2017 Requests for Proposal
Dam Break Inundation Studies for Stony Creek, Waynesboro Nurseries, and Lake Wilda
Requests for proposal due by October 5th, 2017 at 2:00 pm. The RFP can be found here.
New PMP Values:
Unapproved Dam Break Inundation Studies:
South River #6
South River #7
South River #19
Answers to Questions Submitted by Prospective Respondents
Updated September 22, 2017
Question: Has inundation mapping been done for any of these dams, and if so, will it be available to us as a reference?
Response: Yes, an Inundation Report has been previously prepared, but not approved by Virginia Dam Safety. Hard Copies of the report is available. The consultant will be responsible for verifying the accuracy of the information contained in the Inundation Report.
Question: How far downstream from each of the three dams are cross-sections estimated to be needed, and/or how many cross-sections will need to be created?
Response: The computer model shall be extended to a point downstream of the impounding structure where the water surface elevations of the Spillway Design Flood (SDF) with and without dam failure converge to within one foot of each other or to the last impacted structure caused by a sunny-day dam failure, whichever is farthest downstream (4VAC50-20-54). Please note that DCR Dam Safety staff have encountered situations in the State of Virginia where the modeling of the required SDF (non-breach and breach events) has gone in and out of convergence more than once. As a result, the modeling of the SDF (non-breach and breach events) shall be extended downstream to the last point of convergence.
The consultant will be responsible for determining the minimum spacing between cross sections.
Question: Is there bare earth LIDAR data available below each of the dams, or will we need to hire a surveyor? If a surveyor is needed, are there typically seasonal limitations for field work due to weather? If a surveyor is needed, are there any places where access is a problem?
Response: It is my understanding that bare earth LIDAR data is available for the project area. (http://vgin.maps.arcgis.com/home/webmap/viewer.html?webmap=332c847160294b3e81665d3786e41aca)
The Professional Engineer will be responsible for determining if a surveyor is needed.
Question: Are there concerns or issues with any of the inundation studies we should be aware of (e.g., the inundation mapping will pass through a town).
Response: The Dams are upstream of Stuarts Draft and Waynesboro. South River Dam #19 Study, the Emergency Spillway flow from South River Dam #10A (VA#015004) will need to be addressed in the report.
Question: Have the various breaching flows already been determined, or will it be up to the consultant to calculate them? If the flows need to be calculated, is all the data available to do that, or will the consultant be making multiple layers of calculations (e.g., probable maximum precip and watershed runoff to get to PMP)? If multiple layers, do you know exactly what factors the consultant will need to determine and if the data is available to do that?
Response: The consultant will be responsible for developing breaching flows. Virginia PMP rainfall values have been developed for each dam. The consultant will be responsible for developing/verifying all information used in the report.
Question: Besides the field visits, how many meetings do you anticipate having with the consultant? How many days do you estimate the field visits will take?
Response: One initial meeting with the successful candidate to confirm contract terms and time table for completion. One progress meeting mid-way through work. Days to complete field visits is subject to many variables including the knowledge and training of the consultant’s work force and the equipment they provide.
Question: Are current bathometric surveys of the reservoirs available? Are there tables or curves with current area-contents-elevation data?
Response: There are not current bathometric surveys of the reservoirs. The reservoirs do have current area-elevation information.
Question: Will submissions from firms outside of the state be considered?
Question: Can the forms be provided in word format?
Response: They are posted on the Headwaters web-site.
Question: What are the height and capacities of the dams?
Response: The technical data sheets have been placed on the Headwaters web-site.
Question: Are bids being accepted on partial work.
Question: The RFP refers to Table 1 and or 2.
Response: There is no Table 2. Use Table 1
Question: Is the District willing to negotiate down the scope of work?
Question: Has the HSWCD determined to use the Virginia PMP rainfall data instead for these dams?
Response: Yes, the district is using the Virginia PMP rainfall values for the three dams.
Question: Are there copies of as-built plans available for review for any or all three dams?
Response: Yes, we have copies available.
Question: The RFP mentions coordinating access to the properties. What are the accessibility limitations for each dam if any?
Response: Notification of land owners is the only accessibility limitations for the three dams.
Question: If a firm or company is awarded the project, do they need to register to the eVA website?
Response: They only need to be registered with eVA if you are issued a purchase order document via the eVA eMall module.
Question: Are any previous dam breach studies or reports available for the three requested dams? If yes, what are the determinations of hazard classification? Can SWCD give the previous studies to us for review?
Response: An Inundation Report has been previously prepared, but not approved by Virginia Dam Safety. PDF copies of the report are available. The consultant will be responsible for verifying the accuracy of the information contained in the Inundation Report. The Dams have been classified as High Hazard dams.
Question: Is SWDC looking for a dam breach study for each dam for future planned land-use condition (ultimate condition) or present land-use condition (existing condition) or both?
Response: Present Land-use conditions.
Geometry data for dams and associated existing structures:
Question: Are as-built drawings for dams and associated existing structures available? Do we need to perform detail survey for the dams and associated existing structures?
Response: As-built drawings and design information is available for the existing structures. We do not believe that a detailed survey of the dam would be required.
Geometry data for downstream crossing structures and crossing roadway profiles:
Question: Are as-built drawings for roadway crossing structures downstream of those dams available? If not, can we measure the dimensions of cross structure by using basic tools, such as tape and rod. Can we get the roadway crossing profiles from the 1/9 arc-second DEM file if the as-built drawings for the existing roads are not available? Is it a SWCD requirement to perform details survey for those roadway crossings?
Reponse: As-built information on the downstream roadway crossing maybe available from VDOT. It is our understanding that field measurements are acceptable methods for collecting data for use in the model.
Geometry data for dam breach study domain:
Question: BAI checked with Augusta County GIS department, they can provide 4-foot topo file for the study area. DCR requirement for accuracy of topo is 5-foot contour. BAI will see county provided 4 -foot contour. The highest resolution topo is available at “The National Map – 3 DEP Products and Services”. The highest resolution map is One is 1/9 arc-second DEM file. Does SWCD prefer using 1/9 arc-second DEM file to the topographic modeling?
Response: The district would prefer using the bare earth LIDAR data for the project area. (http://vgin.maps.arcgis.com/home/webmap/viewer.html?webmap=332c847160294b3e81665d3786e41aca)
Breach flow direction:
Question: BAI will perform a field visit for each dam to determine the dam breach location, and will coordinate with DCR and SWCD staff to determine the final dam breach location and flow direction before performing the dam breach study. Our question is that only one dam breach flow direction will be simulated for current study, are we right? Any more than one dam breach flow direction will be excluded from the current RFP and will be counted as an extra.
Response: It is anticipated that only one breach flow location will be required.
How to determine the hazed class of the dams:
Question: Do we need to perform the standard procedure (recommended by DCR) for determining the standard hazard class of the dams? Based on the RFP, it sounds like we only need to perform a hazard class incremental analysis by using procedures listed in ACER-11 to determine the category of those dams, are we right?
Response: The Hazard Classification for this dam has been determined to be High Hazard. The request for the ACER-11 evaluation is to determine if the Classification can be lowered.
Question: Does SWCD want to consider the three dams as series or standalone?
Series means three dams will fail at the same time.
Standalone means that only one dam will fail at one time.
2017 Invitation for Bids
*Bids Due by 1:00 p.m. on Wednesday, June 7
Inch Branch (CANCELLED)