{
  "answerability": "evidence_backed_claims_available",
  "claims": [
    {
      "claim": {
        "claim_id": "claim-park-black-diamond-mines-regional-preserve-boundary-geometry-20260924",
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        "spatial_scope_ids": [],
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          "boundary_geometry_snapshot": {
            "feature_ids": [
              "ebrpd:15",
              "ebrpd:539"
            ],
            "path": "geometry/v0/snapshots/ebrpd-managed-land-boundaries-20260924.geojson",
            "sha256": "4e6558956f4f397816d719ff87554289e08dd495314b2d57c83d1634f083e3e5"
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          "boundary_type": "managed_land_status_polygons",
          "coordinate_precision_decimal_degrees": 5,
          "coordinate_reference_system": "EPSG:4326",
          "navigation_grade": false
        }
      },
      "evidence": [
        {
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          "evidence_id": "evidence-park-black-diamond-mines-regional-preserve-boundary-geometry-20260924",
          "notes": "Supports the selected source polygons and their retained boundary semantics.",
          "observation_id": "observation-managed-land-boundaries-ebrpd-20260924",
          "stance": "supports"
        }
      ],
      "observations": [
        {
          "artifact_refs": [
            "geometry/v0/snapshots/ebrpd-managed-land-boundaries-20260924.geojson"
          ],
          "content": "EBRPD's open-data layer reports the selected current managed-land polygons; parkland and landbank status remain separate.",
          "observation_id": "observation-managed-land-boundaries-ebrpd-20260924",
          "observed_at": null,
          "observer": "",
          "retrieved_at": "2026-09-24T22:00:00+00:00",
          "source_id": "source-ebrpd-managed-land-boundaries-20260924"
        }
      ],
      "sources": [
        {
          "locator": "https://services2.arcgis.com/jeEP9c9zZoQQwtck/arcgis/rest/services/EBRPD_Parks/FeatureServer/0",
          "publisher": "East Bay Regional Park District",
          "source_id": "source-ebrpd-managed-land-boundaries-20260924"
        }
      ],
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        "entity_id": "park-black-diamond-mines-regional-preserve",
        "kind": "park",
        "name": "Black Diamond Mines Regional Preserve"
      }
    },
    {
      "claim": {
        "claim_id": "claim-black-diamond-camps-reserveamerica",
        "evidence_ids": [
          "evidence-black-diamond-camps-reserveamerica"
        ],
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        ],
        "subject_id": "facility-reserveamerica-black-diamond-110452",
        "temporal_scope": null,
        "value": {
          "facility_id": "110452",
          "products": [
            {
              "maximum_people": 35,
              "product_id": "1101",
              "site_id": "group-camp-black-diamond-star-mine"
            },
            {
              "maximum_people": 20,
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              "site_id": "backpack-camp-black-diamond-stewartville"
            }
          ]
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      },
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        {
          "claim_id": "claim-black-diamond-camps-reserveamerica",
          "evidence_id": "evidence-black-diamond-camps-reserveamerica",
          "notes": "Live booking inventory product mappings.",
          "observation_id": "observation-reserveamerica-black-diamond-20260922",
          "stance": "supports"
        }
      ],
      "observations": [
        {
          "artifact_refs": [
            "Facility EB/110452",
            "Products 1101-1102"
          ],
          "content": "ReserveAmerica lists Star Mine as product 1101 (35) and Stewartville as product 1102 (20), with Stewartville closed November 1 through March 31.",
          "observation_id": "observation-reserveamerica-black-diamond-20260922",
          "observed_at": null,
          "observer": "Wayproof browser source review",
          "retrieved_at": "2026-09-22T00:00:00-07:00",
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        {
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          "publisher": "ReserveAmerica / East Bay Regional Park District",
          "source_id": "source-reserveamerica-black-diamond-campsites"
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      ],
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        "entity_id": "facility-reserveamerica-black-diamond-110452",
        "kind": "booking_facility",
        "name": "Black Diamond Mines ReserveAmerica Facility"
      }
    },
    {
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        "claim_id": "claim-black-diamond-camps-official",
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        ],
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        ],
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        "value": {
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            "maximum_nights": 2,
            "maximum_people": 35,
            "minimum_advance_business_days": 3,
            "picnic_tables": true,
            "pit_toilet": true,
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          },
          "stewartville": {
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            "picnic_tables": true,
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          }
        }
      },
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        {
          "claim_id": "claim-black-diamond-camps-official",
          "evidence_id": "evidence-black-diamond-camps-official",
          "notes": "Official park camping details.",
