Drawing record · Sheets SM-T35 and SM-THERM
Two chambers. One of them stays dry.
Trench 35 is a stacked vault. Power and data ride in the upper culvert. The heat lives in the sump below it. The surface void and the telecom mast are separate decisions.
It remains dry for the 250 kcmil three-phase backbone, fiber, and the pasteurization PEX, racked on Unistrut. Water belongs in the lower 7-foot sump.
Surface
Void, reservoir, and mast.
The reservoir volume below does not change with the diameter of the surface void. It is a 500-foot run of 7-foot pipe: about 143,872 gallons either way. The mast adds no gallons. It is a dry galvanized frame.
| Spec | 80 ft void | 200 ft void | LGS telecom tower |
|---|---|---|---|
| Logistics | WB-67 semi turnaround, one three-point pivot. 90° staging. | Continuous WB-67 path, 45° reverse staging for containers, dual-lane access. | Mesh backhaul and life-safety communications. |
| Role | Runoff detention, AASHTO turn geometry. | Regional large-volume hydrological control. Toroidal grid. | Commerce clean-energy / USDA REAP match. Resiliency anchor. |
| Reservoir | About 143,872 gallons. 500 ft × 7 ft diameter. | Same reservoir. The void diameter does not resize the pipe. | 0 gallons. Dry structure. |
| Material | CMP / HDPE culvert. | Modular 40 ft CMP/HDPE spans, or 40 ft container chassis. | Galvanized cold-formed steel, formed on site. |
Volume used on this desk: π × (3.5 ft)² × 500 ft × 7.4805 gallons, stated as 143,872 gallons.
Heat
The loop, in the open.
Raising the 143,872-gallon buffer from 50°F ground temperature to 140°F is about 108 million BTU. That is the charge. Holding the sump, and feeding the tunnel, is the operating load.
| Point | Figure used on this desk | Arithmetic |
|---|---|---|
| Mining rejection | 62 units | 1,130,000 BTU/hr into the hot loop |
| Reservoir | 143,872 gallons at 140°F (60°C) | 143,872 × 8.34 lb/gal × 90°F ≈ 108 million BTU from 50°F |
| Avocado tunnel | 2,000 sq ft, interior target 60°F | 85 BTU/sq ft/hr × 2,000 = 170,000 BTU/hr |
| Return | Exchanger on the 140°F loop | Chilled water goes back to the miners. The tunnel is a fraction of the rejection. |
Mast
A dry tower on the same books.
The telecommunications mast is framed in the same light-gauge steel as the poles. In the grant record it is not only an antenna stick. It is the life-safety communications and micro-grid anchor, tied back to the facility light poles and the Whidbey–Seattle–Peninsula mesh.
The frame, before antennas, sits in a range of $25,000–$45,000. The catalog lists one frame kit inside that range. Filing it does not award USDA REAP or Commerce funds.
