HomeMy WebLinkAboutWPO201300033 Certified Engineer's Report WPO VSMP 2016-11-16 tr,-:t COLLINS - 200 GARRETT ST,SUITE K CHARLOTTESVILLE VA 22902
434.293.3719 PH 434.293.2813 FX
www.collins-enginee ring.com
November 16, 2016
Albemarle County
Department of Community Development
Engineering Division
401 McIntire Road, Room 227
Charlottesville,VA 22902-4596
RE:Asbuilt Plan for WPO 201300033
Please allow this letter to serve as a certification that the bio-filter has been constructed to Albemarle
County standards, and the facility meets and satisfies the design requirements as specified in the
approved plans. An asbuilt survey for WPO 201300033 has been performed for the bioretention basin
on November 14, 2016. The survey was completed and certified by Cardinal Surveying. Collins
Engineering has inspected the basin and reviewed the asbuilt survey information,comparing it to the
design requirements for the basin. Upon reviewing the data provided by Cardinal Survey& Design and
conducting an onsite investigation of the facility, Collins Engineering has determined that the
bioretention basin has been installed per the approved plans,with some very minor deviations from the
approved plans as summarized below.The asbuilt survey confirms the installation of a riser, barrel and
emergency spillway outfall system.The attached record drawing also confirms the installation of the
forebay, mulch bedding,and cleanouts for the underdrains. Landscaping was also installed within the
bio-filter.
Below is a summary of the findings:
1. The original bio-filter proposed a minimum biofilter floor area of 540 SF. The constructed bio-
filter has a floor area of 558 SF;therefore,this meets the requirements.
2. The riser and outfall structure have been constructed per plan. The elevations are within
tolerance compared to the design elevations.
3. The basin provides a 1'storage capacity across the bio-filter floor area,and provides a 1'
overflow storage area, per the approved design.
4. The retaining wall varies slightly from the plan, but meets the overall design requirements for
the project.
5. The forebay volume meets the requirements from the approved plan. The forebay area is rip
rap, and there is little to no silt accumulation within the forebay.
Collins Engineering hereby certifies that this facility has been constructed per the approved design.
Please allow this letter to be accepted for the final release of the WPO bond.
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LL I N 5 200 GARRETT ST, SUITE K CHARLOTTESVILLE VA 22902
434.293.3719 PH 434.293.2813 FX
www.collins-engineering.com
May 31, 2017
Albemarle County
Department of Community Development
Engineering Division
401 McIntire Road, Room 227
Charlottesville, VA 22902-4596
RE: Asbuilt Plan for WPO 201300033
Please allow this letter to serve as a certification that the bio-filter has been constructed to Albemarle
County standards, and the facility meets and satisfies the design requirements as specified in the
approved plans. An asbuilt survey for WPO 201300033 has been performed for the bioretention basin
on November 14, 2016. The survey was completed and certified by Cardinal Surveying. Collins
Engineering has inspected the basin and reviewed the asbuilt survey information, comparing it to the
design requirements for the basin. Upon reviewing the data provided by Cardinal Survey& Design and
conducting an onsite investigation of the facility, Collins Engineering has determined that the
bioretention basin has been installed per the approved plans, with some very minor deviations from the
approved plans as summarized below.The asbuilt survey confirms the installation of a riser, barrel and
emergency spillway outfall system.The attached record drawing also confirms the installation of the
forebay, mulch bedding, and cleanouts for the underdrains. Landscaping was also installed within the
bio-filter.
Below is a summary of the findings:
1. The original bio-filter proposed a minimum biofilter floor area of 540 SF. The constructed bio-
filter has a floor area of 558 SF;therefore,this meets the requirements.
2. The riser and outfall structure have been constructed per plan. The elevations are within
tolerance compared to the design elevations.
3. The basin provides a 1' storage capacity across the bio-filter floor area,and provides a 1'
overflow storage area, per the approved design. 12:I por.Ln 4,441 f rej iati s`G�`f z /114441'4")
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4. The retaining wall varies slightly from the plan, but meets the overall design requirements for J
the project. r-1 ,„3 oq .\t. 4 ` ' 3°-6
5. The forebay volume meets the requirements from the approved plan. The forebay area is rip
rap, and there is little to no silt accumulation within the forebay.
6. The underdrain system and 1.5' of compacted stone around the underdrains have been installed
per plan. The underdrain system is 6” PVC perforate pipe.
7. The 2.5' of filter media was installed within the bio-filter per plan. The filter media was provided
by Luck stone.
In addition, Collins Engineering was contracted by the Peabody School to perform site and construction
inspections of the filling and grading, installation of utilities, and completion of the stormwater
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management on the project. Collins Engineering observed the installation of the fill associated with the
Bio-filter and the media material. Collins Engineering certifies that the material has been installed per
plan.
Geo-terrain Organization, Inc was onsite during the construction providing geo-technical testing on the
project. Attached are the soil reports from the geotechnical onsite testing. The testing included the
stormwater management facility area.
Collins Engineering hereby certifies that this facility has been constructed per the approved design. The
stormwater management facility receives the drainage as proposed with the approved construction
plans. The dam, underdrain system,and filter media have all been installed per plan. Please allow this
letter to be accepted for the final release of the WPO bond.
Sincerely,
10
Scott Collins, PE 1 fid,
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