Act as a Chartered Civil Engineer specializing in UK drainage design with expertise in Building Regulations Part H, Sewers for Adoption (SfA) 8th Edition, CIRIA SuDS Manual C753, and BS EN 752/12056 standards.

I require a comprehensive drainage design strategy for the following project:

**Project Overview:**
- Development Type: [PROJECT_TYPE] (e.g., 45-unit residential estate, 2000m² commercial unit, mixed-use scheme)
- Location: [SITE_LOCATION] (full address including postcode for rainfall data determination)
- Site Area: [SITE_AREA] (hectares/sqm)
- Proposed Layout: [DEVELOPMENT_DETAILS] (number of units, floor areas, parking provision)

**Site Characteristics:**
- Topography: [TOPOGRAPHY] (existing levels, slopes %, ridge/valley configuration)
- Ground Conditions: [SOIL_TYPE] (clay, sand, rock, infiltration rates from percolation tests if available)
- Existing Drainage Infrastructure: [EXISTING_INFRASTRUCTURE] (public sewer positions/invert levels, watercourses, proximity to WWTP)
- Constraints: [CONSTRAINTS] (trees with TPOs, contaminated land, utilities crossings, flood zones)

**Design Requirements:**
- Discharge Strategy: [DISCHARGE_METHOD] (public foul sewer + surface water sewer, combined sewer, watercourse discharge, soakaway infiltration, attenuation tank)
- Adoptability: [ADOPTION_STATUS] (adoptable under SfA/private/maintenance responsibility split)
- Climate Change Allowance: [CLIMATE_FACTOR] (typically 20-40% for UK new developments)
- Return Periods: [DESIGN_STORMS] (1-year, 30-year, 100-year critical durations)

**Mandatory Deliverables:**

1. **HYDRAULIC CALCULATIONS**
   - Foul flows: Calculate using BS EN 12056-2 (DU method) showing total flow (l/s) and pipe sizing
   - Surface water: Modified Rational Method calculations (Q=CIA) with regional 'r' values from EA/SEPA/NRW data
   - Storage requirements: If attenuation needed, show storage volume calculations (m³) for 1:100 year +CC event

2. **DRAINAGE STRATEGY LAYOUT**
   - Pipe sizing and gradients (min 1:80 for 150mm foul, per BS EN 752)
   - Manhole positioning (max 90m spacing for 150mm diameter, max 4.25m depth without pumping)
   - Invert level calculations showing falls from highest to lowest point
   - Pumping station requirements assessment if gravity drainage not viable

3. **SuDS TREATMENT TRAIN**
   - Apply SuDS hierarchy: Infiltration → Attenuation → Watercourse → Sewer (last resort)
   - Propose source control measures (permeable paving, green roofs, rainwater harvesting)
   - Treatment stages for water quality (oil separators if <5ha commercial, proprietary systems)
   - Maintenance access and ownership responsibilities

4. **COMPLIANCE & REGULATORY**
   - Building Regulations Part H compliance matrix (H1-H6)
   - Environment Agency/NRW/SEPA discharge consent requirements (if applicable)
   - Local Planning Authority SuDS Approval Body (SAB) submission requirements (England)
   - Pre-connection enquiry guidance for Utility providers (Thames Water, Yorkshire Water, etc.)

5. **RISK ASSESSMENT**
   - Flood risk mitigation (Fluvial/Pluvial/Tidal zones)
   - Groundwater protection if infiltration proposed
   - Build-over/near-sewer risks (Category 1-3 sewers)
   - Maintenance strategy (who maintains what elements)

**Calculation Standards to Reference:**
- Show all formulas used (e.g., Q = k × √DU for foul drainage)
- Reference design rainfall depths from FEH13 or EA Wallingford Procedure
- Include flow velocity checks (self-cleansing 0.7m/s min, 2.0m/s max)

**Output Format:**
Present as a formal Drainage Strategy Report suitable for Planning Application submission, with clear headings, bullet points for key decisions, and [CALCULATION REQUIRED] placeholders where site-specific survey data is essential. Include a 'Red Flags' section highlighting critical issues requiring immediate investigation before construction.