B08_26-CHOH_241449_-_Combined_Final_Q_A_0007.pdf

RFI No. Question Final Response

Due to the technical nature of this project, additional time is needed to prepare this proposal. Additionally, many subcontractors and suppliers have indicated that they are unable to work up pricing within the allotted time frame due to Covid-19 outbreaks.

Please consider extending the bid date to July 1st.

Proposal Final Due Date is 2 PM Mountain Time Thursday July 28, 2022

Previous NPS DSC procurements have allowed for the submission of previously completed NAVFAC/USACE Past Performance questionnaires in lieu of the Attachment 8 Past Performance Questionnaires. Please consider adopting this procedure for this procurement.

Submit Past Performance information per requirements in Section L for FACTOR 7-PAST PERFORMANCE. A PPIPRS Evaluation Report is an acceptable substitute for the Past Performance Questionnaire.

On sheet C5.11 section 1, Temporary Pedestrian Bridge Detail, Note 1 indicates that the bridge is provided by The Park. Can you please provide photos, weight, shop drawings, or dimensions

See attached for photos. Bridges are located at C&O Canal NHP Maintenance Facility near Great Falls, MD near 39°00'20.1"N 77°14'40.6"W https://goo.gl/maps/SjC778LCinLAe9wUA. They can be viewed by the contractor at their convenience.

Amendment 2 that was posted included a blank sign-in sheet...FYI. I think you intended to include the completed version.

Corrected Attendance Sheet was included in Amendment #3.

Sheet C3.3 in the center of the page, there is a Text Callout "CLEARING AND GRUBBING" with three leaders, the leader on the right is not pointing to an area that is hatched similarly to the other sites that are being identified. Please confirm the locations for clearing and grubbing on sheet C3.3.

See hatching for clearing and grubbing defined in the legend. The call-out for the third leader to the right is in error. Revised drawings are attached.

Can you please provide photos of the culverts where the stream restoration work begins?

See attached for photos. The site is open to the public and contractor can visit to see the areas first hand at their convenience.

Can you confirm that the Temporary Water Diversion Pipe (TP-3) is to end on the west side of the Temporary Causeway Cofferdam Crossing? How is the water going to flow through an impermeable structure? There appears to be a Removal Pumping Station, but it is not clear where the suction line is to discharge. Please clarify.

The plan was revised to show the clear water diversion discharging to the east of the causeway.

Is a pre and post-construction survey required of the Potomac Interceptor Sewer?

If so, where is the closest access point to get inside the sewer line?

NPS clarified with DCWATER in regards to the standard requirements from that agency included on Sheet G2. Per DCWATER, Detailed pre- and post-construction surveys of the utilities and structures utilizing in-line methods (i.e. video inspection, sewer TV, combination TV and Sonar, etc.) is not required.

On sheet C4.2 a Temporary Access Path is indicated to be constructed on the south side of the C&O Canal Towpath. The plans show Temporary Timber Matting with the diagonal hatching however there is also a note identifying it to be a Temporary Sone Access Road. Please clarify.

Plans have been revised, use temporary timber matting as shown in the plans to prevent sub-grade compaction and reduce impacts to adjacent natural resources.

Due to the technical nature of this project, we need additional time to prepare the proposal. Please consider extending the bid

Proposal Final Due Date is 2 PM Mountain Time Thursday July 28, 2022

The details regarding the Gully Repair are unclear. Can you please provide a volume for the contractor to bid to fill the Gully Repair?

The site is open to the public and contractor can visit to see the areas first hand at their convenience to collect measurements of necessary earthwork. Detail has been revised.

What are the depth and diameters of the sinkholes?

The site is open and accessible to the contractor for their inspection.

Can you please provide the flow rate of each of the three tributaries so the proper dewatering pump may be sized accordingly?

Refer to Detail 2 on Sheet C5.5 for flow rates.

The bid quantity for CLIN 8 New HDPE Canal Liner is 6,276 SY. For the bid quantity to be correct, the 1,600 LF long line would need to be 35 LF wide which it is not. Our takeoff is approximately double the bid quantity at nearly 12,000 SY.

The bid quantity has been revised to 10,225 SY.

See revised bid schedule.

Please review and update the CLIN 8 quantity in the bid schedule.

Refer updated CLIN 8 quantities in Revised Bid Schedule

Please clarify the pay limits of the liner and how the pay quantity will be measured and if the anchor trench portion is also measured and paid.

The quantity of material included in the anchor trench will be paid by SY installed (includes the vertical section).

