RFI_1_responses_Revision_1_0003.pdf

Solicitation No. 140P2023R0027 – NACE 226875 Oxon Cove Trail RFIs

On sheet 55, there is a note which indicates that the approach rails are to be built of 4x4 posts to match the bridge. The bridge design may require chord member sizes larger than 4x4. If that is the case, will the rails need to be enlarged accordingly, or can they remain 4x4 in order to maximize cost‐effectiveness?

The intent to keep the bridge as “light visually” as possible,but will not sacrifice structural integrity which will dictate. Submittals prior to installation will be required for NPS acceptance.

On sheet 57’, the “Bridge Elevation” detail dimensions the bridge length as 60’, however the notes on that detail describe it as 70’. Please clarify.

The bridge is designed to be 60’ in length. The note on the titleblock for the drawings should have been changed to 60’ long. The structural sheets are also appropriate for the 60’ length.

It is unclear if the desired pedestrian bridge type is a truss or rolled girder. The bridge elevation on sheet 57 shows it as a rolled girder, however the section view on that sheet shows a truss. Please clarify.

The structural calcs and details are associated with a truss bridge.

Please consider a significant extension to the required completion time of 160 days. Unfortunately, this does not align with current prefabricated bridge industry conditions, and we would likely not be able to deliver this bridge until probably late 2023 or the first quarter of 2024 at the earliest, depending on how quickly the contract is awarded and time taken to review and approve shop drawings. If an extension to this date is not provided, then we are likely not going to be able to provide a quote to bidding contractors for our bridge.

The Period of Performance begins at NTP not at award. on‐site portion of the work cannot begin without the NTP. Upon award, submittals can begin, just no on‐site activities. The NTP start date can be adjusted to meet up with approved submittals of longer term items. Intent is to keep the physical on‐site construction period to a minimum duration possible .

Sheet L.01 and Specification Section 01 11 00 reference a geotechnical report which shows limits and depths of landfill debris. We are unable to find the referenced reports within the project solicitation documents. Can you please provide these or clarify where these are located within the solicitation documents?

See the attached geotechnical report.

The PSP provided shows a form which appears to be intended to be filled out for references.

However, this is a simple PDF and does not have the ability to “Choose an item” for example.

Can you provide a “live” document that can be selected?

See the attached general references form.

There are numerous references to the landfill area which state ‘refer to contract documents for scope’ but do not provide a specific reference. Please clarify the project scope limits in regard to the encountering trash or landfill debris. We do see, for example a requirement to monitor landfill gas within scope, but it does not appear that any gas collection or sealing systems are included as part of the base scope.

The design documents show grades and are intended not to hit the landfill layer. The limits of the landfill are shown on the plans.

Specification Section 01 35 29, Health Safety Plan, states “Special considerations shall be given to intrusive or high‐risk tasks and the potential for exposure to those performing such tasks.

Refuse excavation and landfill gas pipeline work are considered intrusive and high‐risk tasks.

Refuse excavation and landfill gas pipeline work are not included within the general project scope. Please clarify

The intent is to not hit the landfill layer. The gas line is intended as a “heads up” notation, as it is located on the drawings and may be encountered. The contractor is required to call location services prior to excavation. The powerline ROW is also attached for review and is outlined in the plans.

Specification Section 01 40 00 refers to an attached STSI. We are unable to locate this document, please clarify.

Contractors are required to provide any structural testing inspections completed in your engineer or vendor’s engineer's format.

Would you consider a 1‐week delay in receipt of proposals?

Yes, the proposal due date will be extended by 7 calendar days.

The project specifications mention stabilized stone and topsoil, however we are unable to locate where this is intended to be used as it is not shown on any of the typical sections called out.

Please clarify the requirement.

There is no soil with stabilizer on the project. There is the aggregate topsoil for shoulders along the trail edges and there is rip‐rap used for stabilization of the riverbank and for scour protection.

