Murphy Dam Outlet Works Improvements Project, Pittsburg, NH

ADDENDUM NO. 7

To: All Prospective Bidders Murphy Dam Outlet Works Improvements Project

Location: Pittsburg, NH

From: Charlie Krautmann – NHDES Dam Bureau Josh Paquet – GFT

Re: Addendum No. 7

Date: June 19th, 2026

Please find the following ADDENDUM NO. 7 for the Murphy Dam Outlet Works Improvements Project which is to be included as part of the Contract Documents thereof.

As per Specification Section 00200, Article 13.09 the bid shall contain an acknowledgment of receipt of this Addendum No. 7, (and all addenda). The addendum number and date shall be entered in the space provided in Section 00301 – Bid Form, Article 3 – 3.01A

Please note bids are due Friday, June 26th, 2026 at 1300 (EST). Hard copy bids may be received as stipulated in the Contract Documents.

This Addendum has been issued to include clarifications to a few questions which include:

Item #1 – Clarification

Question – Are the concrete walls, ceiling, and floor of the annular space around the new penstocks, currently coated or with some type of finish? Do they need any type of blasting or preparation before placing new concrete? Will a simple power wash be sufficient? If there are any coatings, have these been tested for lead, asbestos, or other hazmat?

Response – The existing concrete surface does not need to be mechanically prepared prior to placing the annular concrete. A simple power wash will be sufficient to remove any existing debris or contaminants at the joint location.

The concrete is not believed to exhibit any coatings. Any structure that may exhibit a coating have not been tested for the presence of lead, asbestos or hazmat specific materials.

Item #2 – Clarification

Question – What is the intent of the non-shrink grout bid item? Where is this to be used?

Response – Bid Item 01200-9e, “Concrete Construction – Non-shrink Grout for Equipment Bases and Anchors,” is intended for non-shrink grout required at equipment bases, base plates, anchor pockets, leveling pads, and similar localized equipment or anchorage installations where indicated by the Contract Documents or required by the approved equipment submittals.

Item #3 – Clarification

Question – Detail 1 on S-2 is not fully clear:

• Are we installing bolts to attach the new flange to the existing valve flange? If so, are the existing holes in the dow-valve flange already threaded, and we can just bolt in to these?

Do the bolt holes need to be tapped or re-threaded? It seems that there's no access to back of the valve flange to install through bolts.

• The detail shows a 3/8 weld on the exterior of penstock to the slip-on hub flange, but on the interior is not clear that it needs to be welded, as it only says to be trimmed, but shows what it could be a weld? Please clarify.

• Are there any details or spec for the O-Ring? Can a gasket be used?

• Is there a specific preparation required for the face of the existing flange. Photos of the existing condition show it to be covered with some type of coating, corrosion, or algae.

Response – Intent is for the new flange to abut the existing flange with intimate contact. The extension pipe will be leveled and supported in place while an interior groove weld between the existing cast-steel flange, new pipe extension and new pipe collar is placed along the interior circumference. Then the annular concrete will ultimately support the pipe and act as an anchor for the new extension pipe. The contractor can choose based on means and methods to leverage a new slip on collar flange with corresponding holes to help align and secure the new pipe and collar temporarily in place. The contractor could also choose to utilize a proposed collar that does not have holes and is aligned and supported based on a different method.

The upstream flange seal shall be an O-ring seal seated in the O-ring gland shown on the detail.

The O-ring shall be EPDM and suitable for the specified service pressure. A gasket can be proposed as a substitution as a submittal to be approved by the Engineer.

Contractor shall clean and prepare the existing flange face to remove algae, debris, and other deleterious material. The existing flange face shall be inspected and machined, dressed, or otherwise restored as required to provide a suitable sealing surface for the O-ring. Contractor shall notify Engineer if flange deterioration, pitting, dimensional irregularity, or other conditions are encountered that prevent proper sealing.

Item #4 – Clarification

Question – We learned that the southern access road is normally used as a snowmobile trail during the winter months. Will be allowed to fully shutdown this trail for snowmobiles? Is the contractor responsible for plowing and sanding this road? Can the road be plowed?

Response – Snowmobile traffic may be rerouted, similar to ATVs, over the crest of the dam unless this reroute presents a safety issue. If a safety issue presents itself for either snowmobile or ATV traffic along the crest of the dam, the contractor will be required to work with the owner and the local snowmobile and ATV club to develop an alternative route. Should the contractor not require the use of southern access road during the winter or other periods then the southern access road will be used for snowmobile and ATV traffic. The contractor is responsible for maintaining the southern access road along the toe of the dam, including plowing, sanding, salting, or any combination of these activities as needed.