The bid quantity for CLIN 7 Dredging is 4,594 CY and it also appears to be off by a factor of atleast two or three times. The area of canal excavation from the removal plans totals roughly 2.5 acres and for the bid quantity to be correct, the average depth of excavation would need to be approximately 14”. It appears from the cross sections the average depth of excavations range from 2 feet to 5 feet in the canal. Additionally, the removal plans and cross sections do not align. On the east, the removal plans do not show excavation beyond towpath Sta. 1+42 whereas the cross sections show excavation to Sta. -1+00. On the west side, the removal plans indicate excavation extending approximately 600 feet beyond Sta. 17+00 that is provided in the cross sections.

The bid quantity has been revised as follows:

10,410 CY of dredging for the installation of the Canal Liner (Base Bid) and 2,116 CY of dredging outside of the liner footprint (Bid Option). Plan view on Sheet C3.4 has been updated and sections included on Sheet C13 series.

Please provide cross sections for these missing areas and clarify if there is some portion of the canal excavation that is not paid or incidental.

Plan view on Sheet C3.4 has been updated and sections included on Sheet C13 series.

The cross sections also do not match the detail of the liner profile. Please clarify if the excavation for the gravel, sand, underdrains, and anchor trenches are paid under dredging.

Due to the scale of the sections, the small details of the liner could not be illustrated legibly. Refer to construction details for detailed information, and also Refer to Section 01 27 00 Definition of Contract Line Items, CLIN 10.

Please review and update the CLIN 7 quantity in the bid schedule.

The bid quantity in CLIN 7 has been revised to 10,410 CY for dredging within the footprint of the canal liner (Base Bid) and 2,116 CY under CLIN 21 (Bid Option) for dredging outside the footprint of the Canal Liner .

Notes on Sheet S1.0 state the following:

Rechinking of entire stone wall per details on S1.1 and project specifications. Then it states, assume 15% of wall surface requires rechinking. These seem to be contradictory statements. The Bid Quantity schedule for CLIN 9 is 3,170 SF which is in line with 15% of wall surface area. Upon wall inspection on site, the majority of joints on wall have a width of 2” or greater at some point. Will the CLIN 9 quantity be revised to reflect the site condition?

Refer to revised Bid Schedule. CLIN 9 revised in the Base Bid to CLIN 11 and Bid Options added.

Please confirm if the IGE Estimated Price Range is still accurate once the quantities are revised for CLIN’s 7, 8 and 9.

Refer to revised Bid Schedule for Base Bids and Bid Options. No magnitude of construction value changes are necessary.

Please clarify the contract duration as two SF 1442’s were issued with different durations. Also, we request the contract duration be increased due to the increased quantities of CLIN 7, 8 and 9. This work is very sequenced per C5.1 and also has to work around the canal in stream water restriction from March 1 – June 15. This means the bulk of the work (canal and liner) has to wait until mid-June 2023 to start.

The correct period of performance is 365 calendar days.

Does the March 1-June 15 in water restriction apply to the three tributaries and access across the canal?

Reference Section 312319 Paragraph 1.5 & Section312500 Paragraph 3.3. NPS has confirmed with MDE & MD-DNR that the in-water restriction does apply to the three tributaries and the canal prism. NPS has confirmed that if the perimeter controls (i.e. cofferdams) are established prior to March 1, they can remain in-place and work can continue within them.

For the Historic Stone Wall, please confirm that new wall caps can be made in multiple pieces as they are on existing wall.

Full depth wall capstones are required for reconstructed walls as required by contract - See Section 0442300 Paragraph 1.3.A1.h.

Please confirm that all new stone supplied for project is to come from Tri-State Quarries (This is the only active quarry at the moment).

Butressing stone shall consist of field stone or quarry stone made up of durable, hard and strong that it will not disintegrate on exposure to water or weathering. The specific gravity of the individual stones shall be at least 2.5. and has a density of at least 150 pounds per cubic foot. To minimize the impact to the historic landscape, the Class III Riprap Buttress Armament stone shall be similar in color and character to match existing - See Section 312000 Paragraph 2.1.O. To minimize the impact to the historic landscape, color of stone used for stream restoration is required to be similar in color and character to match existing within 50-linear feet (assumed viewshed) of the edge of canal - See Section 313300 Paragraph 2.1.D and/or See Section 312200 Paragraph 2.3.

Wall stones are described in Section 044300.

Please clarify if the Class 3 Rip Rap Armament and the boulders for the step pools are required to be produced from Tri- State Quarries (Mica Schist) or if different quarries that produce granite (grey) and limestone (white) are acceptable.

