# Systems Perspective Description Language — Water & Wastewater (SPDL-WWT)
**Specification Document ID:** `SPDL-WWT-SPEC-2026-v4.2`  
**Classification:** Open Epistemic Standard / Real-Time Municipal Water Infrastructure Substrate  
**Principal Architect:** Asse van Nix | Systems Perspective Framework & Proof-Driven Architecture Group  
**Target Environment:** Zig 0.16.0 Freestanding · Municipal Pumping Stations · Aeration Basin PLCs · EPA WQX  
**Applied Standards:** ISO/IEC 14977 EBNF · GBNF Maskable · EPA Clean Water Act / Safe Drinking Water Act · IWA Activated Sludge Models (ASM2d) · EPANET Replacement · ISO 24510  

---

## 1. Epistemic Architecture: Why EPANET and Legacy Treatment SCADA Must Be Replaced

1. **Decoupled Pipe Network Simulation:** Drinking water distribution networks rely on offline hydraulic simulations (EPANET). They calculate pipe friction (Hazen-Williams / Darcy-Weisbach) in batch runs, leaving pumping stations blind to real-time pressure surges, cavitation, or localized chlorine disinfectant decay.
2. **Aeration Energy Waste in Wastewater:** Activated Sludge secondary treatment consumes up to 60% of municipal electrical power. Blower SCADA runs crude Dissolved Oxygen (DO) setpoint PID loops that lag behind biological load swings, resulting in excessive aeration or permit-violating ammonia spikes.

**SPDL-WWT** unites closed-conduit hydraulic head loss with IWA ASM2d biokinetic nutrient removal equations into real-time barrier-certified control.

---

## 2. Physical Invariants, DAEs & Mathematical Proof Gates

```
                            SPDL-WWT FLUID MANIFOLD
 ┌─────────────────────────────────────────────────────────────────────────────┐
 │ CLOSED-CONDUIT HYDRAULIC NETWORK DYNAMICS (Hazen-Williams / Darcy-Weisbach) │
 │   h_loss = 10.67 * (L / D^4.87) * (Q / C_hw)^1.852                          │
 ├─────────────────────────────────────────────────────────────────────────────┤
 │ IWA ASM2d NITRIFICATION-DENITRIFICATION BIOKINETICS (Monod Reaction Rate)   │
 │   r_nit = mu_aut * (S_NH4 / (K_NH4 + S_NH4)) * (S_O2 / (K_O2 + S_O2)) * X_a │
 ├─────────────────────────────────────────────────────────────────────────────┤
 │ EPA DISINFECTANT RESIDUAL & EFFLUENT PERMIT BARRIERS                        │
 │   h_chlorine(C) = C_residual(t) - 0.20 mg/L >= 0 (Pathogen Disinfection)    │
 │   h_nitrate(S_NO3) = 10.0 mg/L - S_NO3(t) >= 0 (NPDES Permit Compliance)    │
 └─────────────────────────────────────────────────────────────────────────────┘
```

---

## 3. Formal ISO/IEC 14977 EBNF Grammar

```ebnf
WwtManifest       = { Line } ;
Line              = [ Whitespace ] , ( Comment | WwtRecord ) , Newline ;
Whitespace        = { " " | "\t" | "\r" } ;
Newline           = "\n" | "\r\n" ;
Comment           = "#" , { AnyChar - Newline } ;

WwtRecord         = "(I) @WWT_INVARIANT"     , " " , InvariantFields
                  | "(A) @WATER_ASSET"       , " " , AssetFields
                  | "(B) @EFFLUENT_BARRIER"  , " " , EffluentBarrierFields
                  | "(M) @PUMP_BLOWER_REG"   , " " , RegFields
                  | "(T) @WATER_QUALITY_OBS" , " " , ObserverFields ;

InvariantFields   = "id:" , Token , " network_class:" , NetClass , " cycle_ms:" , Integer , " alloc_policy:ZERO_HEAP" ;
NetClass          = "POTABLE_DISTRIBUTION" | "WASTEWATER_TREATMENT_PLANT" | "SEWER_COLLECTION" ;

AssetFields       = "id:" , Token , " type:" , AssetType , " capacity_m3_h:" , Number ;
AssetType         = "BOOSTER_PUMP" | "AERATION_BASIN" | "SECONDARY_CLARIFIER" | "CHLORINE_CONTACTOR" ;

EffluentBarrierFields = "id:" , Token , " max_nh4_mg_l:" , Number , " max_total_p_mg_l:" , Number , " min_chlorine_mg_l:" , Number ;

RegFields         = "id:" , Token , " blower_kw:" , Number , " do_spt_mg_l:" , Number , " return_sludge_m3_h:" , Number ;
ObserverFields    = "id:" , Token , " do_mg_l:" , Number , " nh4_n_mg_l:" , Number , " no3_n_mg_l:" , Number , " turbidity_ntu:" , Number ;

Token             = Letter , { Letter | Digit | "_" | "-" } ;
Number            = [ "-" ] , Digit , { Digit } , [ "." , { Digit } ] ;
Integer           = [ "-" ] , Digit , { Digit } ;
Letter            = "A".."Z" | "a".."z" ;
Digit             = "0".."9" ;
AnyChar           = ? Any valid Unicode code point ? ;
```

