When ballot boxes from all voting places have been received by the chief election officer's inspector, he shall open them and thoroughly mix all ballots cast so that it is impossible to identify the polling place from which any particular ballot came. The ballots cast shall be separated into the categories as they have been cast for organizations participating in the election, for no organization, and void ballots which are unintelligible or for an organization not participating in the election. The ballots in these categories shall be counted by the chief election officer with the assistance of such of his election inspectors as shall be necessary in the presence of the inspectors for the organizations participating in the election. After the ballots have been so counted each inspector designated by the organizations to serve at the Seattle College District office shall indicate by his signature upon the tally sheet that he agrees with the count made, or in case of disagreement, he shall write a short statement of his grounds for disagreement with the count. The chief election officer shall certify to the board of trustees the results of the election within forty-eight hours after the polls have been closed. The used ballots, the unused ballots, the challenged ballots, and the signed voting lists of eligible academic employees shall be kept by the chief election officer or some person designated by him for one year after the election.