Payap model v2: bigger factory, shared plant room, separate water treatment

User, October 2026: the factory is too small and needs room to grow
(possibly ten more Classics), one shared hydraulic and air supply, water
treatment perhaps in a separate building connected to the galvanics lab,
and a fully equipped workshop (maintenance tools, 3D printers, maybe a
lathe and a small CNC mill).

Model (rebuilt live in FreeCAD 26.3, BIM objects, Params-driven,
parametric check plot 135->145 m and factory 112->120 m passed):
- plot 135 m (11.4 rai) with a reserve; factory 112 x 25 m, 16 bays,
  82 m visitor corridor, fire wall at 90 m;
- press hall ~870 m2: two Duplex systems (EX 50 + EX 35), the Classic,
  ten future Classic positions in two rows on a service trench;
- central hydraulics and compressed-air plant room (~62 m2);
- water treatment building 12 x 10 m behind galvanics: buried duct
  (gravity from the +1.2 m floor), covered crossing 6 m clear;
- workshop ~200 m2 with benches, tool cabinets, 3D printers, lathe,
  small CNC mill, drill, saw, welding bay, press, washer, measuring table.

Docs: galvanics (water treatment building, proposed), crane doc (workshop
fit-out; lathe and CNC mill not yet priced; corridor now 82 m),
site-candidates Payap section rewritten, README bullet.

docs/site-candidates.md

@@ -87,8 +87,8 @@ pharmaceutical facility on the offered land is to be confirmed.
    assessment.
 5. **Plot fit.** Shape and size against the 60 × 25 m building, the
    detached utility yard and the phase 2 footprint (6 to 8 rai). The
-   Payap scenario model below fits the whole plant on a 110 m square
-   (7.6 rai) as drawn.
+   Payap scenario model below needs a 135 m square (11.4 rai) as drawn,
+   with room for ten more Classics and a reserve.
 6. **Galvanics on a campus.** Phase 5 electroplating needs the lessor's
    written consent; the zero-discharge design
    ([sustainability](sustainability.md)) becomes a lease condition, not
@@ -114,26 +114,41 @@ parametric BIM model sites it on a simple square plot:
 [isometric](cnx_vinyl_parametric_payap-iso.png)), built in FreeCAD 26.3
 from BIM walls, slabs, columns, spaces and equipment. Every size and
 position hangs off its `Params` spreadsheet (plot side, setbacks, floor
-level, building sizes, fire wall line, office gap), so the square can be
-swapped for the real plot once Payap names one. It is a layout sketch:
-every position and every equipment envelope is an estimate.
+level, building sizes, fire wall line, office and water treatment gaps),
+so the square can be swapped for the real plot once Payap names one. It
+is a layout sketch: every position and every equipment envelope is an
+estimate.
 
