test/app/Http/Models/SiteStation.php

<?php

namespace App\Http\Models;

use Illuminate\Database\Eloquent\Model;

class SiteStation extends Model
{
    protected $table = 'sites_station';
    protected $primaryKey = 'site_id';
    public $incrementing = false;
    protected $guarded = [];

    protected $casts = [
        'other_sites' => 'array',
        'portal_sites' => 'array',
        'compete_sites' => 'array'
    ];
}