Attachment_5_Clarifications_1_-_4_0001.pdf

Conduct NTCRA under CERCLA at Hidden Hill mine Mojave NP Attachment 5: Clarifications

Attachment 5: Clarifications to Solicitation #140P2126Q0049

Project description: Conduct a removal action under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) to remove tailings and commingled soil from the Hidden Hill historic mine site in Mojave National Preserve.

Amendment 1 posted at SAM.gov on 4/21/26

Site visit was held on 4/9/26; the list of attendees is at the end of this document. It was convened by the NPS Regional Environmental Coordinator, who said “Welcome! Thank you all for your attendance at this site visit and your interest in this CERCLA response action at the Hidden Hill former mine site. I’m Gary Riley, Regional Environmental Engineer for the National Park Service, Pacific West Region. Sarah Welch is the Contracting Officer and source selection authority for this project, but couldn’t attend today. Jenny Phillippe, Geologist, National Park Service Washington Support Office will be the Contracting Officer’s Representative for this work, and she is also unable to attend today.

I hope you have had a chance to review the solicitation, specifications, and drawings. The purpose of today’s meeting is to show you the site and for you to become familiar with the logistics of working here. We do not intend to review the RFQ or specs and will take only limited verbal questions related to the site.

A few administrative details:

• Please register on the sign-in sheet and indicate if you are a potential prime or sub-contractor. You may also leave a business card.

• Please refrain from side conversations during the tour. We’d like everyone to hear the same information.

• There is no public restroom. Please practice ‘leave no trace’ if you use one of our natural restrooms.

• After this introduction, I will lead the group drive to the location and provide a walking tour of the site to show you points of interest related to this work. Then we’ll reconvene for limited questions and formally conclude the site visit. However, you’re welcome to remain onsite to look at any areas more closely, take measurements, etc. Ground disturbance is prohibited.

Reminders about the solicitation:

• Nothing said today changes the terms, conditions, requirements, or specifications of the solicitation and eventual contract. All changes will be formalized and incorporated by formal written amendment(s) to the RFQ, which the CO will post at SAM.gov.

• As previously mentioned, we will take only limited questions during this site visit.

Submit all questions to Sarah Welch, ideally referencing the particular section of the specs, figures, or RFQ. Questions received by 3:00 pm PT on Wednesday 4/15/26 will be answered in an amendment approximately a week later that will also include notes from this site visit and a list of attendees.

• I encourage you to thoroughly review Sections L and M of the solicitation, which describe the evaluation process, define the evaluation factors, and include detailed instructions about what to include in your quote and how to submit it.

• Quotes are currently due on Tuesday, May 5 at 3:00 pm PT unless extended by amendment.”

This document provides clarifications based on queries submitted after the site visit.

1) 5.9.1 states: Note that the Work Plan calls for recontouring with no backfilling of removed materials. Please confirm if the waste rock on the site may be used as a borrow source to backfill excavated areas, if needed.

a) The waste rock at the site may not be used as a borrow source. At this time, there are no plans to backfill the excavations. If during project execution, NPS decides that backfill needs to be brought in for the excavation areas, the Contracting Officer may negotiate a contract modification for import and placement of backfill from a borrow source within MOJA, in accordance with the NPS Contaminated Sites Clean Fill Protocol.

2) The SOW Section 2.4 states and Section 5.5.8.3 reiterates: Improvements to Hidden Hill Road to conduct the removal action are not permitted. Could minor improvements, such as 3” - 12" culverts, be temporarily installed and then removed to keep from damaging the road and vehicles?

a) Temporary installation of culverts will not be permitted. If other road minor modifications are proposed by the contractor (e.g. filling in small sections of the road with nearby rocks and material), then the specific locations and types of improvements shall be submitted to NPS for review and approval prior to initiating the repairs. The submittal must describe the road modification(s) and include methods to install and remove them, sketches, and other relevant details. If the COR and park POC concur with the road modifications proposed by the contractor, they will submit the documentation to the park for required compliance reviews that will take approximately 45 days.

3) The SOW states that: 5.5.8.1. MOJA does not have load, weight, or size limits that are more restrictive than the State or County laws. Hidden Hill Road is an unimproved dirt road requiring 4WD and high clearance and road improvements are explicitly prohibited. A fully loaded standard dump truck could weigh 50,000–66,000 lbs and would likely damage the two-lane road. Is there a weight limit for this road? Also, could the contractor use a small off-road articulated dump (e.g., Hydrema 707G), solely for the 4.8 trek to a staging area off Kelbaker Road (dirt road use only).

a) According to the Superintendent's Compendium, there are no MOJA-specific weight, load, or size limits for the dirt road beyond those imposed by State and County Laws. A small off-road articulated dump may be proposed for use on the dirt road only.

https://www.nps.gov/moja/learn/management/compendium.htm

NPS will not permit staging areas along South Kelbaker Road or staging areas that block public access to Hidden Hills Road.

The locations of proposed staging areas shall be included in the draft traffic control plan along with planned haul routes. If the contractor proposes a staging area outside the site, then the COR and park POC will review, tentatively accept/deny, and then submit for required compliance reviews, which will take approximately 45 days

4) The existing 9.2 Preservation of Historical Site Features - Site personnel will exercise care so as not to disturb existing structures and Site features. During the site walk, the rubble foundation wall was identified as a key concern because it abuts the tailings. Would the NPS consider adding language to require some sort of control, such as temporary buttressing or shoring, to protect the wall? If not, how close must the contractor excavate next to the wall?

a) No buttressing or shoring of the rubble wall is allowed. The contractor shall use hand tools near the rubble wall to excavate tailings to the maximum extent possible without damaging or undermining the structural integrity of the rubble wall.