The bridge alternate drawings refer to 4000psi concrete for the deck and structure.

Specification section 03 30 00 2.10 references a 4000‐psi mix but it is indicated “for buildings”, is this the intended mix for the bridge deck and structure? Can a Maryland SHA standard mix be designated for these items?

For decking concrete, preference is to coordinate with the manufacturer for recommendation of structural property requirements of concrete. For abutment work, NPS prefers to follow the structural engineer’s specification.

Detail 1 Sheet 4.2 applies to the following questions “8 inches crushed washed 2‐inch diameter stone compacted to 90% density” There is no way to compact a clear 2” diameter stone in this way, please clarify. Additionally, is this intended to be the “weathered granite” stone referenced in the specifications?

Agreed that 2” stone cannot be compacted to 90%. It is the preference to only over‐excavate shoulders where necessary due to drainage or stability issues.

Preference is to shoulder the edges of the trial to meet grade using either topsoil or a blended soil/aggregate that can be revegetated. If stone is required in specific areas, it needs to be an angular granite or similar material.

Sheet C 2.5 shows existing subgrade undisturbed, yet 4.2 shows additional excavation for this topsoil/stone layer. Please confirm the additional excavation or please clarify one of the details for consistency.

It is the intent to only over‐excavate shoulders where necessary. Preference is to shoulder the edges of the trial to meet grade using either soil or a blended soil/aggregate that can be revegetated.

This detail shows topsoil placed directly upon a 2” open graded stone with no fabric, choke stone, or other separation layer. We believe this will cause migration of the topsoil into the voids of the 2” stone underlying. Please confirm this is your intended installation.

It is the intent to only over‐excavate shoulders where necessary. Preference is to shoulder the edges of the trial to meet grade using either soil or a blended soil/aggregate that can be revegetated.

Detail 1 Sheet 4.2 a show a maximum depth of excavation of 10”, specification section 02 41 00

3.4 G requires grubbing to a depth of 18”. This seems inconsistent with the overall concern of excavation within the landfill area to grub an additional 8”, please clarify.

Maintain 10” clearing/grubbing typical with the caveat of removing vegetation inclusive of roots

Specification 02 41 00 3.5B indicates asphalt “shall be broken up, hauled and disposed off site” while 3.7 says “Existing asphalt shall be pulverized to use as fill on site.” Please clarify.

NPS will allow use of pulverized asphalt as base material directly under new pavement provided it meets the specified compaction requirements per specification. If contractor proposes to fully remove asphalt, then it shall be removed in its entirety.

Specification 32 12 16 calls for a prime coat. Given the proximity to natural areas and adjacent streams, please confirm this is desired.

No prime coat required with asphalt.

Specification 32 12 16 2.3A identifies a base and surface mix (19mm and 9.5mm specifically), Sheet C 2.5 shows the paving detail and shows only 4” of “surface mix.” Please clarify the intended pavement section.

One lift per drawings of 9.5mm Section 32 12 16 Part 3 3.1.B.3 indicates excavation of soft soils when proof rolling existing subgrade, which consists of excavation beyond project limits. How is this paid for?

There should be no excavation outside of project limits. If soft soils are encountered beyond what is anticipated in the project documents, it would be treated as a differing site condition.

Section 32 12 16 3.3 indicates geotextile none is shown on the plans. Where is this geotextile to be located as the pavement section shows “surface asphalt” with a single lift as per 3.4.A.2

No geotextile is anticipated per plans. The only indication of Geotextile is with the turbidity curtain

Section 32 15 40 refers to Soil Shield LS sol stabilizer. Where is this intended to be used, as we cannot find anyplace this is indicated.

There is no soil stabilizer in this project.

Sheet 3.10 and 3.11 show turbidity curtains with no stream diversion or dike, are we able to place riprap with the turbidity curtain alone or are we required to make a dry area for placement?

The turbidity curtain is sufficient as it is not anticipated for over excavation within the water. Refer to plans for turbidity curtain details.

