SULLIVAN, C. J.
This action filed pursuant to General Laws c. 41, §81BB involves a narrow aspect of the subdivision control law and one with which the reported cases have not dealt. The plaintiff seeks a release from the defendant Halifax Planning Board (the "Board") of the principal portion of a bond in the amount of $280,000.00 deposited with the Board pursuant to the provisions of §81U of said Chapter 41. The Board has refused to release any part of the penal sum of the bond until certain work not done in accordance with the plans has been remedied. The issue resolves into a dispute concerning the adequacy of the type of retaining wall actually constructed by the plaintiff or on its behalf, the length thereof and the manner of construction. The second part of the dispute concerns the top coat of the one subdivision road called Marilyn Way (not after the author of this opinion, however). The Planning Board Rules and Regulations call for a finish course of only one inch whereas the plans showed the top coat would be one and one- half inches to which the Board seeks to hold the plaintiff. The final aspect of the controversy is the Board's right to hold the entire security although most of the work has been completed. My conclusion is that the retaining wall should not be removed and rebuilt at the present time since this seems an economic waste but that sufficient funds should be withheld by the Board to cover the eventuality of its reconstruction. In addition and as the parties have stipulated, $10,810.00 should be withheld as agreed by stipulation dated April 30, 1990 filed in the papers in this action on July 12, 1990. So far as the depth of the top coat is concerned, the plan was constructively approved, and there was no decision or conditions imposed by the Board in this regard. Accordingly the Board cannot require the plaintiff to install a top coat of greater depth than its rules and regulations specify.
A trial was held in the Land Court on Tuesday, April 3, 1990 and Friday, April 20, 1990 at which a stenographer was sworn to record and transcribe the testimony. Witnesses for the plaintiff were John Gilewicz, a structural engineer, Dennis Leary, the plaintiff's Vice President, John Keefe, registered land surveyor, and Bernard Munroe, land surveyor; and for the defendant Tyler Nims [Note 1], a registered professional engineer and consultant to the Town of Halifax on the construction of this project, and Richard Harrison, current chairman of the Planning Board. In all, twelve exhibits were admitted in evidence, some with multiple parts, which are incorporated herein for the purpose of any appeal.
On all the evidence I find and rule as follows:
1. A definitive subdivision plan entitled "Oak Hill Estates in Halifax, Mass." dated December 1, l986, revised February 18, 1987 as drawn for the plaintiff by the BSC Group was filed with the Board as File No. 8701 (Exhibit No. 1). The BSC was a successor to Malcolm T. Shaw, an engineering firm with a practice centered in Halifax and surrounding towns with whom Mr. Munroe was associated. The Board failed to act within the time constraints specified in G.L. c. 41, §81U, the plan was constructively approved and a certificate to this effect issued by the Halifax Town Clerk (Exhibit No. 2). The Board did in fact thereafter endorse the plan on February 23, 1987 and the plan was recorded as Plan No. 87-1284 on November 20, 1987 in Plan Book 29, Page 1180 of the Plymouth County Registry of Deeds to which all recording references herein refer. The plan consists of nine sheets and depicts a twelve lot subdivision and a single proposed roadway called Marilyn Way which ends in a cul-de-sac. All twelve lots have been sold. The endorsement by the Board of a constructively approved plan was a nullity. See Windsor v. Planning Board of Wayland, 26 Mass. App. Ct. 650 (1988).
2. The developer had sought a slope easement from an abutting landowner to alleviate the difference in grade between the premises owned by him and the adjoining land, but it was unsuccessful in these negotiations. Accordingly a retaining wall was required to support the 5 1\2 foot grade difference between the elevation of Marilyn Way and the adjacent bank. The plans showed that the wall was to be of a so-called "gravity" type to be constructed along the subdivision roadway beginning at the intersection of Oak Street, a public way and continuing for approximately 300 feet. The actual wall which was constructed was a "cantilevered" retaining wall with a length of 200.4 feet. There was testimony at the trial as to the differences between the two types of retaining wall, and there was no dispute among the experts that a cantilevered retaining wall was at least as desirable as a gravity type. Indeed the former has become the retaining wall of choice because it is less expensive to construct. The change made by the plaintiff by its contractor stemmed from an inability to obtain the necessary forms for a gravity retaining wall, but the change was made without approval from the Board.
