The planning agency of Hempfield Township shall prepare the text and map of the proposed Zoning Ordinance as well as make all necessary studies and surveys preliminary thereto, whenever instructed to do so by the governing body. In preparing a proposed Zoning Ordinance, the planning agency shall hold at least one public hearing pursuant to public notice and may hold additional public hearings upon such notice as it shall determine to be advisable. Upon the completion of its work, the planning agency shall present to the governing body the proposed Zoning Ordinance, together with recommendations and explanatory materials. The procedure set forth in this section shall be a condition precedent to the validity of a Zoning Ordinance adopted pursuant to this chapter. If a county planning agency shall have been created for Westmoreland County, then at least 30 days prior to the submission of the ordinance to the local governing body, the Hempfield Township planning agency shall submit the proposed ordinance to said county planning agency for recommendations.