Item #5 – Clarification

Question – Are Murphy Dam Road or Cedar Stream road posted for heavy load traffic in the spring?

Response – Yes, both roads are typically posted for heavy load restrictions during the spring.

The contractor should must coordinate with the Town Road Agent to apply for a waiver if heavy loads are required during the posted period.

Item #6 – Clarification

Question – Is there more information about the broom gate engine that can be provided? What is the HP and RPM required?

Response – See Addendum 2, Attachment B. Sheet 41007 has text in the lower right that suggest power unit, standard rating HP at RPMs, hoist speed and lowering speed.

Item #7 – Clarification

Question – The jet flow gate valve specifications reference the drain of the conduit and the valve, both to receive a valve stem up to the operator deck, however, according to the drawing C-10, the conduit drain pipe and valves are not below the operator deck, can you clarify the intent of this scope, if these are required to have a stem into the operator deck, can you please provide a detail in the drawings?

Response – The conduit drain valve shall be installed within the stilling basin as shown on the Contract Drawings. The intent is not to extend the conduit drain valve stem to the operator deck.

The current Jet Flow Gate specification includes language requiring a valve stem extension, guides, and an operating handle at the operator deck for the conduit drain valve. This requirement conflicts with the configuration shown on the Drawings. The specification will be revised by addendum to remove the requirement for the conduit drain valve stem extension to the operator deck and to clarify that the conduit drain valve shall be located and installed as shown on the Drawings.

The Contractor shall furnish and install the conduit drain valve, piping, supports, fittings, and appurtenances required for a complete installation at the stilling basin location shown. Final routing, support, and connection details shall be coordinated with the approved Jet Flow Gate shop drawings.

Item #8 – Clarification

Question – Following the previous question, the specification of the valves calls for heat trace an insulation on the conduit drain pipe, the air valve, and drain valve. If I understand correctly, these will all be submerged underwater. Can you confirm if this is required, as it's not shown in any of the drawings. No electrical drawings provided for heat trace connections.

Response – Heat trace and insulation requirements apply only to small-diameter air-valve piping, conduit drain piping, and valve bodies that can retain water and are located above the normal water surface or otherwise exposed to freezing air.

Heat trace and insulation are not required on pipe or valve portions that are intended to remain submerged during normal operation or that are encased in concrete. Contractor and Jet Flow

Gate manufacturer shall identify the proposed limits of heat trace and insulation in the shop drawings.

Electrical connections for required heat trace shall be coordinated with the Jet Flow Gate controls and Division 16 electrical work and shall comply with NEC requirements.

Item #9 – Clarification

Question – The bid form and M&P reference multiple times installation and testing of HPU and hydraulic lines, is our understanding that the new gates are all electrically actuated and there shouldn't be any hydraulics. Please clarify.

Response – Confirmed. The new Jet Flow Gates shall be electrically actuated. Hydraulic power units, hydraulic lines, and hydraulic actuators are not required for the new Jet Flow Gates.

References in the Contract Documents to hydraulic operators, hydraulic power units, or hydraulic lines for the Jet Flow Gates shall be interpreted as references to the electric motor operators, actuators, controls, conduit, wiring, and appurtenances required for the electrically actuated Jet Flow Gates. Contract Documents will be revised by addendum to clarify this intent.

Item #10 – Clarification

Question – Per the M&P, there's seems to be overlap between the scope of Bid Item 3 and Bid Item 4. Please clarify what is to be included in each item, as all dewatering operations could fall under Bid Item 4.

Response – Bid Item 01200-3, Care and Diversion of Water, includes the Contractor’s overall means and methods for managing reservoir, penstock, outlet, and site water during construction, including temporary diversion, isolation of work areas, maintaining required releases, coordinating with Owner operations, and protecting the Work from reservoir, river, stormwater, and operational flows.

Bid Item 01200-4, Dewatering, includes removal and control of water from isolated work areas after diversion or isolation measures are in place. This includes pumping, sumps, hoses, temporary piping, seepage and leakage control, precipitation control within excavations or work areas, treatment and discharge of dewatering flows, and maintenance of dry working conditions necessary to perform the Work.

There shall be no duplicate payment between these items. Contractor shall allocate costs based on the primary purpose of the work being performed.

Item #11 – Clarification

Question – Seems like the scale on drawing C-8 and ES-1 is wrong. Shown as 1:10, when perhaps it should be 1:20. Can you please confirm?

Response – The intended full-size scale for Sheets C-8 and ES-1 is 1 inch = 20 feet. Graphic scales, dimensions, coordinates, and control points shall govern over scaled measurements. The drawings will be revised by addendum to clarify. No design geometry or quantity changes are associated with this clarification.

Murphy Dam Outlet Works Improvements Project, Pittsburg, NH