1. One hundred percent of the total estimated cost of the improvement or act to be performed conditioned upon the faithful performance of the act or agreement;

2. Fifty percent of the total estimated cost of the improvement or act to be performed securing payment to the contractor, the subcontractors and to persons furnishing labor, materials or equipment to them for the improvement or the performance of the required act; provided, however, where the security provided is that referenced in Section 16.32.020, no additional sum shall be required to guarantee payment provided the security instrument authorizes draws to pay for labor and materials and specifies that not more than fifty percent of the total shall be released, except to the city to pay for completion of improvements, until after the sixty-day lien period has expired;

3. Ten percent of the total estimated costs of the improvements, to be provided prior to city acceptance of completion, to guarantee or warranty the work for a minimum period of one year following completion and acceptance thereof against any defective work or labor done, or defective materials furnished;

4. If the improvement security is a bond or bonds furnished by duly authorized corporate surety, an additional security in the amount of fifteen thousand dollars or fifteen percent of the total estimated cost of improvements, whichever is less, shall be included to cover the cost and reasonable expenses and fees which may be incurred by the city in successfully enforcing the obligation secured. The improvement security shall also secure the faithful performance of any changes or alterations which do not exceed ten percent of the original estimated cost of the improvement.