          "observation_id": "observation-ebrpd-black-diamond-camping-20260922",
          "stance": "supports"
        }
      ],
      "observations": [
        {
          "artifact_refs": [
            "Camping"
          ],
          "content": "Star Mine is an organized educational group camp for up to 35, two-night maximum, eight cars, picnic tables, pit toilet, no water, and three-business-day booking. Stewartville holds 20, is 3.2 miles from headquarters, has picnic tables, pit toilet and non-potable horse water, a two-night maximum, and two-business-day booking.",
          "observation_id": "observation-ebrpd-black-diamond-camping-20260922",
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          "retrieved_at": "2026-09-22T00:00:00-07:00",
          "source_id": "source-ebrpd-black-diamond-park-page"
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      ],
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        {
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          "source_id": "source-ebrpd-black-diamond-park-page"
        }
      ],
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        "entity_id": "park-black-diamond-mines-regional-preserve",
        "kind": "park",
        "name": "Black Diamond Mines Regional Preserve"
      }
    },
    {
      "claim": {
        "claim_id": "claim-black-diamond-visitor-profile",
        "evidence_ids": [
          "evidence-ebrpd-black-diamond-visitor-profile"
        ],
        "predicate": "visitor_profile",
        "spatial_scope_ids": [
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        ],
        "subject_id": "park-black-diamond-mines-regional-preserve",
        "temporal_scope": null,
        "value": {
          "acreage": 8533,
          "address": "5175 Somersville Road, Antioch, CA 94509",
          "camping": {
            "Star Mine Group Camp": {
              "capacity": 35,
              "minimum_advance_business_days": 3,
              "pit_toilet": true,
              "water": false
            },
            "Stewartville Backpack Camp": {
              "capacity": 20,
              "distance_from_headquarters_miles": 3.2,
              "minimum_advance_business_days": 2,
              "pit_toilet": true,
              "water": "non-potable horse water; treat for human use"
            }
          },
          "mine_access": "Beyond the visitor center only through the Coal Mine Experience; minimum age 7",
          "parking_fee_condition": "when kiosk is attended; seasonal weekends and some holidays",
          "parking_fee_usd": 5,
          "seasonal_gate_hours": "08:00 opening; closing varies from 17:00 to 20:00 by published date bands"
        }
      },
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        {
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          "notes": "Direct transcription and conservative structuring of planning-relevant fields from the official park page.",
          "observation_id": "observation-ebrpd-black-diamond-visitor-profile",
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        }
      ],
      "observations": [
        {
          "artifact_refs": [
            "Overview",
            "To Reach The Park",
            "Attractions"
          ],
          "content": "The live park page publishes the visitor profile represented by the associated claim, including access, operating information, facilities, and material restrictions.",
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          "observed_at": null,
          "observer": "Wayproof live source review",
          "retrieved_at": "2026-09-20T07:00:00+00:00",
          "source_id": "source-ebrpd-black-diamond-park-page"
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      ],
      "sources": [
        {
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          "source_id": "source-ebrpd-black-diamond-park-page"
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      ],
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        "name": "Black Diamond Mines Regional Preserve"
      }
    }
  ],
  "entity": {
    "entity_id": "park-black-diamond-mines-regional-preserve",
    "kind": "park",
    "name": "Black Diamond Mines Regional Preserve"
  },
  "gap_details": [],
  "history": [
    {
      "action": "ADD",
      "change_set_id": "wp-20260920-ebrpd-preserves-batch-01",
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      "knowledge_gap_refs": [],
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      "record_type": "entity",
      "summary": "Add four previously uncaptured EBRPD preserve visitor profiles."
    },
    {
      "action": "ADD",
      "change_set_id": "change-managed-land-boundary-backfill-20260924",
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    {
      "action": "ADD",
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    {
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      "evidence_refs": [],
      "knowledge_gap_refs": [],
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    {
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  ],
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  "knowledge_gaps": [],
  "reference_evidence": [],
  "relationships": [
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      "evidence_ids": [
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      "object_id": "park-black-diamond-mines-regional-preserve",
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    },
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      "relationship_id": "relationship-contra-loma-connects-black-diamond",
      "subject_id": "park-contra-loma-regional-park",
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  ],
  "route_geometry": null,
  "route_geometry_url": null,
  "type": "canonical_entity"
}