var boudingGraphic = new Graphic();
boudingGraphic.geometry = boundingGeom;

var boudingFeature = new FeatureSet();
boudingFeature.features = [boudingGraphic];

var queryFeatures = new FeatureSet();
queryFeatures.features = features;

var bufferDist = selectSite.bufferDistance[layerIndex];

var gpUrl = selectSite.dataConfig.GeoprocessingService.SelectSite_Buffer;
var gp = new Geoprocessor(gpUrl);

var linearUnit = new LinearUnit({
       "distance": bufferDist,
       "units": "meters"
});

var gpParams = {
       "BoudingFeature": boudingFeature,
       "QueryFeatures": queryFeatures,
       "BufferDistance": linearUnit
}

var selectSitePromiseArr = [];
selectSitePromiseArr.push(gp.execute(gpParams));
All(selectSitePromiseArr).then(function (diffResults) {
      console.log(diffResults);
})