9246 Addendum 3.pdf

Department of Public Works

Engineering Division James M. Wolfe, P.E., City Engineer City-County Building, Room 115 210 Martin Luther King, Jr. Boulevard Madison, Wisconsin 53703 Phone: (608) 266-4751 Fax: (608) 264-9275 engineering@cityofmadison.com www.cityofmadison.com/engineering

November 2, 2022

NOTICE OF ADDENDUM

ADDENDUM NO. 3

CONTRACT NO. 9246

TOPOGRAPHIC SURVEY AT ROBIN GREENWAY AND WEST TOWNE POND

Revise and amend the contract document(s) for the above project as stated in this addendum, otherwise, the original document shall remain in effect.

RESPONSES TO QUESTIONS RECEIVED:

Question: Items 18 and 19 specify getting sanitary and storm sewer structures and inverts 500 feet beyond the site limits. This adds a substantial amount of work and I’m wondering if this is really needed.

Could you please verify this requirement. Item 13 above already includes one structure upstream and downstream for sanitary and storm sewer.

Answer: Survey of one upstream and downstream structure rim, type, size and invert outside of property limits. Do not need to survey sanitary and storm sewer structures and inverts 500 feet beyond the site limits. A map of existing public storm and sanitary sewer is available at: https://data-cityofmadison.opendata.arcgis.com/

Question: Item 22 asks for the depth of water and sediment. Is this asking for the top of sediment elevation and the hard bottom elevation?

Answer: To the best extent possible, determine sediment depth based on the below.

Top of sediment may be determined using single beam sonar with control points verified by the City of Madison or standard rod method. The City of Madison hosts Madison GPS Base as part of the WDOT GNSS reference station network. More information is available: https://www.cityofmadison.com/engineering/developers-contractors/surveyor-toolkit

Sediment depths using sonar shall determine top of sediment, and shall be spot checked using rod method.

Bottom of pond depths shall be determined by the surveyor using best available data by evaluating sediment core logs (provided by the City), plan designs (provided by the City), and field confirmation using rod method where to survey through sediment to try to determine pond bottom elevation. Equipment for sonar shall have a specification of a minimum 1% of measured depth accuracy.

Question: Can you confirm if the trees will be tagged on either of these projects?

For all locations, trees will be tagged.

REVISE:

Attachment B Scope of Services:

GENERAL SURVEY REQUIREMENTS

13. The survey shall extend as least 50 10 feet beyond the improvements within the project boundary (unless there are fences/blockages not allowing access to adjacent property). For areas adjacent to streets, curb and sidewalk shall be surveyed. The Contractor shall assume that they shall survey a minimum of one structure and culvert ends (and in some instances more) upstream and downstream of the survey limits, for both storm and sanitary sewer, when they are present. Manhole inspections shall not be required with the survey work. The survey shall be of sufficient detail to collect offsite adjancent property information that may impact construction and design including signficiant trees, drainage patterns, structures, and utilities.

Assistant City Engineer Bryan Cooper, AIA

Gregory T. Fries, P.E.

Chris Petykowski, P.E.

Deputy Division Manager Kathleen M. Cryan

Principal Engineer 2 John S. Fahrney, P.E.

Janet Schmidt, P.E.

Principal Engineer 1 Christina M. Bachmann, P.E.

Mark D. Moder, P.E.

Financial Manager Steven B. Danner-Rivers

11/2/2022-9246 Addendum 3.docx

16. Minimum survey shot spacing along the greenway shall be shall be twenty-five (25) foot intervals perpendicular to the drainage way centerline along the project limits. Closer spacing may be required to adequately define topography. Full cross-sections shall be recorded at twenty-five (25) foot intervals perpendicular to the street centerline along the identified project limits. The Contractor shall collect sufficient data to create breaklines that accurately record topographic features, including but not limited to, flow line, secondary channels, tops of banks, bottoms of banks, channel meanders, channel thalwegs, secondary channels, floodplains, etc. All break lines shall be defined including, but not limited to, flow line, top of bank, bottom of bank, centerline of street, top of curb, edge of gutter, flow line, edge of pavement and sidewalk. The elevation of all driveway centerlines shall be recorded at the flow line, edge of gutter, both edges of sidewalk and 10 feet beyond the Right of Way. Full greenway cross-sections shall be recorded at a minimum of twenty-five (25) foot intervals perpendicular to the greenway. The Contractor shall be prepared to collect additional data, if necessary. All area outside the channels for West Towne Ponds shall be at a minimum 50’ grid or smaller as necessary to adequately define topography. For the soccer fields at West Towne Pond a 50’ grid for survey shots can be used.

DELETE

Requiring only one structure/culvert end upstream and downstream per item 13 above.

18. The location and invert elevations of all culverts, pipes, and structures used for storm sewer or sanitary sewer five hundred (500) feet beyond the site limits and containing two or more structures.

19. Center locations and rim elevations of all storm sewer structures and sanitary sewer structures five hundred (500) feet beyond the site limits and containing two or more structures.

20.

ADD

SURVEY DELIVERABLES

Additional report requirements.

7. Report outlining bathymetric survey data collection and equipment process including: benchmark locations, equipment, WSE readings, equipment specifications, data collection and processing method and results. An example can be found here:

https://www.cityofmadison.com/business/pw/contracts/documents/9433%20220627_SpringHarborBathy_Fin alReport.pdf

James M. Wolfe, P.E., City Engineer

CC:

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