Butressing stone shall consist of field stone or quarry stone made up of durable, hard and strong that it will not disintegrate on exposure to water or weathering. The specific gravity of the individual stones shall be at least 2.5. and has a density of at least 150 pounds per cubic foot. To minimize the impact to the historic landscape, the Class III Riprap Buttress Armament stone shall be similar in color and character to match existing - See Section 312000 Paragraph 2.1.O. To minimize the impact to the historic landscape, color of stone used for stream restoration is required to be similar in color and character to match existing within 50-linear feet (assumed viewshed) of the edge of canal - See Section 313300 Paragraph 2.1.D and/or See Section 312200 Paragraph 2.3.

The match lines do not appear to match up on the plans. Please review. They appear to be reducing the area of work.

The "Match Line" shown in the planviews are not "matching" lines, but rather indicate the limits of the view ports which overlap.

Please confirm the pay quantity for CLIN 10 includes payment for both the excavation of existing material and embankment of the buttress material.

CLIN 10 re-numbered to CLIN 12 in the revised bid Schedule and has been revised for more clarity

CLIN 11 for the rip rap armament is 1,750 CY. Specification 01 27 00, 3.1.K says this items is paid by the ton. Please clarify.

CLIN 11 re-numbered to CLIN 13. Unit of measure revised to CY instead of tons.

The summary of work, specification 01 11 00, 1.6.I, describes additional hauling restrictions for Washington Aqueduct and DC Water’s Potomac Interceptor.

See Sheets G2 and C2.

Please provide these specific hauling restrictions or direct us to where they are listed in the documents.

See Sheets G2 and C2.

Also, please explain the restrictions related to the “Zone of Influence” that is listed on the plan sheets.

See Potomac Interceptor Notes on Sheet G2.

Is the temporary matting shown on sheet 14 for a wetland area or for the Interceptor?

Temporary matting is for the wetland area.

Sheet 23 of 79 has a detail for the temporary matting and says that they are required for any work within the canal. Does this apply for the canal area behind the stone wall or the entire canal? Also, does it apply during the instream restriction or at all times?

Temporary matting is required for access in the streams and weltands to protect existing natural resources. Within the canal limits of dredging contractor can access using their means and methods (which may include timber matting but is not prescribed or required by NPS). Reference Section 312319 Paragraph 1.5 & Section312500 Paragraph 3.3. NPS has confirmed with MDE & MD-DNR that the in-water restriction does apply to the three tributaries and the canal prism. NPS has confirmed that if the perimeter controls (i.e.

cofferdams) are established prior to March 1, they can remain in-place and work can continue within them.

Sheet C2, Hauling Note 2 says Macarthur Blvd is restricted to vehicles over 4 wheels or 6 tons gross weight except by permit.

Please confirm permits will be issued for this project so that industry standard dump trucks can deliver aggregates to the jobsite and haul away spoils without reduced loads.

NPS confirmed with MCDOT and USACE Washington Aqueduct that Brickyard Road can be used for hauling access to the Washington Aqueduct-Waterline Crossing at the intersection of Brickyard Road and MacArthur Blvd. Hauling equipment over the Washington Aqueduct- Waterline Crossing and DC Water Potomac Interceptor is required to not exceed AASHTO H- 20 requirements. Any trucking over the infrastructure along MacArthur Blvd and Clara Barton Parkway is required to be permitted (as identified in Sheet G2 and C2). Towpath load restrictions at the historic culvert 15 and carderock road culvert have been clarified in Sheet G2.

We read the documents that it is acceptable to drive pickups trucks on the towpath without matting. Please allow the equivalent pickup truck loading to be applied instead of the 240-250 ?

Contractor shall select and locate equipment relative to the backside of the existing wall, such that the equipment maintains an equivalent surcharge less than 240psf on the wall. For example, a 2-axle vehicle located at least 2 feet from the backside of the wall may have a maximum axle weight of 18,000 lbs.

PSF that is listed throughout the documents within the 1,000 LF stone wall section.

Reducing the load to 250 PSF is far less than a pickup truck (2,500-3,000 PSF) and is going to add significant cost to the project.

Contractor shall select and locate equipment relative to the backside of the existing wall, such that the equipment maintains an equivalent surcharge less than 240psf on the wall. For example, a 2-axle vehicle located at least 2 feet from the backside of the wall may have a maximum axle weight of 18,000 lbs.

Specification 312000 describes a cohesive material for the 12” of canal backfill that is placed on top of the HDPE liner. Please provide the compaction requirement for this material. Within the 1,000 LF long area behind the stone wall that has the loading restriction, should this not be designed to a different specification that does not require compaction? Mats are unable to be used with the final compaction equipment and the other notes disallow any vibration within 35 of the wall. Please provide this alternate backfill material option.

