LAY, Chief Judge.

Willard Vosburg brought this 42 U.S.C. § 1983 (1982) action, seeking monetary and injunctive relief. Vosburg claims that Herman Solem, Warden of the South Dakota State Penitentiary, and Richard D. Rist, Associate Warden, violated his right to be free from cruel and unusual punishment. Following a five-day trial, the jury returned a verdict awarding Vosburg $10,000 on his section 1983 claim. We affirm the judgment on the verdict, award attorney's fees and post-verdict interest, and we remand the case to the district court with directions to dismiss the prayer for injunctive relief as moot.

Background

Vosburg entered the South Dakota State Penitentiary on December 16, 1982, to begin serving his sentence for possession of a stolen motor vehicle. It was his first time in prison. At the time, Vosburg was nineteen years old. He weighed approximately 135 pounds.

Two days after Vosburg entered the penitentiary, Edward Abbenhaus was brought to the penitentiary to serve out his sentence. Abbenhaus had killed his mother by strangling her. Vosburg and Abbenhaus met in the "intake area" of the penitentiary. Abbenhaus soon asked Vosburg to share a cell ("double cell") with him. At that time, the penitentiary did not have a policy of segregating inmates in the intake area based upon the nature of their crime, criminal record, or psychological profile. With the prison officials' approval, Vosburg was placed in a cell with Abbenhaus.

Four days after Vosburg and Abbenhaus began double celling, Abbenhaus assaulted Vosburg. Abbenhaus shoved a piece of cloth into Vosburg's mouth and raped him. Word of Vosburg's rape spread throughout the prison. Vosburg was sexually assaulted again on three separate occasions by three other inmates.

After his release in February of 1984, Vosburg brought this section 1983 action. Following the return of the jury's verdict, the district court took Vosburg's requests for injunctive relief under advisement. After several months' consideration, the district court granted Vosburg partial injunctive relief, requiring defendants to report to county and state law enforcement officials all cases in which the prison authorities had reasonable cause to believe that a rape had occurred in the penitentiary. The district court, however, denied Vosburg's request for an injunction prohibiting double celling inmates in the intake and protective custody areas of the penitentiary. The district court also denied defendants' motions for judgment notwithstanding the verdict and a new trial, and awarded Vosburg attorney's fees and costs under 42 U.S.C. § 1988.

Liability

The prison officials urge this court to reverse the district court's denial of their motion for a judgment n.o.v. on the ground that Vosburg failed to prove that they acted with reckless disregard of his right to protection from attacks of other inmates. The district court submitted the issue of liability to the jury under the following instruction:

Prison officials may be liable for a violation of a prisoner's civil rights where they are deliberately indifferent to a prisoner's constitutional right to be free from sexual attacks by other inmates, if they actually intend to deprive him of that right, or if they act with reckless disregard of this right.

Reckless disregard of a prisoner's right to be free from sexual attacks by other inmates may be shown by the existence of a pervasive risk of harm to inmates from other prisoners and a failure by prison officials to reasonably respond to that risk.

A pervasive risk of harm may not ordinarily be shown by pointing to a single incident or to isolated incidents, but it may be established by much less than proof of a reign of violence and terror in the particular institution. It is enough that violence and sexual assaults occur with sufficient frequency that prisoners are put in reasonable fear for their safety and to reasonably apprise prison officials of the existence of the problem and the need for protective measures.

It is not necessary to show that all prisoners suffer a pervasive risk of harm. It is enough that an identifiable group of prisoners do, if the complainant is a member of that group.

There is no challenge to this instruction. It clearly reflects the applicable law. See Martin v. White, 742 F.2d 469, 474 (8th Cir. 1984); Wade v. Haynes, 663 F.2d 778 (8th Cir. 1981), aff'd, 461 U.S. 30, 103 S.Ct. 1625, 75 L.Ed.2d 632 (1983). Solem and Risk argue that Vosburg failed to prove that the risk of violence and sexual assault was substantial enough to put them on notice of the danger Vosburg faced. The defendants also maintain that prison policies, such as orientation for new inmates, availability of protective custody, and training of prison personnel, were adequate to address the existing level of violence at the penitentiary. We are satisfied, however, that sufficient evidence supports the jury's finding of liability.

The evidence contains specific and detailed accounts of the four separate instances in which Vosburg was sexually assaulted. Other young inmates also gave evidence that they had been raped repeatedly at the penitentiary, both in the intake area and other locations throughout the facility. Both sides presented statistical evidence as to the level of violence and sexual assault in the penitentiary. Vosburg also presented evidence that revealed that prison officials failed to refer assaults to the local prosecutors. The prison official in charge of investigating crimes at the South Dakota State Penitentiary testified that of approximately 500 crimes investigated by him between 1984 and 1985, only two or three were referred to prosecution. Conversely, the defendant's own expert witness, Warden Winston Satran of the North Dakota State Penitentiary, testified that all crimes committed in the North Dakota institution are referred to the local prosecutor. Furthermore, disciplinary reports revealed that there were over 140 instances of fighting and assaults from 1981 to 1985 in the South Dakota institution. None were referred to the local prosecutor. No sexual assaults at the South Dakota Penitentiary, including an instance in which an inmate had a broomstick shoved into his rectum, have ever been prosecuted. No inmate who has ever been accused of committing a rape in the South Dakota State Penitentiary, including Vosburg's assailants, has ever been disciplined.

