12. Inspection. All materials of whatsoever kind to be used in the work shall be subject to the inspection and approval of the Engineer and shall be subject to constant inspection before acceptance. Any imperfect work that may be discovered before its final acceptance shall be corrected immediately, and any unsatisfactory materials used in the work or delivered at the site shall be rejected and removed on the requirement of the Engineer. The inspection of any work shall not relieve the Contractor of any of his obligations to perform proper and satisfactory work as herein specified, and all work which, during the progress and before the final acceptance, may become damaged from any cause, shall be removed and replaced by good and satisfactory work without extra charge therefor. The Engineer and his assistants shall have at all times free access to every part of the work and to all points where material to be used in the work is manufactured, procured or stored and shall be allowed to examine any material furnished for use in the work under this contract. All inspection of any and all material furnished for use in work to be performed under this contract shall be made at the site of the work after the delivery of the material, provided, that, if requested by the Contractor the Engineer may at his option perform, or have performed, inspection of materials at points other than the site of the work. In any such case the Contractor shall pay the Sanitary District the extra cost of such inspection, including the necessary expenses of the inspector for the extra time expended in performing any such inspection at said other points. 13. Legal Requirements. The Contractor shall keep himself fully informed of all existing and future national and state laws and local ordinances and regulations in any manner affecting those engaged or employed in the work, or the materials used in the work, or of all such orders and degrees of bodies or tribunals having any jurisdiction or authority over the same, and shall protect and indemnify the party of the first part against any claim or liability arising from or based on the violation of such law, ordinance, regulation, order or decree, whether by himself or his employees.