Refer to Revised Spec Section 31 20 00 for liner fill and compaction requirements. The Park is open to alternative backfill options as long as it meets the design intent.

Sheet C7.4, detail 3 states we are to compact the existing subgrade for the canal to 95%. Please remove this requirement or change the loading and vibration requirement to permit compaction of the existing canal subgrade.

Compact to 90% as observed in ASTM D 698 using a static roller with a minimum contact pressure of 65 psi.

The cross sections provide a 100 year WSE for the Potomac River of approximately 95.5.

Can you please provide the Normal WSE and 10 year WSE for the Potomac in the area of the stone wall?

WSE at time of topographic survey, signified by edge of water - upstream of project area is 58.0, and downstream is 57.3. WSE vary. The calculated proposed WSEL for 10 year is approxinately 65.09.

Most of the buttress work is below the 100 year flood elevation and we need to excavate anywhere from 4’ to 7’ of material from the front face of the wall for the buttress/riprap. Specification 31 20 00 section 3.13.B says we need to “place uniform lifts across the full length of each buttress layer.” Please confirm we can work NPS to develop a plan to build this work in sections so that a 250’ long section of the historic stone wall is not exposed to flooding for long periods of time.

The construction of work in sections, to mitigate risk to the contractor, is considered to be allowable as contractor's means & methods.

Why does C13.2 show only a 6’ wide road instead of the 12’ on prior sheets? Please confirm we can work with NPS post-award to construct access roads the make the project constructible and cost effective.

There is a temporary 6' wide access road for the eastern buttressing (see sheet C4.4). The 12' wide temporary access road is for the western buttressing. Alternate methods can be proposed by the contractor for NPS approval after award, with the goal to limit disturbance to the existing landscape.

Where will the Contracting Officers Field Office described in 01 50 00, 2.2.B, be located?

Parking Lot B, Refer to Sheet C2.

Please confirm there is no seeding in the canal when finished.

Confirmed.

46 Please confirm no LOD fencing is required.

Confirmed. However, contractor is responsible for site security and pedestrian control which may necessitate fencing some areas.

Please confirm we are to assume the excavated material is not contaminated.

See the Geotechnical Report p.11 according to which analytical results for all four samples are below the MDE's Category 1 screening levels.

Specification 31 20 00 section 3.4 describes both Unclassified Excavation and Classified Excavation. Please confirm we are not to be performing rock excavation if encountered in the buttress, canal, or streams.

Confirmed

Specification 31 50 00 Excavation Support and Protection is listed on the Table of Contents (page 3 of 238) but not included.

Please provide if applicable.

Disreguard previous specifications and replace with the attached specifications.

The E&S Plan shows the 24” Clean Water Diversion Pipes for Streams #1 and #2 discharging within the excavation limits which would appear to create a ponding condition in the work area.

Refer to Revised Sheet C4.4A. Altered outlet locations.

Shouldn’t the E&S Plans extend these lines to show them discharging at or near the western temporary causeway? Also, the quantities of the 24” clean water pipes shown on C5.5 do not match what is shown on the plans.

Refer to revised Sheets C4.4A and C5.5A.

Should the E&S drawings be phased so that the canal area west of the liner can be excavated earlier in the project?

Contractor may choose to adjust work phases as approved by the CO & MDE.

It appears the E&S plans only address water flowing into the work zone from the three streams. The entire work zone is downstream of a hill and will experience water flow in areas outside of these three streams. It would seem additional measures such as berms will be required to manage this water. Please review and clarify.

Removable pumping will pump any offsite runoff entering the canal/work area. No berms or additional disturbance to redirect runoff is part of the permitted work but may be provided by the contractor as part of their means and methods of managing the site and dewatering.

The geotechnical report states the canal was drained in 2016. On June 3, 2022 the canal was holding a significant amount of water (primarily to the west) and did not appear to be flowing in any direction. Is this typical for water to be constantly sitting in the canal?

The water surface elevation in the canal vary. In 2016, the canal water surface elevations were "lowered" using existing upstream wasteweir at widewater (mile marker 13), using the wasteweir downstream at mile marker 9.67, and opening the paddle gates at Lock 14 (mile marker 9.47).

Residual flow from the adjacent tributaries drains into the canal and result in impounded water held back by intermittent sediment shoals between the site and these canal water control features. The water surface elevations seen during the solicitation are representative of the extent of "lowered" water conditions.

56 How was the canal drained in 2016?

The water surface elevation in the canal vary. In 2016, the canal water surface elevations were "lowered" using existing upstream wasteweir at widewater (mile marker 13), using the wasteweir downstream at mile marker 9.67, and opening the paddle gates at Lock 14 (mile marker 9.47).