Sheet 3.10 shows live stakes in riprap, how are the stakes to be anchored in riprap as the detail shows normal soil.

Stakes would only be in locations of soil where required in the drawings. Any rip rap areas will not receive live stakes.

Page 8 of 56 of the Solicitation states “…new bollards…” Bollards are not shown on the Drawings. Please confirm bollards need to be furnished and installed. Please provide the locations and details for the new bollards. Bollards are not a requirement of the project

Please provide the location of the laydown site that will permit the concrete truck to pour concrete onto the bridge abutment.

Concrete trucks can access the site from either end of the new bridge location. If accessing from the Forest hills park side. Access is available on the far side of the new bridge through Forest Hills Park. They do require a permit/coordination through a relatively quick process. They are aware of the need and have had discussions with NPS on the matter.

Please provide the access point/s where a tractor trailer can deliver the pre‐manufactured bridge.

Access is available on the far side of the new bridge through Forest Hills Park. They do require a permit/coordination through a relatively quick process. They are aware of the need and have had discussions with NPS on the matter.

The current lead time for the bridge is 9‐months from purchase order. Would NPS be willing to consider extending the Period of Performance to allow for this long lead time item?

The performance period is set by the notice to proceed date. All submittal, shop drawing process, field verification and all other non‐site construction activities can begin upon award. The NTP can be coordinated for the time physical construction is to start so that activities can align with bridge delivery.

Please confirm the number of pedestrian and bicycle counting systems that we are to furnish and install. Reference: Drawing Set, Page 54 of 60, Sheet # L4.0, Detail 2. & Reference: Drawing Set, Page 43 of 60, Sheet# L3.0.

Two‐ One counter system as shown on sheet 43 near the entrance to the trail and one placed on the trail to the new ped bridge as shown on sheet 54

There are multiple statements in both the specs and drawings that read “…by others”.

Drawings, Page 59 of 60, S1.1 and Page 60 of 60, S1.2. “…pedestrian bridge by others”.

Please clarify

“pedestrian bridge by others” is a typo. The bridge was initially part of a separate project.

Page 57 of 60, L4.3 Shows the pedestrian bridge concrete deck and it states “…by others”. Please clarify.

“pedestrian bridge by others” is a typo. The bridge was initially part of a separate project.

Specifications, Page 264, 275 and 284, call for grade stakes “…set by others”. Please clarify.

Grade stakes are set by the contractor’s survey team Please confirm that we are to include the following in our proposal:

hiring a surveyor to set grade stakes and site layout.

Correct, a licensed surveyor shall be required furnish and install the pre‐manufactured pedestrian bridge.

Pedestrian bridge is part of the contract infill the bridge deck with concrete.

Correct, bridge deck shall be concrete The specs say we cannot stage on the trail. For the DC side of the bridge (we cannot cross) this would necessitate taking equipment and material out each night and remobilizing the next day, which will dramatically increase the cost. Is staging available on the DC side?

Staging can only take place on NPS property. Staging can be done from the fence on the DC side to the existing bridge or anywhere on the MD side along the trail and on hard surfaces. Access must be maintained along the trail entrance (MD side) to allow the park access to their maintenance area.

With the provision of the Geotech reports, it seems that the only place methane was encountered at an actionable level was 9ft depth. Given that we’re supposed to not disturb subgrade below the trail and only excavate a couple of inches beyond do contractors need to have an Industrial Hygienist onsite whenever work is performed? Also, is the 40 hours of training required for every worker?

Per Section 01 35 29 paragraph 1.3.4.a.1 'Employee Training": The contractor will not be required for the 40‐hour training plus 3 days field experience for all site personnel nor will an industrial Hygienist be required provided the means and methods proposed by the contractor do not require excavation beyond limits and depths indicated on the plans. The Health Safety officer however will require the HAZWOPER training outlined in the specifications and be present on site during the excavation work within the landfill envelope.