Vosburg also presented extensive testimony as to the prison authorities' failure to respond to the risk of sexual assault; testimony that revealed that the prison authorities did not screen violent offenders from the less violent and non-violent when making cell assignments. Inmates were not segregated based upon the nature of the crime for which they were convicted, and no policy existed to segregate inmates who were the likely targets of sexual assaults. Warden Satran testified that at the North Dakota State Penitentiary newly-admitted inmates are screened and those convicted of violent crimes are segregated from the other inmates until prison authorities have an opportunity to assess their behavior. Warden Satran stated that if he had known what Warden Solem knew concerning the crimes with which Vosburg and Abbenhaus had been convicted, those two inmates would not have been double celled in his institution.

Both sides presented expert opinion testimony about the adequacy of the prison policies in place to protect the inmates from violence and sexual assault. Evidence adduced at trial revealed that prison authorities permitted the use of a pass system that allowed prisoners to have young inmates, like Vosburg, brought to an isolated area within the prison where no guards were stationed. Vosburg also presented evidence which illustrated that guards were stationed in a location removed from the inmates, where they could not see into the individual inmates' cells. Evidence revealed that one guard attempted to monitor 175 cells on four separate tiers during the night. Many of these cells housed two prisoners and monitoring rounds were conducted only every three or four hours.

The frequency of assaults at the penitentiary was sufficiently high that a jury might reasonably find pervasive risk of harm to the prisoners. The prison officials' failure to develop administrative policies to protect Vosburg and others in the intake facility and other high-risk areas of the penitentiary clearly supports a jury finding that the defendants failed to reasonably respond to the risk of inmate assault. Accordingly, we affirm the district court's denial of the defendants' motion for a judgment n.o.v. and a new trial.

Instructions

The prison officials urge in the alternative that the district court erred in denying their motion for a new trial on the ground that there was an erroneous jury instruction on damages. Although the defendants did not object to the instructions as required under Fed.R.Civ.P. 51, they maintain that we should consider the damage instructions as plain error and hold that the failure to object should not bar them from raising the issue on appeal. Defendants argue that the instruction challenged has now been held to be erroneous by the Supreme Court of the United States and that such holding occurred after the trial in the present case. Assuming, without deciding, that this would present an exception under Rule 51 to recognize plain error, we find that the error committed was harmless and not prejudicial under the circumstances of this case.

In Memphis Community School Dist. v. Stachura, 477 U.S. 299, 106 S.Ct. 2537, 91 L.Ed.2d 249 (1986), the Supreme Court held that a jury instruction authorizing an award of compensatory damages based upon the fact-finding assessment of the value or importance of a substantive constitutional right constituted an erroneous charge. We find little variance between the instruction given here and the charge rendered in Stachura. We therefore hold that the instruction given by the trial court was in fact erroneous. See id. at 312-13, 106 S.Ct. at 2546.

We note in the present case that the trial court instructed the jury that if there was a constitutional violation then the jury should award damages based upon: "(1) The physical harm suffered, including physical pain and discomfort; (2) The emotional and mental harm suffered, including fear, humiliation and mental anguish; (3) The extent and duration of his injuries;" as well as "discretionary" damages for violation of Vosburg's constitutional right to be free from cruel and unusual punishment. In Stachura, the Court found that the damages awarded were "probably significant" as they related to the value given for the violation of the constitutional right. The Stachura Court indicated that the award was not derived from any monetary loss and that a major point of the damages was to "compensate" plaintiff for the abstract value of his due process and first amendment right. Id.

We are confronted with a much different record. In the present case the record demonstrates that plaintiff was sexually assaulted on four different occasions. On each of these occasions the record illustrates both the substantial emotional and physical harm the plaintiff suffered. Vosburg was a youth of nineteen years. At trial, an expert testified that rape is the most devastating nonlethal offense that a person can endure. Young Vosburg most certainly will live with, and may suffer from these acts of human degradation for the rest of his life. The details of some of these assaults provide the specifics of Vosburg's vicious and sickening experience.

Our research also reveals that in sexual assault cases, damage awards throughout the country can easily reach the six-figure level. In the present case the award was at a minimal level almost approaching inadequacy. There is no cross appeal here on the inadequacy of the award and we therefore do not address that issue. However, it is clear that the paltry sum awarded the plaintiff is barely reasonable for the damages he incurred. Any award by the jury for the mere abstract violation of the eighth amendment was indeed minimal. We are confident that another jury, on retrial of the case on damages only, could easily return an award substantially greater than that which was returned. On this basis, although there was error, we find the error harmless.