Residual flow from the adjacent tributaries drains into the canal and result in impounded water held back by intermittent sediment shoals between the site and these canal water control features. The water surface elevations seen during the solicitation are representative of the extent of "lowered" water conditions.

Are any additional permits required by the Contractor beyond the NPDES General Stormwater Permit and MDBR General Permit?

Contractor is required to obtain permits for truck/equipment for hauling/access on roadways.

See Paragraph 1.9 - Section 013100 regarding contractor's responsibility to provide any other permits required to perform the work.

We request the bid date be extended in order to allow more time to get all questions addressed. It seems like there are too many large open items for a June 20th due date. A due date of July 1st or later would seem more realistic.

Proposal Final Due Date is 2 PM Mountain Time Thursday July 28, 2022

Please clarify is the bid is due at 2PM or 4PM Eastern Time.

Proposal Due Time is 2 PM Mountain

We request the bid date be moved to the week of July 4th to provide enough time to review all of the Q&A responses and incorporate those responses into our estimate and proposal.

Proposal Final Due Date is 2 PM Mountain Time Thursday July 28, 2022

Please confirm the contract duration if to achieve substantial completion and that punchlist will take place after substantial.

Confirmed.

Should we assume the causeway will not overtop if built in accordance with the design provided?

Refer to revised Tempoorary Cofferdam Causeway Crossing on Sheet C5.8A

Can you please provide any historical water elevation data or further explanation within this section of the canal (i.e. seasonal changes, storm events, etc)?

No historical water elevation data is available from NPS. The water surface elevation in the canal vary.

In 2016, the canal water surface elevations were "lowered" using existing upstream wasteweir at widewater (mile marker 13), using the wasteweir downstream at mile marker 9.67, and opening the paddle gates at Lock 14 (mile marker 9.47).

Residual flow from the adjacent tributaries drains into the canal and result in impounded water held back by intermittent sediment shoals between the site and these canal water control features. The water surface elevations seen during the solicitation are representative of the extent of "lowered" water conditions.

Please confirm if the owner will accept completed canal sections as we proceed (with as-built surveys provided) and the contractor is not responsible to return to areas in the event sediment occurs due to rain events.

See definitions of CLINs, payment is based on surveyed quantities. If survey data is collected and government can confirm contract grades are met prior to storm, contractor can work with contract staff to determine options following subsequent sedimentation driven by storms.

Does Detail 1 on C7.1 indicate 2 PVC liners?

What is the black line below the 12” clay and does it remain in place?

This is the bottom of the existing clay liner.

Removal shall be to the extents indicated in cross sections and details. This detail provided for informational purposes and likely varies.

Please provide additional information on the 84” Potomac Interceptor:

a.What type of pipe is the 84” sewer line?

b.Some details in the plans show a concrete cap on the 84” and some do not.

Please clarify if a concrete cap or encasement exists and how thick it is.

c.Is a pre and post video of the 84” line required? Note F.1. on Sheet G2 makes reference to it.

A. Reinforced Concrete Pipe.

B. Concrete cap is assumed to exist only over the sewer line within the limits of the existing liner.

C. NPS clarified with DCWATER in regards to the standard requirements from that agency included on Sheet G2. Per DCWATER, Detailed pre- and post-construction surveys of the utilities and structures utilizing in-line methods (i.e. video inspection, sewer TV, combination TV and Sonar, etc.) is not required.

Does the 250 PSF loading restriction still apply once the stone wall has been rechinked and buttress/Class 3 rip rap installed?

Contractor shall select and locate equipment relative to the backside of the existing wall, such that the equipment maintains an equivalent surcharge less than 240psf on the wall. For example, a 2-axle vehicle located at least 2 feet from the backside of the wall may have a maximum axle weight of 18,000 lbs.

Will we be paid under CLIN 4 and 5 for any trees removed for the Optional Stream Work in CLINs 13, 14 and 15? It appears that is what the quantities on CLIN 4 and 5 represent.

CLINs have been revised to remove the trees that were previously included erroneously in CLIN 4 and 5. All trees needed to be removed for the options should be included in the Optional CLINs.

Is natural sand required or will manufactured sand be acceptable for underneath the liner?

Needs to be natural sand without sharp angular corners.

Will we be required to remove access roads and matting that is in the canal for the March 1 – June 15 stream restriction? If so, the construction duration certainly needs to be increased.

