The local authority of each city, borough, town district, or road district, the whole or part of which is comprised within the drainage district, shall within thirty days of receiving the written notice mentioned in section forty-eight hereof pay to the secretary of the Drainage Board one-half of the amount of such assessment, and shall pay the other half thereof within six calendar months of the date of the receipt of such notice as aforesaid. In case either half is not so paid such local authority shall be liable to and shall pay interest on any and every amount so remaining unpaid until payment thereof at the rate for the time being charged by the bankers of the Drainage Board for moneys owing to them by the said Board or that would be chargeable if such moneys were owing, as the case may be:

“Provided that if an appeal against any assessment has been lodged under section fifty hereof, then the amount fixed by the Court shall be substituted for the amount of such assessment, and payment of one-half thereof shall be made within thirty days from the date of the Court’s decision, but interest on such half shall be payable at the rate aforesaid as from the expiration of thirty days from the receipt of the original assessment.”