Injunctive Relief

Vosburg sought injunctive relief as it pertained to double celling. Based upon the testimony in the case both from the plaintiff and other youthful inmates illustrating the considerable frequency of assaults, the district court granted Vosburg's request for injunctive relief in part ordering the defendants to report to the Attorney General and to the State's Attorney for Minnehaha County all cases in which they had reasonable cause to believe that a rape had occurred at the prison. The district court, however, denied injunctive relief against double celling because subsequent to the jury trial the South Dakota penitentiary adopted written rules (1) prohibiting double celling of inmates in the orientation and indoctrination unit except when it was considered necessary for suicide prevention, and (2) prohibiting inmates convicted of crimes against other persons being double celled with inmates convicted of nonviolent crimes. The court also noted that the issue of double celling in the protective area of the prison had earlier been addressed by Chief Judge Porter in Cody v. Hillard, 599 F. Supp. 1025 (D.S.D. 1984).

In Cody, Judge Porter enjoined double celling in the protective custody area. On this basis Judge Jones asserted injunctive relief beyond that rendered in Cody would not be necessary. On October 6, 1987, the panel opinion in Cody v. Hillard, 799 F.2d 447 (8th Cir. 1986), which affirmed the district court, was reversed by this court en banc. Cody v. Hillard, 830 F.2d 912 (8th Cir. 1987) (en banc), cert. denied, ___ U.S. ___, 108 S.Ct. 1078, 99 L.Ed.2d 237 (1988). The effect of the en banc decision was to reverse the district court's award of injunctive relief with respect to double celling. The en banc court noted that although there was evidence of fighting and assaults between inmates, 599 F. Supp. at 1033, nothing in the record showed the comparative number of incidents of violence before and after double celling. This court held because the district court did not make a finding of fact on this issue, there was no evidentiary basis for a finding that the elimination of double celling would alleviate the problems within the prison. Cody, 830 F.2d at 914.

In the present case, the record is replete with evidence of sexual assaults both on the plaintiff and upon other younger inmates. In the summer of 1981, an eighteen- or nineteen-year-old boy was raped three times by his cell mate. He tried to commit suicide after the rapes. The record in this case also reveals that more than 500 crimes were investigated in the South Dakota prison between 1984 and 1985 and that there were over 140 instances of fighting and assaults during that period of time. It is now 1988. Although South Dakota has made substantial changes in the prison system, as evidenced by a later report filed in the Cody case by the prison authorities, we have no way of knowing whether these additional changes have effectively provided a means to prevent the serious assaults revealed by the record before us. However, this issue cannot be decided here. Although the state has not made a suggestion of mootness, the briefs suggest that Vosburg was released in October of 1986. We assume this to be true although the record is otherwise silent as to this fact. On this basis the issue of injunctive relief appears to be moot. See Murphy v. Hunt, 455 U.S. 478, 102 S.Ct. 1181, 71 L.Ed.2d 353 (1982). The case would not fall within the narrow exception as providing challenged action of short duration and capable of repetition because there would be no reasonable expectation that Vosburg would be subjected to the same action again. Id. We therefore dismiss the appeal on the denial of the injunctive relief as moot.

Attorney's Fees

The trial court awarded attorney's fees in this case under 42 U.S.C. § 1988. The trial court is in a much better position than this court to view the evidence and to evaluate the testimony and the work product of the attorney. We feel the award made by the trial court is a reasonable one and should be sustained. In doing so we offer our commendation to Michael J. Schaffer, plaintiff's attorney, for the obvious public service that has been performed in the detailed production of evidence that fills nine volumes of trial testimony.

Post-Judgment Interest

The trial court failed to award postjudgment interest on the plaintiff's verdict. Title 28 U.S.C. § 1961 provides that "interest shall be allowed on any money judgment in a civil case recovered in a district court." It is well-settled that the court may award interest from the date of the verdict where an appropriate time has elapsed between the reading of the verdict and entry of the judgment. See Buck v. Burton, 768 F.2d 285, 286-87 (8th Cir. 1985). The delay between the verdict and the judgment was not the plaintiff's fault. We find that the trial court should enter judgment on the verdict and award postjudgment interest from the date of the verdict. The judgment on the verdict and the award of attorney's fees are hereby affirmed. The cause is remanded to the district court with directions to dismiss the prayer for injunctive relief as moot.

LAY, Chief Judge.

ON REHEARING

The petition for rehearing en banc is denied. The plaintiffs' attorney is awarded attorney fees for time expended in this court in the amount of $6,768.75 plus six percent sales tax on said fee. Counsel is likewise awarded reimbursement for expenses in the sum of $1,235.66. Said sum includes the expense of $325.00 for paralegal services.