Reference Section 312319 Paragraph 1.5 & Section312500 Paragraph 3.3. NPS has confirmed with MDE & MD-DNR that the in-water restriction does apply to the three tributaries and the canal prism. NPS has confirmed that if the perimeter controls (i.e. cofferdams) are established prior to March 1, they can remain in-place and work can continue within them.

Overall, we have prepared a preliminary schedule and it appears very aggressive due to the sequence of work in the plans, all of the temporary access/detours, duration of the stone wall repairs, and stream restrictions. We request NPS consider a more realistic approach for this project is to have the towpath open for Spring 2024 or roughly 550 days.

The correct period of performance is 365 calendar days.

Was any rock testing performed and can a strength in PSI be provided (#4 dowel drilling)?

No rock testing was done.

Is it acceptable to include 11x17 size sheets in our Technical Proposal?

Only electronic submissions are required, 11x17 is acceptable for large charts (schedules, etc.) not for text/narratives.

Please clarify what monitoring of the stone wall the contractor is required to perform during construction. Sheet S1.4 states to follow the contract documents, but we did not find this in the specifications.

Contractor required to survey/monitor existing prism locations as shown on sheets S0.1, S1.4 and C14.1

It appears all boring were taken within the towpath area and the Sediment Samples in Figure 3 of the Geotechnical Report may not have been taken from the canal where the dredging occurs. Can you please provide any additional information on the dredged material/canal sediment that needs to be removed?

a.Were samples taken from the canal area that is going to be dredged? If so, please provide information such as depths, location, and any photographs.

b.From visiting the site and doing some probing, it appears this material is unsuitable for re-use on the project. However, Section

2.4 of the Geotechnical Report indicates that some of this material can be used for fill in the buttress area. Can you please clarify this statement?

Sediment sample locations are shown in Figure 3 of the Geotechnical Report. Grain size distribution of the samples are in Table 4.

a) All samples were taken from approximate mid-part of the canal, and after logging and describing the sediments, bulks samples were taken for testing. b) Sample S1 from the canal is sand and gravel mix and may potentially be used as a portion of backfill as long as it meets the specification requirements. For bidding purposes assume all new material.

Are there any time restrictions for the streams?

Reference Section 312319 Paragraph 1.5 & Section312500 Paragraph 3.3. NPS has confirmed with MDE & MD-DNR that the in-water restriction does apply to the three tributaries and the canal prism. NPS has confirmed that if the perimeter controls (i.e. cofferdams) are established prior to March 1, they can remain in-place and work can continue within them.

Are there any permits from Maryland that apply to this project?

See Paragraph 1.9 - Section 013100 regarding contractor's responsibility to provide any other permits required to perform the work.

Please confirm that the installation of soldier piles and rock anchors as shown in the Geotechnical Report is not included.

Installation of soldier piles and rock anchors is not part of the scope. See plans and specifications for current scope.

Section 31 22 00 - 2.4 C. (Rock materials shall be hard, durable rock, resistant to weathering and water action, and free from overburden, spoil, shale, slate and organic material. Sandstone, or other sedimentary rock materials shall not be utilized as a component of Channel Bed Sand and Gravel.) Will quarried MD state approved limestone be allowed?

If it meets the specification limits that the limestone is hard, durable rock, resistant to weathering and water action, and free from overburden, spoil, shale, slate and organic material. with a minimum density of 150 pcf. However, To minimize the impact to the historic landscape, the Class III Riprap Buttress Armament stone shall be similar in color and character to match existing - See Section 312000 Paragraph 2.1.O. To minimize the impact to the historic landscape, color of stone used for stream restoration is required to be similar in color and character to match existing within 50-linear feet (assumed viewshed) of the edge of canal - See Section 313300 Paragraph 2.1.D and/or See Section 312200 Paragraph 2.3.

Section 31 33 00 – 2.1.H (The Contractor will locate potential sources for the rocks.

The Contractor and CO will jointly visit the site/quarry to determine whether the rock meets the specified requirements.

Contractor will not be granted an extension of time or extra compensation due to delay caused by sampling, testing, approval or disapproval of boulder materials under the requirements of these specifications. Will the park service provide more precise specifications for the imbricated boulders than those provided in 2.1 of this section?

These specifications appear to be adequate, no further details are anticipated to be provided at this time.

Will locally quarried limestone used in similar projects for MD State and WSSC stream restoration be permitted?

If it meets the specification limits that the limestone is hard, durable rock, resistant to weathering and water action, and free from overburden, spoil, shale, slate and organic material. with a minimum density of 150 pcf. However,To minimize the impact to the historic landscape, the Class III Riprap Buttress Armament stone shall be similar in color and character to match existing - See Section 312000 Paragraph 2.1.O. To minimize the impact to the historic landscape, color of stone used for stream restoration is required to be similar in color and character to match existing within 50-linear feet (assumed viewshed) of the edge of canal - See Section 313300 Paragraph 2.1.D and/or See Section 312200 Paragraph 2.3.

