Ember: how to add params from router to adapter

I'm trying to fetch data from the following URL structure:

${ENV.APP.API_HOST}/api/v1/customers/:customer_orgCode/sites/

I'm using an adapter to shape the request with buildURL with the following files:

// router.js
this.route('sites', { path: 'customers/:customer_orgCode/sites' }, function() {
    this.route('show', { path: ':site_id' });
});

// adapters/site.js
export default ApplicationAdapter.extend({
  buildURL (modelName, id, snapshot, requestType, query) {
    // return `${ENV.APP.API_HOST}/api/v1/customers/${snapshot???}/sites/`;
    return `${ENV.APP.API_HOST}/api/v1/customers/239/sites/`;
  }
}

// routes/sites/index.js
export default Ember.Route.extend({
  model: function() {
    let superQuery = this._super(...arguments),
        org = superQuery.customer_orgCode;
    this.store.findAll('site', org);
  }
});

I'm able to get the customer_orgCode on the model, but unable to pull it into the adapter. I've noted that the model isn't being populated in the Ember inspector, but the sites data is present when I make the request. Does anyone know how I can dynamically populate the buildURL with the customer_orgCode from the params on the router? And then specify sites/index to use the 'site' model?