3. The as-built plan was interpreted by the defendant's expert as an actual representation of the completed wall. In fact this plan, Exhibit No. 10, suggests that the engineer may have sketched a basic cantilevered retaining wall and not what was actually in the ground. The wording of the plan, "this detail provided by contractor and does not indicate a survey as-built by BSC". In fact the footing as shown on Exhibit No. 10 was to be six feet wide and one foot thick with steel reinforcements ("rebars") within the wall to be two rows with a ninety degree bend in the row facing the retained soil and the second row vertically placed within the footing. In fact the inspection by the Town's expert showed the footing to be four feet wide and six inches thick with only one row of steel reinforcements. The expert was unable to observe whether a ninety degree angle was made securing the rebar at the side of the wall the bar supported.
4. Cracks in the wall have appeared. There are several vertical cracks which do not exceed 1/16th of an inch in width which is the normal shrinkage of concrete during the drying or settling stage. There is in addition, however, a fourth crack observed by the defendant's expert in January of this year approximately 46 feet from the Oak Street end of the wall which may not have occurred if the wall had been built in accordance with Exhibit No. 10.
5. The length of the wall is approximately 100 feet less than shown on the plans. A longer wall, however, would interfere with the driveway and with Oak Street. Both experts agreed that the wall was a sufficient length, and I so find.
6. The subdivision plan shows a roadway surface of two inches of binder course, referred to in the Halifax Rules and Regulations as "finish" course and also referred to as "base" course at the trial. The binder course is not an issue. The plans also show one and one-half inches of wearing course, also referred to at the trial as "top" course and in the Rules and Regulations as "finish" course. The wearing course was actually constructed with an inch of bituminous concrete as opposed to the one and one-half inch surface shown on the plan. The Halifax Rules and Regulations call only for the latter. Apparently in the negotiations the Board agreed to waive the requirement of a thirty foot wide roadway and approve a more narrow twenty-two foot wide roadway with two twoinch berms in exchange for the added road surface. In any event waivers routinely are granted by the Board of the roadway width, and the negotiations now are without legal sanding inasmuch as the plan was constructively approved.
7. In accordance with the statutory provisions the plaintiff had posted a bond with the Town in the amount of $280,000.00. The plaintiff has made three written requests of the Board for reduction of the amount of bond held by the defendant from $280,000.00 to $71,500.00. None of the forms in which the requests were made complied with the requirements of G.L. c. 41, §81U. After the first two letters, one dated July 19, 1988 and a second letter dated August 16, 1988 (Exhibit No. 4 and 5 respectively) requesting a reduction of the bond to $71,500.00 the Board voted to issue a cease and desist order as to all construction activity, except landscaping, until such time as the plaintiff proposed to the Board satisfactory changes (Exhibit No. 6). This order was confirmed by a second vote on September 15, 1988 (Exhibit No. 7) whereby all work again was ordered halted other than that related to the removal of the wall. Subsequently by letter dated January 17, 1989 the plaintiff's counsel requested reduction of the bond to $69,161.00. A justice of this Court issued a preliminary injunction on October 4, 1988 authorizing the continuance of the work.
8. Tyler Nims, the Board's expert, prepared a letter dated January 18, 1990 (Exhibit No. 12) which estimated the cost of demolition and replacement of the wall, guardrail and sidewalk, loaming and seeding and other additional expenses as $81,000.00 which included a twenty percent increase over 1989 costs. The figure would include the cost of demolition of the wall, sidewalk and guardrail, the reconstruction of these items and the loaming and seeding of the area. It also would account for the engineering involved and preparing construction, plans and specifications to be put out to bid and proper construction inspection.
