Sol_140G0122Q0107_Amd_0002.pdf

(x)

140G0122Q0107 x x

1 copies of the amendment; (b) By acknowledging receipt of this amendment on each copy of the offer submitted ; or (c) By separate letter or electronic communication which includes a reference to the solicitation and amendment numbers. FAILURE OF YOUR ACKNOWLEDGEMENT TO BE

RECEIVED AT THE PLACE DESIGNATED FOR THE RECEIPT OF OFFERS PRIOR TO THE HOUR AND DATE SPECIFIED MAY RESULT IN REJECTION OF YOUR

OFFER. If by virtue of this amendment you desire to change an offer already submitted , such change may be made by letter or electronic communication, provided each letter or electronic communication makes reference to the solicitation and this amendment, and is received prior to the opening hour and date specified.

x

GRB

RESTON VA 20192

12201 SUNRISE VALLEY DRIVE

205 NATIONAL CENTER

USGS OAG RESTON ACQUISITION BRANCH

04/21/20220002

13. THIS ITEM ONLY APPLIES TO MODIFICATION OF CONTRACTS/ORDERS. IT MODIFIES THE CONTRACT/ORDER NO. AS DESCRIBED IN ITEM 14.

12. ACCOUNTING AND APPROPRIATION DATA (If required) is not extended.is extended, Items 8 and 15, and returning

Offers must acknowledge receipt of this amendment prior to the hour and date specified in the solicitation or as amended , by one of the following methods: (a) By completing

The above numbered solicitation is amended as set forth in Item 14. The hour and date specified for receipt of Offers

11. THIS ITEM ONLY APPLIES TO AMENDMENTS OF SOLICITATIONS

FACILITY CODE CODE

10B. DATED (SEE ITEM 13)

10A. MODIFICATION OF CONTRACT/ORDER NO.

9B. DATED (SEE ITEM 11)

9A. AMENDMENT OF SOLICITATION NO.

CODE

8. NAME AND ADDRESS OF CONTRACTOR (No., street, county, State and ZIP Code)

7. ADMINISTERED BY (If other than Item 6)CODE 6. ISSUED BY

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4. REQUISITION/PURCHASE REQ. NO.3. EFFECTIVE DATE2. AMENDMENT/MODIFICATION NO. 5. PROJECT NO. (If applicable)

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AMENDMENT OF SOLICITATION/MODIFICATION OF CONTRACT

04/21/2022

CHECK ONE A. THIS CHANGE ORDER IS ISSUED PURSUANT TO: (Specify authority) THE CHANGES SET FORTH IN ITEM 14 ARE MADE IN THE CONTRACT

B. THE ABOVE NUMBERED CONTRACT/ORDER IS MODIFIED TO REFLECT THE ADMINISTRATIVE CHANGES (such as changes in paying office, C. THIS SUPPLEMENTAL AGREEMENT IS ENTERED INTO PURSUANT TO AUTHORITY OF:

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E. IMPORTANT: Contractor is not is required to sign this document and return __________________ copies to the issuing office.

ORDER NO. IN ITEM 10A.

14. DESCRIPTION OF AMENDMENT/MODIFICATION (Organized by UCF section headings, including solicitation/contract subject matter where feasible.)

Legacy Doc #: UGS

The purpose of this amendment is to provide response to questions, as follows:

1. Why do we specify a required size range from at least 0.1 to 500 microns, when clay and silt particles are generally less than 63 microns across and we sieve our samples through a

63 micron sieve?

There are three reasons for this. This is a pretty standard size range in the field to be able to fulfill (our current instrument that is a decade and a half old measures this size range), and was a good starting point in assessing what vendors are capable of delivering the type of results we're looking for. Furthermore, we would like to be able to in the

Continued ...

16A. NAME AND TITLE OF CONTRACTING OFFICER (Type or print)15A. NAME AND TITLE OF SIGNER (Type or print)

15C. DATE SIGNED 16B. UNITED STATES OF AMERICA 15B. CONTRACTOR/OFFEROR 16C. DATE SIGNED

(Signature of person authorized to sign) (Signature of Contracting Officer)

STANDARD FORM 30 (REV. 11/2016)

Prescribed by GSA FAR (48 CFR) 53.243

Previous edition unusable

Except as provided herein, all terms and conditions of the document referenced in Item 9 A or 10A, as heretofore changed, remains unchanged and in full force and effect .

ITEM NO. SUPPLIES/SERVICES QUANTITY UNIT UNIT PRICE AMOUNT

NAME OF OFFEROR OR CONTRACTOR

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140G0122Q0107/0002 future consider phasing out the need to sieve our samples to 63 microns, as this would allow us to save on labor costs. Sieving to a larger pore size, such as 2mm or 0.5mm, is much easier and takes less time. Finally, accidents happen in labs, and having the ability to detect particle sizes outside the range we're sieving to allows us to identify problems with our samples that might otherwise go unnoticed.

2. The desired size range is currently 0.1 to

5,000 microns with wet application. Would you revise your tender to open it up for dry dispersion for the coarser fraction?

While it is understood that 5,000 microns with wet application is a likely unrealistic high bar to clear, the desired size range is not a requirement, and vendors are encouraged to submit bids that don't fully satisfy this requirement.

As for dry dispersion, we are reluctant to include it as a possible alternative to wet dispersion for a few reasons. We frequently work with clay-heavy, fluvial sediments, and a chemical dispersant is required to get reliable results due to the strength of clay-silt bonds.

Our sieving process does not introduce a chemical dispersant (our lab uses Sodium

Hexametaphosphate, or SHMP) as that has the possibility to affect further chemical analyses other USGS labs run on our samples. Therefore, as part of our particle size analysis procedure, we introduce SHMP to a subsample of the now-sieved material to satisfy this condition. Changing this procedure to allow for dry dispersion would require an additional cycle of drying the sample, which would increase our lab costs. In the future, should we decide to sieve to a more lax pore size such as 0.5mm or 2mm, we would still likely add some type of chemical dispersant to ensure that we are breaking these clay-silt bonds and maintaining an accurate assessment of the particle size distribution. As such, while we are not wholy opposed to a dry dispersion particle size analyzer, it is less preferred, and must demonstrate an ability to chemically de-aggregate clay and silt peds without additional labor costs.

NSN 7540-01-152-8067 OPTIONAL FORM 336 (4-86)

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FAR (48 CFR) 53.110