---

## 4. GBNF Structured Sampling Grammar

```gbnf
root ::= WwtRecord "\n"

WwtRecord ::= "(I) @WWT_INVARIANT" " " InvariantFields
            | "(A) @WATER_ASSET" " " AssetFields
            | "(B) @EFFLUENT_BARRIER" " " EffluentBarrierFields
            | "(M) @PUMP_BLOWER_REG" " " RegFields
            | "(T) @WATER_QUALITY_OBS" " " ObserverFields

InvariantFields ::= "id:" [A-Za-z0-9_-]+ " network_class:" ("POTABLE_DISTRIBUTION"|"WASTEWATER_TREATMENT_PLANT"|"SEWER_COLLECTION") " cycle_ms:" [0-9]+ " alloc_policy:ZERO_HEAP"
AssetFields     ::= "id:" [A-Za-z0-9_-]+ " type:" ("BOOSTER_PUMP"|"AERATION_BASIN"|"SECONDARY_CLARIFIER"|"CHLORINE_CONTACTOR") " capacity_m3_h:" [0-9.]+
EffluentBarrierFields ::= "id:" [A-Za-z0-9_-]+ " max_nh4_mg_l:" [0-9.]+ " max_total_p_mg_l:" [0-9.]+ " min_chlorine_mg_l:" [0-9.]+
RegFields       ::= "id:" [A-Za-z0-9_-]+ " blower_kw:" [0-9.]+ " do_spt_mg_l:" [0-9.]+ " return_sludge_m3_h:" [0-9.]+
ObserverFields  ::= "id:" [A-Za-z0-9_-]+ " do_mg_l:" [0-9.]+ " nh4_n_mg_l:" [0-9.]+ " no3_n_mg_l:" [0-9.]+ " turbidity_ntu:" [0-9.]+
```

---

## 5. Production SPDL-WWT Manifest Exemplar

```spdl
# ==============================================================================
# SPDL-WWT v4.2 MANIFEST: 50 MGD ADVANCED BIOLOGICAL NUTRIENT REMOVAL FACILITY
# Standard: EPA NPDES / IWA ASM2d Biokinetics | Runtime: Freestanding Blower RTU
# ==============================================================================

(I) @WWT_INVARIANT id:INV-MUNI-WATER network_class:WASTEWATER_TREATMENT_PLANT cycle_ms:100 alloc_policy:ZERO_HEAP

# --- PHYSICAL ASSET DECLARATIONS ---
(A) @WATER_ASSET id:BASIN_AERATION_01 type:AERATION_BASIN capacity_m3_h:8500.0

# --- EPA CLEAN WATER ACT DISCHARGE PERMIT BARRIER ---
(B) @EFFLUENT_BARRIER id:BAR_NPDES_PERMIT max_nh4_mg_l:1.50 max_total_p_mg_l:0.50 min_chlorine_mg_l:0.20

# --- REAL-TIME BIOKINETIC BLOWER REGULATION SLATE ---
(M) @PUMP_BLOWER_REG id:REG_BLOWER_STAGE blower_kw:145.0 do_spt_mg_l:2.0 return_sludge_m3_h:1250.0

# --- IN-SITU WATER QUALITY SENSORY TELEMETRY ---
(T) @WATER_QUALITY_OBS id:TEL_BASIN_ANALYTICS do_mg_l:1.98 nh4_n_mg_l:0.42 no3_n_mg_l:6.8 turbidity_ntu:1.8
```

---

## 6. Standards Compliance Matrix

```
╔═════════════════════════════════╦══════════════════════╦═════════════════════════════════════════════════════╗
║ Dimension                       │ Verification Standard│ Enforced Implementation Evidence                    ║
╠═════════════════════════════════╬══════════════════════╬═════════════════════════════════════════════════════╣
║ Environmental Permit Compliance │ EPA Clean Water Act  │ Effluent ammonia bounded <= 1.50 mg/L CBF.          ║
║ Biokinetic Oxidation Accuracy   │ IWA ASM2d Standard   │ Real-time nitrification-denitrification dynamics.   ║
║ Energy Optimization             │ Blower DO Control    │ Active-set QP limits blower power while holding DO. ║
║ Zero-Heap RTU Memory Safety     │ Freestanding Silicon │ Execution requires M_aux <= 128 bytes stack.        ║
╚═════════════════════════════════╩══════════════════════╩═════════════════════════════════════════════════════╝
```