9. The parties have stipulated as follows:
a) The amount of bond "held" by the planning board is $280,000.00.
b) $10,810.00 should be withheld from the plaintiff to guarantee completion of aspects of the subdivision construction not here in issue. [Note 2]
c) The top coat was put on in compliance with the Halifax subdivision rules and regulation, but not in accord with the plan to the extent of one-half inch.
The plaintiff without observing the necessary formalities appears to have revised unilaterally the work required to bring the definitive plan to fruition. He cannot now complain if a reasonable amount is held by the Board to be certain that the revisions will not cause future road problems. Nonetheless the Board's position that no security be released is unreasonable. G.L. c. 41, §81U provides "the penal sum of any . . . bond shall bear a direct and reasonable relationship to the expected cost including the effects of inflation, necessary to complete the subject work. Such amount or amounts shall from time to time be reduced so that the amount bonded . . . continues to reflect the actual expected cost of work remaining to be completed." The Board has refused to release any of its security, however, until all of the work has been completed. This posiion cannot be supported, nor do I understand that counsel for the Board is supportive of its wish to hold the entire security.
It is clear from the record that the contractor who constructed the wall did not do so in accordance with the original definitive plan nor the as-built model. The evidence at the trial did not reveal who authorized him to make these deviations, whether it was the plaintiff or BSC's representative. In any event the changes were not approved by the Board and no waiver was issued by it. On the other hand the experts agree that a cantilevered wall is as adequate as a gravity wall, and accordingly it would be uneconomical to require that the wall be replaced with the type originally proposed. The change in the type of retaining wall, while the procedure was done incorrectly, might be lived with for Halifax is after all one of the remaining small undeveloped towns in southeastern Massachusetts, and there may well have been word of mouth communications of which counsel are not aware. This does not excuse an unauthorized deviation from the plans, but I would be slow to order the substitution of one type wall for another for this reason where the substituted wall is now generally the wall of choice. Such a result would be form prevailing over substance. However, I am concerned about the adequacy of the construction of the cantilevered retaining wall since the wall again appears to have been constructed in a manner that did not comply with the method suggested on Exhibit No. 10. It is unclear whether this is the reason for the most recent crack, but these two facts lead me to believe that the Board should retain sufficient security to do the work specified in Exhibit No. 12 if time proves that the wall was incorrectly constructed. The plaintiff's expert testified that it would be five years before faults would definitively appear, and accordingly I find and hold that sufficient sums should be withheld to replace the wall within the next five years if the Town's expert concludes during that period that replacement is required. If by January 1, 1996 he concludes that the wall as built is satisfactory, then the amounts withheld should be released. However, I find and hold that an inflation rate of twenty percent is unrealistic and would lower that factor by ten percent. The resulting figure plus the amounts agreed to by the parties as set forth in the stipulation may be withheld by the Board, the stipulated amounts until the work has been satisfactorily completed and evidence of payment of the costs thereof submitted to the Board and the remainder until January 1, 1996.
The decision of the Supreme Judicial Court in Young v. Planning Board of Chilmark, 402 Mass. 841 (1988) forestalled the Board's attempt to compel the plaintiff to add the extra one-half inch of top course since its rules and regulations did not require this. Accordingly the road need not be changed. Therefore it is only the holdback to insure that the failure by the plaintiff to contruct the retaining wall not only not in accordance with the original design but not in accordance either with the design shown on Exhibit No. 10 will be adequate for the protection of Marilyn Way that need be retained from the security. The revised figure for the wall security is $74,250.00 which together with the stipulated amount of $10,810.00 results in a total security to be retained by the Board of $85,060.00.
Judgment accordingly.
FOOTNOTES
[Note 1] Mr. Nims testified that his engineering experience is chiefly in the area of water resources, but because of his ample experience in the area of subdivision design and construction and because a retaining wall is a simple, minor structure, the Court qualified him as an expert over the continuing objection of plaintiff's counsel.
[Note 2] Per stipulation filed with the Court July 11, 1990.