Will invasive plant eradication be part of this project?

See project plans and specifications for scope of work.

Are there any provisions for the life existing in the canal and the streams?

See Section 015723 of the Specifications.

SUPPLEMENTAL FINAL QUESTIONS

Due to the technical nature of this project, the small business goal of 30% of the total contract value is likely unachievable. We intend on using every small business willing to perform the work required in this contract, but many are unwilling to take risks associated with this project. Please consider lowering the goal to 10% of the total project value.

The 30% Goal is established in the basis of this Solicitation. Detail difference from that in the Small Business Plan if you are including one.

When will the questions and answers be posted? Is the bid date going to remain 7/14? We will need adequate time to react to Q&A.

Questions and Answers are being posted as soon as they can be secured. The Current Final Due Date is 2:00 PM Mountain Time July 28, 2022.

On Sheet G2, in the Access and Weight Restriction Notes, Note 4 identifies an existing engineered “land bridge”. The plans further explain that it’s located near the intersection of Brickyard Road and Clara Barton Parkway, however, those two roadways don’t intersect. Please clarify the location. Please clarify the capacity of this structure. Please provide photos of this location.

The Land Bridge is a concrete structure that protects the Washington Aqueduct Water Lines located at the intersection of Brickyard Road and MacArthur Blvd. It is identified as "Washington Aqueduct-Waterline Crossing" on Sheet C2.

Weight limits for the water intakes (aqueduct) and potomac interceptor crossing are identified in the access and weight restriction notes on Sheet G2 (equal to or less than AASHTO H-20). Any trucking over the infrastructure along MacArthur Blvd and Clara Barton Parkway is required to be permitted (as identified in Sheet G2 and C2). The site is open to the public and the Contractor may photograph the land bridge if necessary.

Please provide suggested haul routes for loaded commercial vehicles.

Per Section 011100 Paragraph 1.6.I of the Specifications, Hauling routes are a responsibility of the contractor. NPS confirmed with MCDOT and USACE Washington Aqueduct that Brickyard Road can be used for hauling access to the Washington Aqueduct-Waterline Crossing at the intersection of Brickyard Road and MacArthur Blvd. Hauling equipment over the Washington Aqueduct- Waterline Crossing and DC Water Potomac Interceptor is required to not exceed AASHTO H- 20 requirements. Any trucking over the infrastructure along MacArthur Blvd and Clara Barton Parkway is required to be permitted (as identified in Sheet G2 and C2). Towpath load restrictions at the historic culvert 15 and carderock road culvert have been clarified in Sheet G2.

Has NPS coordinated with Montgomery County, GWMP, and USACE on the contractor’s use of the surrounding roads with hauling restrictions? This early coordination and pre-planning are essential to the project as it will not be possible to move forward with this project without them.

NPS confirmed with MCDOT and USACE Washington Aqueduct that Brickyard Road can be used for hauling access to the Washington Aqueduct-Waterline Crossing at the intersection of Brickyard Road and MacArthur Blvd. Hauling equipment over the Washington Aqueduct- Waterline Crossing and DC Water Potomac Interceptor is required to not exceed AASHTO H- 20 requirements. Any trucking over the infrastructure along MacArthur Blvd and Clara Barton Parkway is required to be permitted (as identified in Sheet G2 and C2). Towpath load restrictions at the historic culvert 15 and carderock road culvert have been clarified in Sheet G2.

Commercial vehicle travel on Clara Barton Parkway and MacArthur Boulevard is critical to the success of this project. Please confirm that the contractor will be allowed to travel on these roads with loaded commercial vehicles.

NPS has coordinated with both entities responsible for regulating loads on MacArthur Blvd and Clara Barton Parkway. They have been identified on sheet C2 and G2 so that the contractor may confirm any hauling restrictions with them at this time, as well as after award. NPS is not responsible for coordinating haul routes and loads used by the contractor with other entities since they are within the purview of the contractor's "means and methods".

On Sam.Gov, the document “Sol_140P2022R0107.pdf” posted on May 20, 2022, has 270 calendar days in box 11.

But another document, “B08_Solit_140P2022R0107.pdf,” also posted on May 20, 2022, has 365 days in box 11. Please confirm which is correct.

365 Calendar Days is the correct Contract Period of Performance.

Section 5/C7.4 indicates a ¼” continuous closed-cell neoprene rubber; what is the width of this item?

