Questions_and_Answers_-_140R4023R0029_0003.pdf

Potomac Dam No.5 Left Abutment Repair

140R4023R0029

Questions and Answers

Q1: The scope requires substantial excavation. Was a hazardous material soil analysis done for the existing soils. Is a report available for contaminated soils?

A1: No hazardous materials testing of the soil was performed.

Q2: DWG Sheet 1 Excavation Plan drawing note says: Remove existing river debris within turbidity curtain shown on 60006 and placement of rockfill buttress. Line item 1-7, 02 41 10 of the project Price Schedule, requires us to price clean-up for 350 SY of debris. Specification 510090 Pages 54-56 indicate the debris to be, wood logs, stone debris, or wood cribbing. The level of effort to remove stone vs wood debris is substantially different. How do we distinguish natural rock from stone debris or is the expectation to remove all rock? Would you consider changing the price schedule to a unit allowance for removal of tonnage?

A2: Photograph 57 in spec 51-00-90 shows "stone debris", but spec section 02 41 10 part

1.03 states that river debris only includes "woody debris and other deleterious materials" and "historic timber cribbing dam material". The design intent is to remove soft materials such as wood, timber cribbing, and garbage to create a solid foundation for the rock buttress.

Q3: DWG Sheet 1 Excavation Plan shows the layout of the turbidity curtain. Using the current layout wouldn’t the disturbed sediment flow over the dam and be sent downstream because the turbidity curtain doesn’t turn 90 degrees (going towards the shore) to tie into the lower-level curtain?

A3: Spec section 31 25 10 part 3.06 and drawing 3615-D-60006 require the contractor to install a "turbidity barrier" separate from the turbidity curtain that prevents sediments from flowing over the dam and leaving the work area. The means and methods are up to the contractor, but the specification gives some options and guidance.

Q4: Is it the intent that pedestrians will be detoured onto Dam No. 5 Road with no additional safety measures other than the detour ahead sign?

A4: Spec section 02 04 10 requires the contractor to develop a towpath detour plan to be submitted with the traffic control plan (Spec section 01 55 20) to Washington County.

Spec section 02 04 10 part 1.04E.1. requires the traffic control plan to include appropriate traffic control devices where traffic cross the towpath detour. Please see revised Specification section 01 55 20 - Traffic Control for clarity.

Q5: Per specification section 01 31 30, no systems were identified in the products section. Please provide examples of acceptable construction document management systems.

A5: Contractor's responsibility to provide a CDMS that meets the requirements of specification section 01 31 30.

Q6: In specification section 51 00 60, the link provided to access the underwater videos does not work. Please provide an updated link to view these files.

A6: Access to the underwater videos is controlled. Please see revised Specification section 51 00 60 for access instructions.

Q7: After analyzing the details provided in the drawing set and the bid quantity of CLIN 1-11, we believe that there is a discrepancy. Please verify quantity in Price Schedule 1 as our takeoff is coming up significantly lower.

A7: The quantity is correct.

Q8: Specification section 31 03 33 – 1.04. B. 2. references 3 major divisions. What do these 3 major divisions refer to?

A8: Contractor to determine the divisions based on how they would like to be paid.

Q9: Considering the lack of available area for staging, will the Bureau accept an offsite field office location?

A9: No. Field staff needs to be onsite.

Q10: Specification section 01 57 30 – 3.01. C. 2. b. references the National Pollutant Discharge Elimination System (NPDES) permit. Is this something that has been already applied for and furnished by the government?

A10: The contractor is responsible for acquiring the Notice of Intent (NOI) to gain coverage under a Permit for Stormwater Associated with Construction Activity for complying with the National Pollutant Discharge Elimination System (NPDES) permit.

Typically, this is completed online through the MDE system -https://egov.maryland.gov/mde/npdes/ . Any discharges apart from land disturbance for construction are required to be permitted by the contractor. See revised specification 01 57 30 for clarification.

Q11: In specification section 31 32 72 there is no indication on how to join/finish the revetment panels. Please provide detail and/or specification for joining of revetment panels (seams and openings).

A11: Connect adjacent revetment mats using manufacturer's approved cable connections (3.02.E). The contractor is required to submit product shop drawings showing grouted seam details, hardware anchoring details, mat-to-mat connection details, and other installation details to be approved (1.04.B.1.b). Articulating concrete block (ACB) revetment mats are to be installed according to approved shop drawings, the ACB manufacturer's installation instructions, and the requirements of 3.02.

Q12: Per sections 31 23 15 and 31 23 16 – Are there any other criteria aside from gradation that dictates suitability of clay backfill material (soil classification, permeability, etc.)?

A12: In addition to the gradation, dispersivity testing is required to ensure the backfill is not dispersive per part 2.01.G. of spec 31 23 15 and 31 23 16.