-- **Plot**: 110 × 110 m (12,100 m², 7.6 rai, inside the 6 to 8 rai of
-  [scale](scale.md)), road assumed on the south side, 6 m setbacks
-  (placeholder).
-- **Factory, production floor only**: 84 × 25 m at floor level +1.2 m,
-  in process order along a 54 m glazed visitor corridor. From west to
-  east: staff entry and lockers; workshop and spares, with the machine
-  door and a 12 m vehicle ramp at the north-west corner; galvanics clean
-  room and water treatment; stamper prep, PVC lab and material area;
-  compressed air and electrical; the press hall; trim and optical
-  inspection, QC lab, and finishing and packaging. Behind the fire wall
-  at 62 m are the warehouse and dispatch with two dock doors.
-  - The press hall (465 m²) holds two Duplex systems, each two HRP 12
-    presses with an EX 50 and an EX 35, and the Classic
+- **Plot**: 135 × 135 m (18,225 m², 11.4 rai), road assumed on the south
+  side, 6 m setbacks (placeholder). That is more than the 6 to 8 rai of
+  [scale](scale.md): the factory keeps room for ten more Classics, and the
+  plot keeps a reserve in front for a second hall or a PV field.
+- **Factory, production floor only**: 112 × 25 m at floor level +1.2 m,
+  16 frame bays, in process order along an 82 m glazed visitor corridor.
+  From west to east: staff entry and lockers; workshop and spares, with
+  the machine door and a 12 m vehicle ramp at the north-west corner;
+  galvanics clean room with a chemical day store; stamper prep, PVC lab,
+  material area and the electrical room; the press hall; trim and optical
+  inspection, QC lab, and finishing and packaging. Behind the fire wall at
+  90 m are the warehouse and dispatch with two dock doors.
+  - The press hall (~870 m²) holds two Duplex systems, each two HRP 12
+    presses with an EX 50 and an EX 35, the Classic, and **ten more
+    Classic positions** in two rows
     ([pressing line](equipment/pressing-line.md)).
-  - The 5 t crane runs from the west wall to the fire wall
+  - **One shared hydraulic and compressed-air supply**: a central plant
+    room (~62 m²) at the west end of the press hall, and a service trench
+    along the press rows for the hydraulic ring main, compressed air,
+    steam and cooling water.
+  - The workshop (~200 m²) is fully equipped, with 3D printers, a lathe
+    and a small CNC mill among the tools
     ([crane, workshop and tours](crane-workshop-tours.md)).
+  - The 5 t crane runs from the west wall to the fire wall.
+- **Water treatment building**, separate, 12 × 10 m at ground level
+  directly behind galvanics: zero-discharge effluent treatment, the DI
+  water plant and the chemical store. A buried duct carries the effluent
+  by gravity from the galvanics floor, and a covered crossing (6 m clear
+  for trucks) joins the galvanics door
+  ([galvanics](equipment/galvanics.md)).
 - **Office building, isolated from the factory floor**: 24 × 15 m, single
   storey, 12 m south of the factory on its own slab and structure, joined
   by a covered link that lands at the start of the visitor corridor.
@@ -142,26 +157,33 @@ every position and every equipment envelope is an estimate.
     an inner acoustic lining, the listening room, the IT and server room,
     the archive, and WC and kitchen.
   - The lathe sits away from press vibration and outside the crane zone.
-- **Utility yard** behind the press hall, across a 6 m service lane:
+- **Utility yard** behind the press hall, across a 6 m lane:
   - boiler house with chimney and a covered fuel store;
   - chiller and cooling tower;
   - process and fire water tanks;
   - PEA transformer;
-  - a pipe bridge to the press hall.
+  - a pipe bridge that drops into the service trench.
 
-  Boiler and chiller are drawn at the one-Duplex sizes and need
-  re-sizing for five presses ([scale](scale.md)).
-- **Access**: one gate on the south side opens onto a truck apron in front
-  of the dock doors, with the car park in front of the office and a
-  service road round the east end to the yard and the ramp.
-- **Area**: about 2,100 m² of factory plus 360 m² of office, so ~2,460 m²
-  under roof. That is above the 1,400 to 2,000 m² of the [scale](scale.md)
-  zone table, which held one Duplex and an automated zone with the offices
-  inside.
-  - The press hall matches the new fleet.
+  Boiler, chiller and transformer are drawn at the one-Duplex sizes. They
+  need re-sizing for five presses, and again if the Classics are added
+  ([scale](scale.md)).
+- **Access**:
+  - one gate on the south side opens onto a truck apron in front of the
+    dock doors;
+  - an access road runs along the south boundary to the car park, with
+    a footpath to the office;
+  - a lane behind the factory serves the yard, the water treatment
+    building and the ramp. The low-loader's swept path at the ramp still
+    needs checking.
+- **Area**: about 2,800 m² of factory, 360 m² of office and 120 m² of
+  water treatment, so ~3,280 m² under roof plus the boiler house. That is
+  well above the 1,400 to 2,000 m² of the [scale](scale.md) zone table,
+  which held one Duplex and an automated zone with the offices inside.
+  - Two thirds of the difference is the press hall with its expansion
+    floor.
   - Warehouse and dispatch (~530 m²) are drawn above that table's 300 to
     500 m² for packaging and finished goods.
 
-  Both are estimates to settle against the real plot.
+  All of it is an estimate to settle against the real plot.
 
 The Mueang Chi model and everything sited on it stay as they are.