Neoprene rubber shall be 2” wide.

Due to the upcoming holiday and not receiving responses to our questions thus far, please extend the bid date to 7/15/22 so we may address the answers/changes in our technical proposal with adequate time.

The Current Final Due Date is 2:00 PM Mountain Time July 28, 2022.

We are concerned with equipment access within the canal due to the poor soil conditions indicated in the bidding documents. The current observed conditions and limited access points into the canal will lead to grading equipment getting sucked in the quicksand-like material. This is an extreme risk, and the means and methods to avoid this are incredibly costly. Are there any boring locations that provide penetration resistance within the canal proper, not on the towpath? Would the government consider extending the LOD on the north side of the canal to allow the contractor to access the canal from multiple access points?

There is no borehole data within the canal limits with Standard Penetration Testing (SPT) to provide compactness/consistency. Geotechnical Report has been provided to bidders which includes results of limited sediment sampling in the canal.

Within the canal limits of dredging contractor can access using their means and methods (which may include timber matting but is not prescribed or required by NPS). See Detail 1/C5.6. The contractor is responsible to determine the final means and methods.

The 12’ and 6’ temporary access roads are shown on sheets C4.2, C4.3, and C13.8 are identified to receive a large amount of stone fill for contractor access. Please confirm that this fill material is to remain after construction.

The 12' & 6' wide tempoary access roads are shown as "temporary" and are to be removed at the conclusion of their use in this construction project. The use of timber mats and avoidance of excavation below existing grade between Station 6+34 to 13+15 on the 12' temporary access road has been clarified on sheet C4.2 and profiles on sheet C13.9. This is required to mitigate impacts to existing rare plants and avoid permanent impact to the cultural landscape. Similarly, the temporary 6' access road at the downstream end of the project is fill only to avoid impacts to the cultural landscape. The intent of Detail 4/C5.6 is to include a separation fabric beneath any of the temporary stone access roads to facilitate easier removal at construction completion. If minor refinements to access paths are proposed by the contractor to reflect more efficient means and methods of performing the work they can be considered by NPS and MDE. Any minor refinements should further minimize disturbance to existing natural resources and should not result in further ground disturbances than shown in the plans.

Sheet C4.1 shows a Temporary Rock Outlet Protection on the ‘wet’ side of the temporary causeway cofferdam; please confirm that the contractor will build a Temporary Rock Outlet Protection underwater.

The intent of the applied detail is to prevent erosion at the outfall of the removable pumping station that meets MDE Standards for Erosion and Sediment Control. One method to accomplish this is via installing the temporary rock outlet protection, which can be installed using the means and methods defined by the contractor and final location as shown or refined in the field in the general vicinity (and within existing LOD) to accomplish it's intended purpose. If the contractor develops an alternate method for preventing erosion at the outfall of the removable pumping station that meets MDE Standards for Erosion and Sediment Control it can be proposed for consideration by MDE and NPS COR.

What is the current maximum depth of water in the canal?

The water surface elevation in the canal vary. In 2016, the canal water surface elevations were "lowered" using existing upstream wasteweir at Widewater (mile marker 13), using the wasteweir downstream at mile marker 9.67, and opening the paddle gates at Lock 14 (mile marker 9.47).

Residual flow from the adjacent tributaries drains into the canal and result in impounded water held back by intermittent sediment shoals between the site and these canal water control features. The water surface elevations seen during the solicitation are representative of the extent of "lowered" water conditions. The site is open to the public and the contractor is encouraged to collect any field observations necessary to finalize their bids.

Section 31 23 19 Dewatering: 1.5 Work Restrictions states instream work is prohibited from March 1st through June 15th. The contractor will need to work in the stream during this time; please confirm that MDE will provide an exemption for this project. It will not be possible to complete the work in the allotted timeframe without an exemption or time extension.

Reference Section 312319 Paragraph 1.5 & Section312500 Paragraph 3.3. NPS has confirmed with MDE & MD-DNR that the in-water restriction does apply to the three tributaries and the canal prism. NPS has confirmed that if the perimeter controls (i.e. cofferdams) are established prior to March 1, they can remain in-place and work can continue within them.

The liner manufacturers we have been contacting will not provide a 25-year warranty. They would do eight years, which will be industry-standard for liner manufacturers. The specs call for 25 yrs.

Please modify the specifications accordingly or provide a contact to a manufacturer that will offer a 25-year warranty.

NPS confirmed that multiple providers are capable of offering a 20-year warranty for liner systems in buried applications. The requirement for the contract has been revised to require a minimum 20-year warranty for the liner system (revised specifications will be provided at a later date).