(1) An impact fee deposit of $12,700.00 shall be paid by the user;

(2) The total volume of effluent in gallons shall be recorded for the initial period of six consecutive months following installation of the aforesaid sewer line;

(3) The six months' total volume shall be divided by the number of days in the six-month period to compute a daily average discharge through the sewer line;

(4) The daily average discharge in gallons shall be divided by 400 to establish the number of units to be assessed at the costs of $2,032.00 per unit (example: if the average daily discharge is 800 gallons, the sewer impact assessment shall be $4,064.00);

(5) If the sewer impact assessment for the first six months as calculated above exceeds the $12,700.00 initial deposit made, the user shall pay the difference within 15 days after written notification to user of the required adjustment. However, if the assessment as calculated above does not exceed the initial deposit, the city agrees to reimburse the difference to the user no later than 30 days after the first six-month monitoring period;

(6) For each succeeding six-month period the volume of effluent outflow shall be measured. To the extent that average daily effluent outflow in any subsequent six-month period exceeds that of the initial six-month period, an additional impact fee for the excess shall be levied as calculated and as provided for in subsections (3) and (4) of this section. Any additional fee so calculated shall be paid to the city within 15 days of written notification to user;

(7) For the initial six-month period only, if the average daily effluent outflow is less than initially projected, the city shall refund the unused portion of the impact fee as set forth above. For subsequent six-month monitoring periods, there shall be no refunds of impact fees, regardless of effluent outflow volumes.