detail, sheet 8). (Rev. 1) Addressed. Sheet 4BB 10. Install StormRax riser cap, per detail sheet 10, approved Amendment to WPO201500066, per discussion with County Inspector /Engineering. (Rev. 1) Addressed. 11. Install orifice debris cages, per Note, 4BB. (Rev. 1) Partially addressed. As -built label indicates to be installed by 10/19/18. Asfollow-up: Please confirm orifice debris cages have been installed. 12. Label As -built slope (pitch, 3: 1, etc.) upslope of forebay. (Rev. 1) Addressed. 13. Wet Pond and Total Basin As -built stage -storage report appear to contain duplicate elevation entries (642.00, Wet pond; 644.00, Total Basin) with inconsistent column values for Area. Please revise tables. (Rev. 1) Addressed. 14. Provide As -built dimensions for installed riprap. Confirm design dimensions meet design shown at approved sheet 10 (OP I, OP2, OP3). Recommend copy OP I, OP2, OP3 graphics to As -built. Label As -built riprap outlet protection (dimensions). (Rev. 1) Addressed. 15. Since volume of Wet Pond is 84% of design, and 89% of required (due to rock), provide original PE -seal signature on computations that verify that despite significant deviation from design, the as -built condition is equivalent to (or better than) design. (Rev. 1) Partially addressed. Applicant response: `Original PE seal will be added to verify that despite the deviation in design due to field constraints, the as -built volume of the basin (forebay and wet pond -to dam) does in fact, exceed the overall required volume and is understood to meet the intent of water quantity/quality requirements. Furthermore, Old Trail is currently carrying a small surplus of treatment acreage based on the full development of stormwater management and can be utilized as necessary should the design be deemed insufficient, which is currently not the case provided [given] the as -built information.' Asfollow-up: Please add PE -certification outlined in Applicant response to Sheet 1. 16. Design Parameter Outlet #5 (Grass Emergency Spillway) Inv. Elev. (644.94') does not match profile Inv. Elev. (648.05'); revise, and perform routing, as needed. (Rev. 1) Addressed. Applicant response: `644.94' was a typo and carried over from the orifice elevation. The as -built spillway has been verified and elevation is correct @ 648.05. Text has been revised to reflect as -built conditions.' 17. Design parameters report total discharge=187.57 cfs; outlet #1 discharge=133.64 cfs. Label Design Parameter Data (1-, 2-, 10-, 25-yr, etc. routing), so these discharge values have context. (Rev. 1) Addressed. Applicant response: `The total discharge reported is from the multiple discharges at each stage of the system (i.e. the discharge from orifice 1, 2, 3, spillway, etc.). It is a total summation of each measure in the system based on an entered value of known/assumed headwater and tailwater conditions. This is not relevant to the storm event routings but rather what the total system has potential to discharge from the inflow.' 18. Provide routing output for Qlo-year pre -/post -development events, for comparison with reported pre -development Qlo_,e Engineering Review Comments Page 3 of 3 =28.81, and post -development QIO-,a, =18.23 cfs. (Rev. 1) Addressed. Please feel free to call if any questions. Thank you 434.872-4501 —0069 WP0201400071 BISWM As -built 102318-revl